An ultraviolet photoelectron spectrometer and method of analysis

Abstract

The application discloses an ultraviolet photoelectron spectrum analyzer and an analysis method, and belongs to the technical field of ultraviolet photoelectron spectrum testing, and comprises a monochromatic light generating system, an analysis chamber, a main light path ultraviolet detector, a reference light path ultraviolet detector, a channel electron multiplier, a hemispherical energy analyzer and a two-dimensional electron imaging detector; wherein the main light path ultraviolet detector can detect the photon number of the main light path, and the channel electron multiplier can detect the photoelectron number of the main light path, so as to realize ultraviolet photoelectron yield spectrum testing; the hemispherical energy analyzer comprises a multistage incident lens and a hemispherical deflector, the multistage incident lens is of a variable-diameter structure and the inlet thereof can be opened and closed, and the hemispherical energy analyzer and the two-dimensional electron imaging detector can detect photoelectron energy and quantity information, so as to realize ultraviolet photoelectron energy spectrum testing; the application realizes in-situ combined analysis of ultraviolet photoelectron yield spectrum and energy spectrum, can be cross-verified, and has important significance for exploring the ultraviolet photoelectron emission mechanism of materials.

Description

Technical Field

[0001] This application relates to the field of ultraviolet photoelectron spectroscopy testing technology, and more specifically, to an ultraviolet photoelectron spectroscopy analyzer and analysis method. Background Technology

[0002] With the completion of a series of space infrastructure projects in my country, represented by the BeiDou Navigation Satellite System and the Tiangong Space Station, and the continuous advancement of domestic substitution technologies for semiconductor devices, improving the on-orbit safety and reliability of spacecraft and enhancing my country's domestic research and development capabilities for high-performance semiconductor devices have become critical issues that urgently need to be addressed. In spacecraft charged simulation and semiconductor device bandgap engineering design, the need for accurate testing of material photoelectron emission yield and fine characterization of the electronic band structure on material surfaces places extremely high demands on surface analysis instruments.

[0003] To improve the on-orbit safety of spacecraft and regulate the properties of spacecraft surface materials, it is urgent to study the ultraviolet photoelectron emission mechanism of exposed spacecraft materials. Under the premise of meeting functional performance requirements, materials with high photoelectron emission coefficients should be developed and selected to reduce the risk of surface discharge. By testing the photoelectron emission coefficients of typical exposed spacecraft materials such as thermal control coatings, thermal insulation materials, and thermally conductive fillers, the ionization potential and work function of the materials can be obtained, which helps to understand the charge accumulation and release process of spacecraft in the space environment. Simultaneously, spacecraft surface charging is a process in which the incident charged particle flow on its surface reaches current equilibrium with secondary electrons and photoelectrons. The photoelectron emission coefficient is a necessary parameter in the simulation analysis of spacecraft surface charging potential, and its accuracy is crucial for effectively assessing the surface charging potential and discharge risk of spacecraft.

[0004] Ultraviolet photoelectron spectroscopy (UPS) uses an ultraviolet light source as the excitation source to directly excite outer valence electrons, obtaining the valence band spectrum of the material. It can obtain surface physical information about the intrinsic and eigenstates of the material, and is an important testing method for studying physical parameters such as HOMO levels, work function, and ionization potential. Photoelectron yield spectroscopy (PYS) uses a vacuum ultraviolet monochromator to continuously adjust the incident energy of ultraviolet light, exciting electrons near the band gap and valence band top. By collecting photoelectrons of different energies using an electron multiplier, it can obtain the fine electronic structure of the material's surface states. It is a highly sensitive surface analysis method for testing physical parameters such as vacuum ultraviolet photoemission coefficient and ionization potential.

[0005] Both UPS and PYS are important characterization methods based on the photoelectric effect, but they differ in their detection principles, signal sources, and information depth. Using only one of these techniques often fails to obtain a complete and accurate image of the electronic structure. Summary of the Invention

[0006] This application aims to provide an ultraviolet photoelectron spectroscopy analyzer and analysis method, which is intended to solve the problem that the single UPS analysis or PYS analysis in the existing testing equipment cannot fully and accurately reflect the electronic structure.

[0007] An ultraviolet photoelectron spectroscopy analyzer includes: The analysis chamber is equipped with a four-dimensional sample handling table for placing the sample to be tested. A monochromatic light generating system is sealed to the analysis chamber. The monochromatic light generating system is equipped with a beam splitter, which is used to split the incident light into reflected light and transmitted light. The transmitted light propagates along the main optical path into the analysis chamber and illuminates the surface of the sample to be tested, while the reflected light propagates along the reference optical path. A main optical path ultraviolet detector is installed in the analysis chamber to detect the number of photons in the main optical path; A reference optical path ultraviolet detector is disposed on the reference optical path for detecting the number of photons in the reference optical path; A channel electron multiplier, located in the analysis chamber, is used to detect the number of photoelectrons in the main optical path; A hemispherical energy analyzer, sealed to the analysis chamber, includes a multi-stage incident lens and a hemispherical deflector. The multi-stage incident lens is positioned at the incident end of the hemispherical deflector and faces the four-dimensional sample stage, used to focus incident photoelectrons. The entrance of the multi-stage incident lens is openable and closable. The multi-stage incident lens includes multiple cylindrical electron lenses, which are connected in series along the axial direction. The multi-stage incident lens has a variable diameter structure. The hemispherical deflector is used to filter photoelectrons with different kinetic energies. A two-dimensional electron imaging detector is connected to the output end of the hemispherical deflector to detect the momentum and energy information of the emitted photoelectrons.

[0008] Optionally, the ultraviolet photoelectron spectroscopy analyzer includes a first test mode and a second test mode. The first test mode is an ultraviolet photoelectron yield spectroscopy test mode, and the second test mode is an ultraviolet photoelectron energy spectroscopy test mode. In the first test mode, only the channel electron multiplier is working, and the entrance of the multi-stage incident lens is closed. In the second test mode, only the hemispherical energy analyzer and the two-dimensional electron imaging detector are working, and the entrance of the multi-stage incident lens is open.

[0009] Optionally, the hemispherical energy analyzer is located at the upper end of the analysis chamber, and the multi-stage incident lens is arranged vertically directly above the four-dimensional sample operating stage; the multi-stage incident lens is provided with a fully automatic aperture at one end near the four-dimensional sample operating stage, and the fully automatic aperture is used to control the entrance of the multi-stage incident lens to be closed in the first test mode or opened in the second test mode.

[0010] Optionally, the multi-stage incident lens is a five-element incident lens, which includes a variable diameter region located at both ends of the five-element incident lens; in the variable diameter region, the radius of the electronic lens gradually decreases from the middle to the end of the five-element incident lens.

[0011] Optionally, in the axial direction of the multi-stage incident lenses, the axial length of the electronic lens located in the middle region is greater than the axial length of the electronic lens located in the end region.

[0012] Optionally, the two-dimensional electron imaging detector includes a microchannel plate assembly, a fluorescent screen, and an industrial camera; the microchannel plate assembly includes a first microchannel plate and a second microchannel plate stacked sequentially, with the electron emission surface of the first microchannel plate opposite to the electron incident surface of the second microchannel plate; the microchannel plate assembly is used to amplify photoelectrons; the fluorescent screen is disposed on one side of the electron emission surface of the second microchannel plate, and is used to receive electron impacts and generate fluorescence images; the industrial camera is disposed close to the side of the fluorescent screen away from the second microchannel plate, and is used to acquire images on the fluorescent screen.

[0013] Optionally, the channel axes of the first microchannel plate and the second microchannel plate are at an angle of 5° to 15° to the normal direction of the microchannel plate assembly, respectively.

[0014] Optionally, the focusing electrode of the channel electron multiplier is oriented toward the four-dimensional sample stage and forms a 30° angle with the horizontal plane.

[0015] Optionally, the ultraviolet detector of the reference optical path includes a photodiode and a photomultiplier tube. The photodiode is used to detect photons in the reference optical path under a first light intensity condition, and the photomultiplier tube is used to detect photons in the reference optical path under a second light intensity condition.

[0016] Optionally, the first light intensity condition is that the number of photons at an incident wavelength of 160 nm is ≤7×10⁻⁶. 8 The second light intensity condition is that at an incident wavelength of 160 nm, the number of photons is >7 × 10⁻⁶. 8 .

[0017] Optionally, the photodiode is movably disposed between the beam splitter and the photomultiplier tube. The photodiode is connected to a driving mechanism, which drives the photodiode to rotate or move so that the position of the photodiode is on or off the reference optical path.

[0018] Optionally, the monochromatic light generating system includes an ultraviolet light source, which includes a deuterium lamp and / or a xenon lamp.

[0019] Optionally, the four-dimensional sample operating stage includes a four-dimensional adjustment bracket, a sample stage, and a sample stage temperature control system. The sample stage is mounted on the four-dimensional adjustment bracket, which is used to adjust the position and angle of the sample stage within the analysis chamber. The four-dimensional adjustment bracket includes a linear adjustment structure that moves along the X-axis, Y-axis, and Z-axis, and a rotary adjustment structure that rotates around the R-axis. The sample stage temperature control system is connected to the sample stage and is used to regulate the temperature of the sample stage, with a temperature regulation range of -160℃ to 120℃.

[0020] This application also proposes an in-situ coupled ultraviolet photoelectron yield spectroscopy and energy dispersive spectroscopy analysis method, applied in the ultraviolet photoelectron spectrometer described above, the method comprising the following steps: Under the same vacuum environment and without moving the spatial position of the sample under test, the first test mode and the second test mode are executed respectively. The first test mode is the ultraviolet photoelectron yield spectrum test mode: a monochromatic ultraviolet light with a continuously tunable wavelength is generated by a monochromatic light generation system and irradiated onto the surface of the sample to be tested; the intensity of the incident light is monitored by an ultraviolet detector in the reference optical path; the entrance of the multi-stage incident lens is closed; and the number of photoelectrons emitted by the sample at different wavelengths is detected by a channel electron multiplier to generate an ultraviolet photoelectron yield spectrum. The second test mode is the ultraviolet photoelectron spectroscopy test mode: monochromatic ultraviolet light of a fixed wavelength is generated by the monochromatic light generation system and irradiated onto the surface of the sample to be tested; the entrance of the multi-stage incident lens is opened; the energy and momentum distribution of the emitted photoelectrons are detected by the hemispherical energy analyzer and the two-dimensional electron imaging detector to generate an ultraviolet photoelectron spectrum; Based on the test results of the first test mode and the second test mode, the electronic structure physical parameters of the sample under test are cross-validated.

[0021] Optionally, the method includes: The photoelectron yield of the sample under test is measured at multiple different wavelengths to obtain the photoelectron yield spectrum of the sample under test. The multiple different wavelengths belong to the vacuum ultraviolet band. The horizontal axis of the photoelectron yield spectrum is the photon energy corresponding to the wavelength point, and the vertical axis is the photoelectron yield. At the target wavelength point, the momentum and energy information of the photoelectrons emitted by the sample under test are measured to obtain the ultraviolet photoelectron spectrum of the sample under test. The target wavelength point belongs to the vacuum ultraviolet band. The horizontal axis of the ultraviolet photoelectron spectrum is the binding energy, and the vertical axis is the photoelectron intensity. The ionization potential of the sample to be tested is determined based on the photoelectron yield spectrum, and the work function of the sample to be tested is determined based on the ultraviolet photoelectron energy spectrum. Subtracting the ionization potential from the work function yields the valence band top HOMO level of the sample under test.

[0022] Optionally, the photoelectron yield emitted by the sample under test is measured at multiple different wavelengths to obtain the photoelectron yield spectrum of the sample under test, including: The monochromatic light in the vacuum ultraviolet band is split into a main transmission path and a reference reflection path at multiple different wavelengths. The number of incident photons in the reference optical path at each wavelength point is measured, and the number of incident photons in the main optical path at each wavelength point is also measured. The splitting ratio at each wavelength point is calculated based on the number of incident photons in the main optical path and the number of incident photons in the reference optical path at each wavelength point. The number of photoelectrons excited by the main optical path on the surface of the sample under test at each wavelength point is measured. The photoelectron yield spectrum of the sample under test is determined based on the splitting ratio at each wavelength point, the number of incident photons in the reference optical path, and the number of photoelectrons.

[0023] Optionally, the photoelectron yield spectrum of the sample under test is determined based on the splitting ratio at each wavelength, the number of incident photons in the reference optical path, and the number of photoelectrons, including: Based on the splitting ratio at each wavelength point, the number of incident photons in the main optical path at the corresponding wavelength point is corrected to obtain the actual number of incident photons in the main optical path at each wavelength point. Divide the number of photoelectrons at each wavelength point by the actual number of incident photons at the corresponding wavelength point to obtain the photoelectron yield value at each wavelength point. The photoelectron yield spectrum of the sample under test is obtained based on the photoelectron yield values ​​at the multiple different wavelength points.

[0024] Optionally, determining the ionization potential of the sample to be tested based on the photoelectron yield spectrum includes: Based on the material type of the sample to be tested, select the corresponding power function model; Based on the power function model, a polynomial fitting calculation is performed on the starting region of the rising edge of the photoelectron yield spectrum to obtain the fitting curve. The ionization potential of the sample to be tested is determined based on the photoelectron yield spectrum and the fitted curve.

[0025] Optionally, the ionization potential of the sample to be tested is determined based on the photoelectron yield spectrum and the fitted curve, including: From the ultraviolet photoelectron yield spectrum, a horizontal baseline with a photoelectron yield value of zero is determined through data processing; Based on a preset power function model related to the material type of the sample to be tested, the rising edge starting region of the ultraviolet photoelectron yield spectrum is fitted to obtain a fitting curve. The fitted curve is extended towards the direction of low photon energy, and its intersection with the horizontal baseline is calculated. The photon energy value corresponding to the intersection is determined as the ionization potential of the sample to be tested.

[0026] Optionally, based on the material type of the sample to be tested, a corresponding power function model is selected, including: Based on the material type of the sample to be tested, determine the excitation type and scattering type of the sample to be tested; Based on the excitation type and scattering type of the sample to be tested, a corresponding exponent value is defined for the power function model; Based on the power function model, a polynomial fitting calculation is performed on the starting region of the rising edge of the photoelectron yield spectrum to obtain the fitting curve, including: A nonlinear least squares fitting algorithm is used to fit the photon energy and photoelectron emission yield of the data points in the starting region to a polynomial function based on the exponent value defined by the power function model, thereby obtaining the fitting curve.

[0027] Optionally, at the target wavelength, the photoelectron momentum and energy information emitted by the sample under test are measured to obtain the ultraviolet photoelectron spectrum of the sample under test, including: The sample to be tested is irradiated with a photon beam of the target wavelength to obtain photoelectrons with different kinetic energies excited by the sample to be tested. Using a hemispherical energy analyzer, photoelectrons with different kinetic energies are screened from the photoelectrons with different kinetic energies excited by the sample under test. The signals of photoelectrons with different kinetic energies are amplified by a microchannel plate, and the corresponding light emission images are obtained on a fluorescent screen. The light emission images include pixels at multiple different positions. The luminescent images are captured in segments according to the photoelectron kinetic energy using an industrial camera. All the light-emitting images captured by the industrial camera are superimposed, and the pixels with the same electron kinetic energy are integrated to obtain the ultraviolet photoelectron spectrum of the sample under test.

[0028] Optionally, the work function of the sample to be tested is determined based on the ultraviolet photoelectron spectrum, including: The energy value of the secondary electron cutoff edge was determined from the ultraviolet photoelectron spectrum. The work function of the sample under test is calculated based on the photon energy corresponding to the target wavelength point and the secondary electron cutoff edge energy value.

[0029] Optionally, the secondary electron cutoff edge energy value is determined from the ultraviolet photoelectron spectrum, including: A digital filtering algorithm is used to process the ultraviolet photoelectron spectrum to obtain the noise-reduced ultraviolet photoelectron spectrum and the noise intensity level line. From the denoised ultraviolet photoelectron spectrum, a linear variation region containing the secondary electron cutoff edge was determined; The least squares method is used to linearly fit the relationship between photon intensity and photoelectron kinetic energy in the linearly changing region, and a fitted straight line is obtained. The intersection point of the fitted straight line and the noise intensity horizontal line is determined, and the photoelectron kinetic energy corresponding to the intersection point is determined as the secondary electron cutoff edge energy value.

[0030] Optionally, from the denoised ultraviolet photoelectron spectrum, a linear variation region containing the secondary electron cutoff edge is determined, including: Calculate the first derivative of the denoised ultraviolet photoelectron spectrum to obtain the derivative curve; From the derivative curve, the point on the horizontal axis corresponding to the photoelectron kinetic energy where the absolute value of the derivative first exceeds a preset threshold is determined as the starting point; Using the starting point as a reference, a predetermined energy width range is extended to the side with low photoelectron kinetic energy to obtain the linear variation region.

[0031] Beneficial effects: The ultraviolet photoelectron spectroscopy analyzer described in this application integrates the functions of UPS analysis and PYS analysis by organically combining components such as a monochromatic light generation system, an analysis chamber, a main optical path ultraviolet detector, a reference optical path ultraviolet detector, a channel electron multiplier, and a hemispherical energy analyzer. The main optical path ultraviolet detector and the channel electron multiplier are used to detect the number of photons and photoelectrons in the main optical path, respectively, to achieve ultraviolet photoelectron yield spectrum testing; the hemispherical energy analyzer can detect the energy and quantity information of photoelectrons, achieving ultraviolet photoelectron energy spectrum testing. The entrances of the multi-stage incident lenses in the hemispherical energy analyzer can be opened and closed. During PYS analysis, closing the entrances of the multi-stage incident lenses can provide electric field isolation, thereby reducing signal crosstalk. Furthermore, the setting of the reference optical path ultraviolet detector can be used to monitor the stability of the incident light, further improving the accuracy of the test. The ultraviolet photoelectron spectroscopy analyzer described in this application has a compact structure and comprehensive functions. It can achieve high-precision coexistence of two detection modes in the same device, realize joint analysis and cross-validation of ultraviolet yield spectrum and energy spectrum, which is beneficial for obtaining fine characterization of the electronic structure of the valence band on the material surface (especially in the low density state region), and can obtain electronic structure characterization of the interstitial states of the material. It improves testing efficiency, reduces testing error, and is of great significance for exploring the ultraviolet photoelectron emission mechanism of materials.

[0032] The analytical method described in this application has the same advantages as the aforementioned ultraviolet photoelectron spectroscopy analyzer compared to the prior art, and will not be repeated here. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of an ultraviolet photoelectron spectroscopy analyzer proposed in one embodiment of this application; Figure 2 This is a schematic diagram of the structure of a five-element incident lens in an ultraviolet photoelectron spectroscopy analyzer proposed in one embodiment of this application; Figure 3 This is a schematic diagram of the arrangement of channel electron multipliers in an ultraviolet photoelectron spectroscopy analyzer according to an embodiment of this application; Figure 4 This is a schematic diagram of the arrangement of photodiodes and photomultiplier tubes in an ultraviolet photoelectron spectroscopy analyzer according to an embodiment of this application; Figure 5 A schematic diagram of the steps of the in-situ coupled ultraviolet photoelectron spectroscopy and energy dispersive spectroscopy analysis method proposed in an embodiment of this application; Figure 6 This is a graph showing the ultraviolet photoelectron spectroscopy test results of a gold sample according to an embodiment of this application; Figure 7 This is a graph showing the ultraviolet photoelectron spectroscopy test results of a gold sample proposed in an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures: A. Monochromatic light generation system; B. Analysis chamber; C. Sample introduction chamber; 1-1. Deuterium lamp; 1-2. Xenon lamp; 2. Ring mirror; 3. Filter; 4. Vacuum ultraviolet monochromator; 5. Collimating mirror; 6. Reference optical path ultraviolet detector; 61. Photomultiplier tube; 62. Photodiode; 7. Beam splitter; 8. Electronic shutter; 9. Focusing mirror; 10. Four-dimensional sample handling stage; 11. Main optical path ultraviolet detector; 12. Neutralizing electron gun; 13. Channel electron multiplier; 131. Metal grid; 14. Magnetic sample transfer rod; 15. Argon ion gun; 16. Helium lamp; 17. Five-element incident lens; 171. First lens; 172. Second lens; 173. Third lens; 174. Fourth lens; 175. Fifth lens; 18. Hemispherical deflector; 19. Two-dimensional electron imaging detector. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Among related technologies, ultraviolet photoelectron spectroscopy (UPS) uses an ultraviolet light source as the excitation source to directly excite outer valence electrons to obtain the valence band spectrum of the material. It can obtain surface physical information of intrinsic and extrinsic states of the material and is an important testing method for studying physical parameters such as HOMO levels, work function, and ionization potential. Photoelectron yield spectroscopy (PYS) uses a vacuum ultraviolet monochromator to continuously adjust the incident energy of ultraviolet light, exciting electrons near the band gap and valence band top. By collecting photoelectrons of different energies using an electron multiplier, it can obtain the fine electronic structure of the material's surface states. It is a highly sensitive surface analysis method for testing physical parameters such as vacuum ultraviolet photoelectron emission coefficient and ionization potential.

[0038] Standalone UPS or PYS analysis is often insufficient to fully describe the electronic structure of interfaces or materials. In practical analysis, UPS and PYS are typically cross-referenced for data cross-validation. However, UPS and PYS are usually performed by different dedicated devices, requiring sample transfer between them. The inability to maintain the same spatial location and surface condition between measurements leads to distortion in the quantitative correspondence between yield and energy spectra, which cannot be fully corrected through post-processing, increasing testing complexity and error. While some attempts have tried to integrate both functions into a single device, most simply combine two independent modules into the same cavity, resulting in issues such as physical field compatibility, spatial layout, and signal crosstalk.

[0039] In view of this, embodiments of this application propose an ultraviolet photoelectron spectroscopy analyzer.

[0040] See Figure 1 An ultraviolet photoelectron spectroscopy analyzer includes a monochromatic light generation system A, an analysis chamber B, a main optical path ultraviolet detector 11, a reference optical path ultraviolet detector 6, a channel electron multiplier 13, and a hemispherical energy analyzer. The analysis chamber B is equipped with a four-dimensional sample operation stage 10 for placing the sample to be tested; the monochromatic light generation system A is sealed to the analysis chamber B, and the monochromatic light generation system A is equipped with a beam splitter 7, which is used to split the incident light into reflected light and transmitted light. The transmitted light propagates along the main light path into the analysis chamber B and irradiates the surface of the sample to be tested, while the reflected light propagates along the reference light path. The main optical path ultraviolet detector 11 is installed in the analysis chamber B and is used to detect the number of photons in the main optical path; the reference optical path ultraviolet detector 6 is installed in the reference optical path and is used to detect the number of photons in the reference optical path; the channel electron multiplier 13 is installed in the analysis chamber B and is used to detect the number of photoelectrons in the main optical path. The hemispherical energy analyzer is sealed to the analysis chamber B and includes a multi-stage incident lens and a hemispherical deflector 18. The multi-stage incident lens is disposed at the incident end of the hemispherical deflector 18 and faces the four-dimensional sample operation stage 10, and is used to focus the incident photoelectrons. The entrance of the multi-stage incident lens is openable and closable. The multi-stage incident lens includes multiple cylindrical electron lenses, which are connected in series along the axial direction. The multi-stage incident lens has a variable diameter structure. The hemispherical deflector 18 is used to filter photoelectrons with different kinetic energies. A two-dimensional electron imaging detector 19 is connected to the output end of the hemispherical deflector 18 and is used to detect the momentum and energy information of the emitted photoelectrons.

[0041] Specifically, analysis chamber B is a vacuum chamber used to provide the vacuum environment required for detection, preventing charged particles in the atmosphere from interfering with experimental results. Its inner walls are coated with a material with a low secondary electron emission coefficient (such as colloidal graphite), and multiple grounding loops are constructed to eliminate secondary electron interference caused by stray light. Monochromatic light generation system A is sealed to analysis chamber B. It includes a UV light source, a pre-optical system, a vacuum UV monochromator 4, and a post-optical system arranged sequentially. The UV light generated by the UV light source is converted into monochromatic light after passing through the pre-optical system and the vacuum UV monochromator 4, and then enters the post-optical system. The beam splitter 7 in the post-optical system, also called a beam splitter, splits the monochromatic light into two paths: reflected light and transmitted light. The transmitted light propagates along the main optical path into analysis chamber B and illuminates the surface of the sample to be tested, triggering a photoelectron emission process. The reflected light propagates along the reference optical path.

[0042] The analysis chamber B is equipped with a main optical path ultraviolet detector 11 and a channel electron multiplier 13, which are used to detect the number of photons and photoelectrons in the main optical path, respectively, thereby enabling ultraviolet photoelectron yield spectrum testing.

[0043] The hemispherical energy analyzer is sealed and connected to the top of the analysis chamber B. It includes a multi-stage incident lens and a hemispherical deflector 18. The photoelectrons emitted from the surface of the sample under test are focused by the multi-stage incident lens and enter the hemispherical deflector 18. They are accelerated and deflected in the hemispherical deflector 18 and finally the momentum and energy information are detected by the two-dimensional electron imaging detector 19. Thus, ultraviolet photoelectron spectroscopy can be achieved.

[0044] The entrance to the multi-stage incident lens is openable and closable, switching between open and closed states depending on the test mode. Specifically, the ultraviolet photoelectron spectroscopy analyzer includes a first test mode (i.e., ultraviolet photoelectron yield spectroscopy test mode) and a second test mode (i.e., ultraviolet photoelectron energy spectroscopy test mode). In the second test mode, i.e., during UPS analysis, only the hemispherical energy analyzer and the two-dimensional electron imaging detector 19 are operational. At this time, the entrance to the multi-stage incident lens is open, allowing photoelectrons to enter the multi-stage incident lens normally for energy spectroscopy testing. In the first test mode, i.e., during PYS analysis, only the channel electron multiplier 13 is operational. At this time, the entrance to the multi-stage incident lens is closed, isolating the participating electric field generated by the multi-stage incident lens, thereby avoiding signal interference and improving the accuracy of PYS testing.

[0045] A reference optical path ultraviolet detector 6 is also provided in the reference optical path, which can receive the illumination of reflected light and detect the number of photons in the reference optical path, and can be used to monitor the stability of the incident light. In related technologies, the UPS module and PYS module are simply assembled in the same vacuum chamber. High-intensity ultraviolet light irradiation will generate a large number of scattered electrons and secondary electrons, which will interfere with the detection of weak photoelectron signals and have optical and electronic compatibility problems. However, in the embodiment of this application, with the setting of the reference optical path and the main optical path, the detection of weak photons in the main optical path can be determined by the splitting ratio, thereby effectively overcoming the above-mentioned physical field compatibility problem.

[0046] With the above settings, the ultraviolet photoelectron spectroscopy analyzer provided in this embodiment can achieve high-precision compatibility between two detection modes in the same device, realize in-situ combined analysis and cross-validation of ultraviolet photoelectron emission spectra and energy spectra, and, based on the PYS test results, determine the ultraviolet photoelectron emission yield. Y Functional relationship between IP and ionization potential ( Y ~( hv -IP) n , hv The ionization potential IP of the sample under test can be determined by the incident photon energy, and the Fermi level of the sample under test can be determined based on the UPS test results. E F Work function W, valence band top HOMO level E HOMO With equal physical parameters, the electronic energy level structure relationship allows for joint analysis and cross-validation of the two methods. The electronic energy level structure relationship is as follows: .

[0047] The ultraviolet photoelectron spectroscopy analyzer provided in this embodiment avoids spatial position deviations and surface state changes caused by sample transfer between different devices. It effectively solves the problem of distortion in the quantitative correspondence between yield spectrum and energy spectrum when traditional separate tests are performed, thus reducing test errors. Furthermore, the integration of the two testing functions eliminates the need for frequent changes in testing equipment and samples, simplifying the testing process and improving efficiency. Moreover, through dual-path photoelectric detection of the main optical path and reference optical path, an in-situ calibration mechanism for the main light source intensity and a traceable calibration system for the spectrophotometer ratio are established, ensuring the stability of the light source intensity and the accuracy of the measurement.

[0048] Specifically, the main optical path ultraviolet detector 11 can be a standard photodiode with calibrated spectral responsivity, which can be used to calibrate the photon count and splitting ratio of the main optical path before measurement. The standard photodiode is connected to a galvanometer, and the photon count of the main optical path can be calculated from the photocurrent of the main optical path. The channel electron multiplier 13 can effectively collect photoelectrons emitted from the material surface, multiply the emitted photoelectrons, and convert them into electrical signals for measurement. The channel electron multiplier 13 is connected to a photoelectron counter, which counts the number of photoelectrons based on the electrical signal output by the channel electron multiplier 13.

[0049] Optionally, the hemispherical energy analyzer is located at the upper end of the analysis chamber B, and the multi-stage incident lens is arranged vertically directly above the four-dimensional sample operation stage 10; the multi-stage incident lens is provided with a fully automatic aperture at one end near the four-dimensional sample operation stage 10, and the fully automatic aperture is used to control the entrance of the multi-stage incident lens to be closed in the first test mode or opened in the second test mode.

[0050] Specifically, after the sample is irradiated with ultraviolet light, its surface material releases photoelectrons due to the photoelectric effect. The multi-stage incident lens is arranged vertically above the four-dimensional sample operation stage 10, so that the released photoelectrons can be collected and focused by the multi-stage incident lens above, thereby reducing the electron beam divergence angle as much as possible and increasing the electron flux entering the hemispherical energy analyzer.

[0051] The fully automatic aperture is positioned near the entrance of the multi-stage incident lens, close to the four-dimensional sample stage 10. Driven by a high-precision motor, the aperture automatically controls the opening and closing of the entrance to the multi-stage incident lens according to the test mode. During ultraviolet photoelectron yield spectroscopy (PYS) testing, the aperture closes the entrance, physically blocking it and isolating any residual electrostatic field that may be generated when the lens is in operation. This prevents the lens electric field from disturbing the trajectory of low-energy photoelectrons, ensuring that the channel electron multiplier 13 can collect photoelectrons emitted from the surface of the sample without interference, thus improving the accuracy of PYS testing. During ultraviolet photoelectron energy dispersive spectroscopy (UPS) testing, the aperture opens the entrance, allowing photoelectrons to enter the lens normally and, after focusing, enter the hemispherical deflector 18 for energy analysis. With the fully automatic aperture setting, the opening and closing status of the multi-stage incident lens inlet can be automatically controlled according to the different test modes, ensuring the normal and smooth operation of the two test modes and avoiding signal interference.

[0052] Furthermore, the multi-stage incident lens includes multiple electronic lenses connected in series. Specifically, the electronic lens is a conductor electrode with a rotationally symmetric geometry. In this embodiment, multiple cylindrical electronic lenses made of non-magnetic aluminum alloy are used. The multiple electronic lenses are connected in series along the axial direction. By applying different voltages, the focusing and acceleration state of the electron beam in the incident direction can be controlled, so that the electrons enter the dispersion region of the hemispherical energy analyzer along a predetermined trajectory, ensuring an optimized balance between energy resolution and transmittance.

[0053] Multi-stage incident lenses can adjust the electric field in segments to create a specific electric field distribution, thereby focusing the electron beam. Employing a variable-diameter structure, multi-stage incident lenses can generate more complex electric field distributions. Compared to constant-diameter lenses, they allow for more flexible adjustment of the electric field gradient, facilitating better control of the electron path. Furthermore, the variable-diameter structure allows for different focusing intensities at different locations, thus optimizing electron focusing over longer paths and reducing aberrations. In addition, given the limited space in practical instruments, the variable-diameter structure can achieve the desired electric field distribution within a shorter length, helping to reduce space requirements and make the overall structure more compact.

[0054] The hemispherical deflector 18 includes two concentric hemispherical electrostatic electrodes, namely an inner spherical electrode and an outer spherical electrode. By adjusting the electrostatic potential difference between the two electrodes, the conditions for passing through electrons with specific kinetic energies can be set, thereby achieving selective energy analysis of electrons. Specifically, in the hemispherical deflector 18, electrons with different kinetic energies are deflected along different trajectories under the action of an electric field. Only when the kinetic energy of the electron matches the set center energy can the electron pass through the hemisphere along an equipotential trajectory and reach the exit slit. Electrons deviating from the set energy will be deflected to a non-channel region and blocked, thus achieving energy separation of electrons.

[0055] The two-dimensional electron imaging detector 19 is located at the output end of the hemispherical energy analyzer 18. It is used to receive the energy-sorted electronic signal, amplify the electronic signal, and convert it into a visible light image.

[0056] By setting up multiple levels of incident lenses, the focusing ability of incident photoelectrons is improved, the energy resolution and electron collection efficiency of the hemispherical energy analyzer are enhanced, aberrations and chromatic aberrations are effectively suppressed, and it can still maintain high resolution performance in the low-energy electron region, which helps to improve the repeatability and quantitative reliability of energy spectrum test results.

[0057] Optionally, the multi-stage incident lens is a five-element incident lens 17, which includes five electronic lenses connected in series. The five-element incident lens 17 includes a variable diameter region located at both ends of the five-element incident lens 17. In the variable diameter region, the radius of the electronic lens gradually decreases from the middle to the end of the five-element incident lens 17.

[0058] Specifically, in this embodiment, the multi-stage incident lens is a five-element incident lens 17. Compared with a conventional binary lens, the five-element incident lens 17 has a wider energy adjustment range, can simultaneously meet the focusing requirements under multiple energies, and can significantly reduce the effects of spherical aberration and chromatic aberration, achieving high-performance focusing. Figure 2 As shown, the five-element incident lens 17 includes a first lens 171, a second lens 172, a third lens 173, a fourth lens 174, and a fifth lens 175 connected in series. In specific applications, the first lens 171 is positioned towards the four-dimensional sample operating stage 10, and the fifth lens 175 is positioned towards the hemispherical deflector 18. The potential of the first lens 171 is generally the same as the potential of the sample to be measured, and the potential of the fifth lens 175 is generally the same as the potential of the base of the hemispherical deflector 18. The variable diameter region of the five-element incident lens 17 is located at both ends of the five-element incident lens 17. Specifically, the variable diameter region is located at the first lens 171 and the fifth lens 175. The radius of the first lens 171 gradually decreases from the end closer to the second lens 172 towards the end closer to the four-dimensional sample operating stage 10, and the radius of the fifth lens 175 gradually decreases from the end closer to the fourth lens 174 towards the end closer to the hemispherical deflector 18.

[0059] The variable diameter design of the first lens 171 helps to better match the emission characteristics of the sample under test, reduce energy loss, and improve detection sensitivity. The variable diameter design of the fifth lens 175 helps to better mate with the hemispherical deflector 18, ensuring that the electron beam can enter the deflection system accurately and stably, achieving high-precision energy analysis and angle resolution.

[0060] Optionally, in the axial direction of the multi-stage incident lenses, the axial length of the electronic lens located in the middle region is greater than the axial length of the electronic lens located in the end region.

[0061] For the five-element incident lens 17, the axial lengths of the first lens 171, the second lens 172, and the third lens 173 gradually increase, while the axial lengths of the third lens 173, the fourth lens 174, and the fifth lens 175 gradually decrease. Specifically, in this embodiment, the axial length of the first lens 171 is 40 mm, the axial length of the second lens 172 is 160 mm, the axial length of the third lens 173 is 213 mm, the axial length of the fourth lens 174 is 173 mm, and the axial length of the fifth lens 175 is 113 mm. Among them, the third lens 173, as the intermediate lens, is the main focusing area and has the longest axial length, which helps to optimize the electric field transition, reduce spherical aberration, and better focus and guide the electron beam. The first lens 171 and the fifth lens 175, as end lenses, have shorter axial lengths that help suppress edge effects and avoid coupling interference with other components such as the hemispherical deflector 18 and the two-dimensional electron imaging detector 19.

[0062] Optionally, the two-dimensional electron imaging detector 19 includes a microchannel plate assembly, a fluorescent screen, and an industrial camera; the microchannel plate assembly includes a first microchannel plate and a second microchannel plate stacked sequentially, with the electron emitting surface of the first microchannel plate facing the electron incident surface of the second microchannel plate; the fluorescent screen is disposed on one side of the electron emitting surface of the second microchannel plate, for receiving electron impacts and generating a fluorescence image; the industrial camera is disposed close to the side of the fluorescent screen away from the second microchannel plate, for acquiring images on the fluorescent screen.

[0063] Specifically, the electron beam enters the two-dimensional electron imaging detector 19 after passing through the exit slit of the hemispherical energy analyzer. The microchannel plate assembly includes a first microchannel plate and a second microchannel plate stacked together. The electron exit surface of the first microchannel plate is positioned opposite to the electron incident surface of the second microchannel plate. By using two microchannel plates, secondary electron multiplication can be achieved, thereby improving the electron multiplication efficiency.

[0064] The fluorescent screen is set on one side of the electron emission surface of the second microchannel plate. After being multiplied, the electrons strike the fluorescent screen. The electron beams passing through the exit slit have different kinetic energies, and the electrons strike the fluorescent screen at different positions. The fluorescent screen can convert the electron strike positions into visible light signals, and generate corresponding fluorescent images on the fluorescent screen, realizing high-resolution imaging of electron spatial distribution information.

[0065] The industrial camera uses a CMOS camera, which is a camera that employs a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor. This CMOS camera is a research-grade, low-noise, high-sensitivity model. It is positioned close to the side of the fluorescent screen away from the second microchannel plate, enabling real-time acquisition of fluorescence images on the screen for two-dimensional energy spectrum reconstruction.

[0066] With the above setup, the microchannel plate assembly has extremely high electron multiplication capability, which can amplify extremely weak photoelectron signals to a detectable range. The fluorescent screen converts the electron collision position into a visible light signal, realizing the conversion of electron position into an image. The CMOS camera is used for high-resolution digital imaging. Through the combined effect of the microchannel plate assembly, fluorescent screen, and CMOS camera, the detection sensitivity and image quality are significantly improved, solving the problems of weak signal and poor positioning accuracy in traditional Faraday cup or simple electron multiplier tube structures.

[0067] Optionally, the channel axes of the first microchannel plate and the second microchannel plate are at an angle of 5° to 15° to the normal direction of the microchannel plate assembly, respectively.

[0068] Specifically, the channel axes of the two microchannel plates are at an angle of 5° to 15° to the normal direction of the microchannel plate assembly. The inclined channel axis extends the path length of electrons in the channel, which is conducive to multiple interactions between electrons and the channel walls, thereby increasing the number of secondary electron emissions and improving the multiplication efficiency. The channels of the two microchannel plates are inclined in opposite directions, forming a Chevron-type (V-shaped) staggered structure, which can prevent positive ions generated at the output end from flowing back to the input end, thereby avoiding noise and gain saturation problems caused by ion feedback.

[0069] By optimizing the structure of the microchannel plate assembly, the electron focusing capability and multiplication efficiency were improved. The improved electron focusing capability significantly enhanced the spatial resolution and imaging quality of the two-dimensional electron imaging detector 19, while the improved multiplication efficiency enhanced the detector's response to weak signals and expanded the dynamic range. In particular, it significantly improved the sensitivity in low-energy electron detection, providing strong support for precise analysis in fields such as surface and interface physics, nanomaterials, and advanced semiconductors.

[0070] Optionally, a metal grid 131 is also provided at the incident end of the focusing electrode of the channel electron multiplier 13. The metal grid 131 can isolate the disturbance of the incident lens electric field on the electron trajectory at the entrance of the channel electron multiplier 13 in PYS mode.

[0071] Optionally, the focusing electrode of the channel electron multiplier 13 is oriented toward the four-dimensional sample stage 10 and forms a 30° angle with the horizontal plane.

[0072] Specifically, the channel electron multiplier 13 is mounted on the flange of the analysis chamber B via a bracket. The distance between the channel electron multiplier 13 and the sample can be adjusted linearly. The focusing electrode of the channel electron multiplier 13 faces the four-dimensional sample stage 10 for photoelectron collection. See also Figure 3 In this embodiment, the focusing electrode of the channel electron multiplier 13 is configured in a funnel shape, forming a conical or curved collection structure. Compared with the traditional planar collection structure, this can alleviate the problem of edge electric field divergence and improve the spatial focusing efficiency of photoelectrons. Simultaneously, the channel electron multiplier 13 is tilted, with its axis forming a 30° angle with the horizontal plane. This effectively matches the emission trajectory of photoelectrons, reducing photoelectron deflection and scattering losses, and improving photoelectron capture efficiency.

[0073] Optionally, the reference optical path ultraviolet detector 6 includes a photodiode 62 and a photomultiplier tube 61. The photodiode 62 is used to detect photons in the reference optical path under a first light intensity condition, and the photomultiplier tube 61 is used to detect photons in the reference optical path under a second light intensity condition.

[0074] Specifically, the photon count in the reference optical path is measured in a dual-mode manner. The ultraviolet detector 6 in the reference optical path may include a photodiode 62 and a photomultiplier tube 61. The photomultiplier tube 61 is used for measurement under low light intensity conditions, while the photodiode 62 is used for measurement under high light intensity conditions. Through complementary detection ranges, ultra-large dynamic range, anti-saturation, and high signal-to-noise ratio full-intensity adaptive detection can be achieved.

[0075] Optionally, the photodiode 62 is movably disposed between the beam splitter 7 and the photomultiplier tube 61. The photodiode 62 is connected to a driving mechanism, which drives the photodiode 62 to rotate or move so that the position of the photodiode 62 is on or off the reference optical path.

[0076] For details, see Figure 4 Along the direction of the reference optical path, the photodiode 62 is movably disposed between the beam splitter 7 and the photomultiplier tube 61. The driving mechanism can be a linear driving structure or a rotating structure. By driving the second photodiode 62 to move linearly or rotate, the position of the photodiode 62 can be changed so that it is on or off the reference optical path, thereby realizing the switching of the photon number measurement mode of the reference optical path.

[0077] Specifically, under the first light intensity condition, which is usually when the light intensity is low, the photodiode 62 is driven to rotate or move away from the reference optical path by the driving mechanism. At this time, the reflected light formed by the beam splitter 7 can illuminate the photomultiplier tube 61 along the reference optical path, and the photomultiplier tube 61 performs photon detection of the reference optical path. Under the second light intensity condition, which is usually when the light intensity is high, the photodiode 62 is driven to rotate or move onto the reference optical path by the driving mechanism. At this time, the photodiode 62 blocks the incident end of the photomultiplier tube 61. The reflected light formed by the beam splitter 7 illuminates the photodiode 62 along the reference optical path, and the photodiode 62 performs photon detection of the reference optical path.

[0078] Optionally, the first light intensity condition is that the number of photons at an incident wavelength of 160 nm is ≤7×10⁻⁶. 8 The second light intensity condition is that at an incident wavelength of 160 nm, the number of photons is >7 × 10⁻⁶. 8 .

[0079] Optionally, the ultraviolet light source includes a deuterium lamp 1-1 and / or a xenon lamp 1-2.

[0080] Specifically, the ultraviolet light source can be a high-power, high-stability deuterium lamp 1-1, or a high-power, wide-bandwidth, high-stability xenon lamp 1-2. The low incident energy effectively reduces damage to the sample surface caused by ultraviolet irradiation and avoids charging issues in insulating samples during testing. Preferably, the ultraviolet photoelectron spectroscopy analyzer provided in this embodiment can be equipped with both deuterium lamp 1-1 and xenon lamp 1-2. Since the light intensity of the deuterium lamp 1-1 spectrum is relatively low above 300 nm, it can be replaced by xenon lamp 1-2 for testing.

[0081] Optionally, the vacuum ultraviolet monochromator 4 is a holographic concave grating structure with a wavelength resolution of 0.070 nm @ 254 nm (mercury lamp characteristic spectral lines). The structural design of the vacuum ultraviolet monochromator 4, using either a deuterium lamp 1-1 or a xenon lamp 1-2, enables continuously adjustable output wavelengths from 115 nm to 400 nm. This overcomes the problems of fixed wavelength bands and discrete wavelength adjustment in traditional ultraviolet light sources, allowing for a series of ultraviolet photoelectron spectral tests at different incident energies, eliminating spurious peaks, and improving test accuracy.

[0082] Furthermore, since most UPS testing systems on the market currently use helium lamps as ultraviolet light sources, in order to facilitate comparative testing, a helium lamp 16 is also installed in the analysis chamber B in this embodiment, which can perform ultraviolet photoelectron spectroscopy testing with an incident energy of 21.2 eV.

[0083] Optionally, the front optical system includes a ring mirror 2 and a filter 3 arranged in sequence; the rear optical system also includes a collimating mirror 5 and a focusing mirror 9, with the collimating mirror 5 located at the incident end of the beam splitter 7 and the focusing mirror 9 located at the exit end of the beam splitter 7 along the main optical path.

[0084] Specifically, the annular mirror 2 optimizes light intensity and energy, the filter 3 filters out higher-order diffracted light, the collimating mirror 5 collimates monochromatic light into parallel light, and the focusing mirror 9 is mounted above the four-dimensional sample stage 10 to focus the light spot at the position of the four-dimensional sample stage 10. The cooperation of the front and rear optical systems helps to improve photon energy purity and stability, enhance energy density, and ensure high energy resolution in the test.

[0085] Optionally, when the sample to be tested is placed on the four-dimensional sample operation stage 10, the area of ​​the incident light spot received by the sample to be tested is 2mm×4mm.

[0086] Optionally, an electronic shutter 8 is provided on the main optical path, which is used to control the duration of the transmitted light irradiating the sample.

[0087] Specifically, the electronic shutter 8 can control the time of the ultraviolet monochromatic light incident on the sample to achieve on-demand exposure. Compared with the traditional testing system that uses a conventional ultraviolet light source to continuously irradiate the sample, it can precisely control the exposure time, effectively avoid thermal effects and photo-induced damage to the sample during the testing process, and improve the controllability of the experiment.

[0088] Optionally, the ultraviolet photoelectron spectroscopy analyzer also includes a sample introduction chamber C sealed and connected to the analysis chamber B. The sample introduction chamber C is equipped with a dedicated independent vacuum pump system. Specifically, the sample introduction chamber C can employ a pumping system consisting of a mechanical pump and a molecular pump connected in series. A magnetic sample transfer rod 14 is installed in the sample introduction chamber C. The magnetic sample transfer rod 14 can transfer the sample to be tested to the four-dimensional sample operation stage 10 in the analysis chamber B through linear movement.

[0089] Optionally, the ultraviolet photoelectron spectrometer further includes a neutralizing electron gun 12 and an argon ion gun 15. The neutralizing electron gun 12 is installed in the analysis chamber B and can perform charge neutralization and hemispherical energy calibration on the surface of the sample to be tested; the argon ion gun 15 is installed in the sample introduction chamber C and can be used to clean the surface of the sample to be tested.

[0090] Optionally, the four-dimensional sample operating stage 10 includes a four-dimensional adjustment bracket, a sample stage, and a sample stage temperature control system. The sample stage is mounted on the four-dimensional adjustment bracket, which is used to adjust the position and angle of the sample stage within the analysis chamber B. The four-dimensional adjustment bracket includes a linear adjustment structure that moves along the X-axis, Y-axis, and Z-axis directions, and a rotary adjustment structure that rotates around the R-axis. The sample stage temperature control system is connected to the sample stage and is used to regulate the temperature of the sample stage, with a temperature regulation range of -160℃ to 120℃.

[0091] Specifically, the four-dimensional adjustment bracket is also sealed to the analysis chamber B, ensuring the entire system operates in a high vacuum environment. The X, Y, and Z axes represent the front-back, left-right, and up-down directions in space, respectively, while the R axis represents the radial direction of the four-dimensional adjustment bracket. Furthermore, the horizontal displacement range of the X and Y axes is ±5mm, with a repeatability of no less than 0.05mm; the vertical movement range of the Z axis is 50mm, with a repeatability of no less than 0.05mm; and the rotation angle range of the R axis is ±120°, with a rotation control accuracy better than 1°. The sample stage temperature control system is connected to the sample stage and is used to regulate its temperature, with a temperature control range of -160℃ to 120℃. By setting up the sample stage temperature control system, precise control of the sample temperature can be achieved, ensuring the stability and repeatability of photoelectron emission behavior under different experimental conditions.

[0092] In this embodiment, by setting up a four-dimensional adjustment bracket and a sample stage temperature control system, the position, angle, and temperature of the sample stage in the analysis chamber B can be adjusted, which improves the flexibility of the experiment and provides the possibility for conducting multi-angle electron emission analysis or temperature evolution process research.

[0093] Furthermore, the ultraviolet photoelectron spectroscopy analyzer also includes a control system, which includes a monochromatic light generation system control module, a photon counter control module, a photoelectron counter control module, a PYS test module, a UPS test module, and a data storage module.

[0094] Specifically, the monochromatic light generation system control module is connected to the monochromatic light generation system A and is used to control the monochromatic light generation system A to generate monochromatic light of different wavelengths; the photon counter control module is connected to the photon counter, and the photon counter is connected to the ultraviolet detector 6 of the reference optical path. The photon counter control module is used to control the photon counter to count the photons of the reference optical path within a fixed time period; the photoelectron counter control module is connected to the photoelectron counter, and the photoelectron counter is connected to the channel electron multiplier 13. The photoelectron counter control module is used to control the photoelectron counter to count the photoelectrons emitted from the sample surface within a fixed time period.

[0095] The UPS test module is connected to the hemispherical energy analyzer and can generate the ultraviolet photoelectron spectrum of the sample under test based on the photoelectron energy and momentum distribution information of the sample under test at a fixed incident energy.

[0096] The PYS testing module is connected to the main optical path ultraviolet detector 11, the reference optical path ultraviolet detector 6, and the channel electron multiplier 13. It can calculate the photoelectron yield of the sample under test at different wavelengths and generate the ultraviolet photoelectron yield spectrum of the sample. Photoelectron emission yield at any wavelength... Y(λ) for:

[0097]

[0098] N e (λ) This represents the number of photoelectrons detected per second at the corresponding wavelength. k(λ) This represents the refraction ratio for the corresponding wavelength; N p (λ) This represents the number of photons detected per second at the corresponding wavelength. N pr (λ) The number of photons in the reference optical path corresponding to the wavelength. N pm (λ)This represents the number of photons in the main optical path corresponding to the wavelength. The number of photons in the main optical path is measured by translating the main optical path ultraviolet detector 11 to the four-dimensional sample operation stage 10.

[0099] The data storage module is used to store the counting results of the photon counter and the photoelectron counter, as well as the test results of the UPS test module and the PYS test module.

[0100] The ultraviolet photoelectron spectroscopy analyzer described in this application integrates high-accuracy yield spectroscopy analysis and high-resolution energy spectroscopy analysis. It can realize in-situ coupled analysis of ultraviolet photoelectron yield spectroscopy and energy spectroscopy in the same device, and cross-validate it. It avoids spatial position deviation and surface state changes caused by sample transfer between different devices. It can effectively solve the problem of distortion of the quantitative correspondence between yield spectroscopy and energy spectroscopy when traditional separate tests are performed. It is beneficial to obtain fine characterization of the electronic structure of the valence band on the material surface (especially in the low density state region) and can obtain the electronic structure characterization of the interstitial state of the material. It is of great significance for exploring the ultraviolet photoelectron emission mechanism of materials.

[0101] The gold standard sample was subjected to PYS and UPS tests using the ultraviolet photoelectron spectrometer provided in the embodiments of this application. The specific process is as follows: (1) Connect the equipment power supply and preheat the vacuum ultraviolet deuterium lamp for 20 minutes; (2) Place the gold standard sample on the sample holder in the injection chamber, and sequentially turn on the mechanical pump and molecular pump to evacuate to a vacuum of 3×10⁻⁶. -7 Pa; (3) Open the valve between the injection chamber and the analysis chamber, and transfer the gold standard sample to the four-dimensional sample operation table in the analysis chamber through the magnetic transfer rod. When the sample is placed in the specified position, retract the magnetic transfer rod into the injection chamber and close the valve. (4) Set the incident light wavelength to 0 nm using a vacuum ultraviolet monochromator, and adjust the incident and exit slits of the vacuum ultraviolet monochromator to 0.5 mm in sequence to confirm that the light spot is focused at the center of the sample. (5) Set the incident wavelength of the vacuum ultraviolet monochromator to 115nm, turn on the high voltage power supply of the channel electron multiplier, set the input / output / anode voltage to 500V / 1900V / 2100V respectively, set the scanning step size of the vacuum ultraviolet monochromator to 1nm, the scanning range to 115nm~400nm, and set the bias voltage of the photoelectron counter to 11meV. (6) Perform PYS testing; (7) After obtaining the PYS spectrum, reduce the input / output / anode voltage of the channel electron multiplier to 0V in sequence and turn off the high voltage power supply; Adjust the output wavelength of the vacuum ultraviolet monochromator to 161nm, set the bias voltage of the four-dimensional sample operation stage to -10V, and set parameters such as the power supply voltage of the hemispherical energy analyzer, the voltage of the two-dimensional electron imaging detector, the scanning step size, the exposure time, the number of images acquired, and the gated kinetic energy. The fluorescent screen is imaged by exposure through an industrial camera, and the images are acquired and processed in segments according to the magnitude of the electron kinetic energy. The images are superimposed and integrated at the same kinetic energy to obtain UPS data. (9) Gradually reduce the pressure of the hemispherical energy analyzer and the two-dimensional electron imaging detector, turn off the power supply of the equipment in sequence, turn off the ultraviolet light source, transfer the gold sample to the sample chamber through the magnetic transmission rod, turn off the molecular pump and mechanical pump in sequence, and when the gas pressure in the sample chamber returns to atmospheric pressure, open the sample chamber and transfer the gold sample to the drying cabinet for storage.

[0102] This application also proposes an in-situ coupled ultraviolet photoelectron yield spectroscopy and energy dispersive spectroscopy analysis method, applied to the ultraviolet photoelectron spectroscopy analyzer described above. The method includes the following steps: Under the same vacuum environment and without moving the spatial position of the sample under test, the first test mode and the second test mode are executed respectively. The first test mode is the ultraviolet photoelectron yield spectrum test mode: a monochromatic ultraviolet light with a continuously tunable wavelength is generated by a monochromatic light generation system and irradiated onto the surface of the sample to be tested; the intensity of the incident light is monitored by an ultraviolet detector in the reference optical path; the entrance of the multi-stage incident lens is closed; and the number of photoelectrons emitted by the sample at different wavelengths is detected by a channel electron multiplier to generate an ultraviolet photoelectron yield spectrum. The second test mode is the ultraviolet photoelectron spectroscopy test mode: monochromatic ultraviolet light of a fixed wavelength is generated by the monochromatic light generation system and irradiated onto the surface of the sample to be tested; the entrance of the multi-stage incident lens is opened; the energy and momentum distribution of the emitted photoelectrons are detected by the hemispherical energy analyzer and the two-dimensional electron imaging detector to generate an ultraviolet photoelectron spectrum; Based on the test results of the first test mode and the second test mode, the electronic structure physical parameters of the sample under test are cross-validated.

[0103] Specifically, in this embodiment, both the first test mode (PYS test mode) and the second test mode (UPS test mode) are performed in the same vacuum environment and at the same test station. The two test modes are executed separately, meaning they are performed sequentially, either first (PYS test mode) followed by second (UPS test mode), or vice versa. Maintaining the spatial position and vacuum environment of the sample in both tests ensures consistency in the sample surface state, avoiding distortion of the quantitative correspondence between the yield spectrum and energy spectrum, reducing test errors, and improving test accuracy.

[0104] Optionally, in the first test mode, during the acquisition window, the high voltage of the channel electron multiplier is turned on and the electronic shutter is opened; during the non-acquisition window, the high voltage is turned off and the shutter is turned off; in the second test mode, the electronic shutter is kept open, the high voltage of the channel electron multiplier is turned off, and the high voltage of the hemispherical energy analyzer is turned on.

[0105] Figure 5 This is a schematic diagram illustrating the steps of an in-situ coupled ultraviolet photoelectron spectroscopy-energy dispersive spectroscopy analysis method according to an embodiment of this application, as shown below. Figure 5 As shown, the method includes: Step S11: Measure the photoelectron yield emitted by the sample under test at multiple different wavelength points to obtain the photoelectron yield spectrum of the sample under test. The multiple different wavelength points belong to the vacuum ultraviolet band. The horizontal axis of the photoelectron yield spectrum is the photon energy corresponding to the wavelength point, and the vertical axis is the photoelectron yield.

[0106] The vacuum ultraviolet band refers to the spectrum with wavelengths in the range of 10nm to 200nm, which is a subrange of the ultraviolet spectrum. Because the photon energy in this band is relatively high, it can excite the surface of materials to generate photoelectrons. Therefore, this band is selected as the test light source in this embodiment.

[0107] Photoelectron yield is defined as the number of photoelectrons emitted from the surface of a sample excited by each incident photon. The sample can be a gold-labeled sample. This application transforms the complex photoelectron yield spectroscopy measurement into an efficient and repeatable operation through standardized procedures and automated control, laying the data foundation for the entire HOMO level measurement method.

[0108] In an optional implementation, step S11 specifically includes steps S111 to S115: Step S111: The monochromatic light in the vacuum ultraviolet band is split into a main light path for transmission and a reference light path for reflection at multiple different wavelength points.

[0109] Please see Figure 1Multiple different wavelength points are selected by the vacuum ultraviolet monochromator 4 within the vacuum ultraviolet band using a preset step size. At each wavelength point, the light source beam is split into two independent optical paths by the beam splitter 7. One is the transmitted main optical path, which directly illuminates the surface of the sample under test and is used to excite photoelectrons. The other is the reflected reference optical path, which serves as a reference signal for real-time monitoring of the light source stability and does not participate in the excitation of the sample under test. A reflecting mirror is located behind the beam splitter 7 (along the direction of the main optical path) and before the sample stage. It is used to change the propagation direction of the transmitted main optical path, guiding the monochromatic beam transmitted through the beam splitter 7 to the focusing lens 9 and finally illuminating the surface of the sample under test on the sample stage. This ensures the spatial directivity of the main optical path beam.

[0110] In practice, the first step is to control the vacuum ultraviolet deuterium lamp 1-1 to generate a continuous ultraviolet spectrum covering the vacuum ultraviolet band. The deuterium lamp is a commonly used ultraviolet light source, particularly suitable for providing high-brightness and highly stable ultraviolet spectra. Because it can produce a broad wavelength range from 160nm to 400nm, the deuterium lamp provides a relatively uniform ultraviolet spectrum for the experiment. In practice, the deuterium lamp is started to emit light by adjusting the power supply and control system. During the emission process, the deuterium lamp can produce continuous ultraviolet light within the vacuum ultraviolet band.

[0111] The ultraviolet light beam from the vacuum ultraviolet deuterium lamp is reflected onto the filter 3 using a ring mirror 2. The ring mirror is an optical element used to reflect and guide the light beam in the optical path. Its shape is designed to ensure that the beam remains relatively concentrated and uniform after reflection by the ring mirror. The main function of the ring mirror is to concentrate the ultraviolet light emitted by the deuterium lamp and guide it to the filter for further processing.

[0112] For each specific wavelength point among multiple different wavelength points, stray light from non-specific wavelength points in the beam reflected by the annular mirror is filtered out using filter 3, resulting in a filtered beam. The filter is used to remove stray light from the ultraviolet beam reflected from the annular mirror, retaining only the light at the specific wavelength point. Stray light refers to excess spectral components outside the specific wavelength range, which may affect subsequent measurements. The filter is made of a special material that allows light to pass through within a specific wavelength range while absorbing or reflecting light of other wavelengths. Through precise design and selection of the filter, it can be ensured that only monochromatic light matching the specific wavelength point passes through, while other wavelength components are effectively blocked by the filter. The filtered beam has a relatively uniform wavelength distribution, ensuring that the light source outputs monochromatic light close to the specific wavelength. The choice of filter depends on the specific requirements of the specific wavelength; for example, a bandpass filter (allowing the target wavelength band while blocking other wavelength bands) or a high-pass / low-pass filter (allowing light greater than or less than the specific wavelength, respectively) can be used.

[0113] The ultraviolet beam, after being processed by the filter, is fed into the vacuum ultraviolet monochromator 4, where it is further filtered and output as monochromatic light of a specific wavelength. A vacuum ultraviolet monochromator is a device capable of separating and outputting a specific wavelength from the spectrum; its core working principle is based on the dispersion effect of light. The vacuum ultraviolet monochromator contains optical elements such as gratings, lenses, or prisms to separate light of different wavelengths. By adjusting the angle of the grating, the desired wavelength is selected. After the filtered beam emitted by the deuterium lamp enters the monochromator, the optical elements selectively separate the light of the desired wavelength according to a preset specific wavelength point, while other components outside the specific wavelength range are filtered out. Through this process, the vacuum ultraviolet monochromator can output precise monochromatic light of a specific wavelength for subsequent experiments or measurements.

[0114] The focusing lens 9 uses an off-axis parabolic mirror with a specific numerical aperture to focus the ultraviolet parallel (or quasi-parallel) beam of light with a certain divergence angle output from the ultraviolet monochromator slit into a small spot on the micrometer scale, which is then precisely illuminated at the test point of the sample.

[0115] Step S112: Measure the number of incident photons in the reference optical path at each wavelength point, and measure the number of incident photons in the main optical path at each wavelength point.

[0116] For each of multiple different wavelength points, a photomultiplier tube is used to measure the wavelength at that point. Below, the number of incident photons in the reference optical path A photomultiplier tube is a highly sensitive detector that converts incident photons into electronic signals and amplifies these electronic signals through a multiplication process, thereby enabling the detection of low-intensity signals.

[0117] Whenever a photon is absorbed by the photocathode of a photomultiplier tube, it releases electrons. These electrons are multiplied through multiple electrodes inside the photomultiplier tube, eventually generating a measurable current signal.

[0118] During this process, the photomultiplier tube counts each incident photon and converts the number of photons into a corresponding electronic signal, facilitating subsequent data processing and analysis. By comparing the output signal of the photomultiplier tube with a preset exposure period, the number of photons entering the reference optical path within a specific time period can be accurately calculated.

[0119] The sample to be tested is supported by a sample stage, and its spatial position is adjusted so that the main optical path is focused on the surface of the sample. Exposure is controlled by the electronic shutter 8 according to a preset exposure cycle. The electronic shutter adjusts the incident time of light, thereby precisely controlling the exposure duration and ensuring consistency in exposure time for each exposure. During this process, the light source in the main optical path begins to illuminate the sample under the control of the electronic shutter, and after a preset time, the shutter closes, stopping the exposure.

[0120] During the exposure in the main optical path, a wide-bandgap semiconductor photodetector mounted on a movable support is used to measure the number of incident photons that illuminate the surface of the sample under test through the main optical path at the location of the sample stage. The photodetector uses a wide bandgap semiconductor material, which exhibits excellent photoelectric response characteristics in the vacuum ultraviolet band, enabling it to effectively detect photon signals in the main optical path. The working principle of the wide bandgap semiconductor photodetector is to absorb photons and convert them into an electrical signal to measure the photon count. Due to the high bandgap of wide bandgap semiconductor materials, they exhibit strong photoelectric effects in the ultraviolet, visible, and near-infrared bands, effectively detecting photon signals within specific wavelength ranges. The wide bandgap semiconductor photodetector is mounted on a movable stand, allowing its position to be adjusted according to experimental needs. Once the relative positions of the sample stage and the photodetector are adjusted, the detector can accurately receive incident photons in the main optical path at specific wavelengths and convert them into measurable electrical signals.

[0121] Step S113: Calculate the splitting ratio at each wavelength point based on the number of incident photons in the main optical path and the number of incident photons in the reference optical path at each wavelength point.

[0122] spectral ratio This refers to a specific wavelength point. Below, the number of incident photons detected by the reference optical path The number of incident photons detected by the main optical path The ratio between them. Its mathematical expression is:

[0123] spectral ratio This reflects the beam splitter's position at the target wavelength. The optical beam-splitting characteristics (reflectivity to transmittance ratio) at a given wavelength. The reflection / transmission performance of a beam splitter may differ at different wavelengths, therefore... It is a function of wavelength. The splitting ratio also implicitly includes the difference in wavelength between the reference optical path detector (photomultiplier tube PMT) and the main optical path detector (wide bandgap semiconductor photodetector). The relative response sensitivity difference at the location. Although the detector has been calibrated, The measured values ​​contain overall state information of the system at that wavelength.

[0124] Step S114: Measure the number of photoelectrons excited by the main optical path on the surface of the sample under test at each wavelength point.

[0125] For each of the multiple different wavelength points, the weak photoelectron signal excited from the surface of the sample under test is amplified by an electron multiplier. An electron multiplier is a precision electronic device that enhances the photoelectron signal emitted from the sample surface by applying a high-voltage electric field, making it more prominent and easier for subsequent counting. An electron multiplier typically consists of multiple multiplier tubes, each containing a cathode and multiple gain electrodes. Electrons generated by the photoelectric effect first strike the cathode of the multiplier, releasing primary electrons. These primary electrons are then accelerated and strike the gain electrodes in the multiplier, generating more secondary electrons. This process is repeated continuously at the multiple gain electrodes of the electron multiplier, ultimately amplifying the weak photoelectron signal into a sufficiently strong electrical signal. By applying a high-voltage electric field, the electron multiplier can control the acceleration and collision process of electrons, effectively amplifying the photoelectron signal.

[0126] In practice, by setting the step size and scanning range of the vacuum ultraviolet monochromator, and turning on the high-voltage power supply of the electron multiplier (for example, the input / output / anode voltages are set to 500V / 1900V / 2100V respectively), the incident light is continuously adjusted to obtain continuous and different wavelength points, and the number of incident photons and photoelectrons collected at each wavelength point is recorded.

[0127] The number of photoelectrons excited by the main optical path on the surface of the sample under test is obtained by accurately measuring the photoelectron signal amplified by the electron multiplier using a pulse counter.

[0128] A pulse counter is a high-precision counting device. Its working principle is to convert the electrical signal amplified by an electron multiplier into a pulse signal. Each time a photoelectron passes through the counter, the counter records a pulse. These pulse signals are digitized and analyzed by a computer system. The pulse counter ultimately outputs the measured number of photoelectrons. That is, the number of photoelectrons excited on the surface of the sample by the main optical path. .

[0129] In an optional implementation, an embodiment of this application provides a material ionization potential measurement system based on photoelectron yield spectrum, which further includes a helium lamp 16 and a neutralizing electron gun 12. Helium lamp 16 is the calibration light source in the vacuum ultraviolet band. In this embodiment, helium lamp 16 serves as the incident light source, with an energy of 21.2 eV, corresponding to a wavelength of approximately 58.5 eV. Neutralizing electron gun 12 is located near the sample stage. To achieve electron neutralization on the surface of the insulating material, neutralizing electron gun 12 emits a low-energy electron beam to neutralize the charge, ensuring that the photoelectron yield measurement is not interfered with and cleaning the sample surface before measurement. Argon ion gun 15 emits an argon ion beam to bombard the sample surface. This effectively removes contaminants (such as adsorbed gas molecules) or oxide layers from the sample surface, obtaining a clean, intrinsic surface state.

[0130] Step S115: Determine the photoelectron yield spectrum of the sample under test based on the splitting ratio at each wavelength point, the number of incident photons in the reference optical path, and the number of photoelectrons.

[0131] First, based on the pre-measured splitting ratio (the ratio of the number of incident photons in the reference path to the number of incident photons in the main path) at each wavelength point, and the number of incident photons in the reference path at each wavelength point, the number of incident photons in the main path is corrected to obtain the actual number of incident photons reaching the sample surface. Then, the number of photoelectrons measured at each wavelength point is divided by the actual number of incident photons at the corresponding wavelength point to calculate the photoelectron yield value at each wavelength point, i.e., the number of photoelectrons excited by each incident photon. This process is repeated for all wavelength points to obtain a series of data points for photon energy and photoelectron yield values. Finally, a photoelectron yield spectrum curve is plotted with photon energy as the x-axis and photoelectron yield as the y-axis. The photoelectron yield spectrum curve reflects the photoelectric emission efficiency of the sample at different photon energies.

[0132] In an optional implementation, step S115 specifically includes steps S1151 to S1153: Figure 6 This is a graph showing the photoelectron yield spectrum test results of a gold sample in one embodiment of this application. Please refer to [link / reference]. Figure 6 This application constructs a photoelectron yield spectrum (PYS) by integrating optical parameters and photoelectron data. Specifically, it constructs a PYS based on specific incident wavelengths. Converted into corresponding photon energy The formula corresponding to the abscissa of the photoelectron yield spectrum is:

[0133] In the formula, is Planck's constant. It is the speed of light.

[0134] Calculate optoelectronic output The formula corresponding to the vertical axis of the photoelectron yield spectrum is:

[0135] in,

[0136] therefore:

[0137] Step S1151: Based on the splitting ratio at each wavelength point, correct the number of incident photons in the main optical path at the corresponding wavelength point to obtain the actual number of incident photons in the main optical path at each wavelength point.

[0138] As mentioned earlier, during actual measurements, the output intensity of the vacuum ultraviolet deuterium lamp may fluctuate or drift slightly over time. This is because the photons in the reference and main optical paths originate from the same light source pulse (after beam splitting). and They fluctuate proportionally. This proportional relationship is provided. In subsequent calculations of the actual number of photons irradiating the sample surface, Divide by The actual number of photons reaching the sample surface can then be obtained. More importantly, in subsequent measurements of the number of photoelectrons in the sample under test... In this way, it is not necessary to move the photodetector to the sample position for measurement every time. Simply at each wavelength point Real-time measurement reference optical path And using the pre-determined wavelength point The number of photons actually reaching the sample surface at this moment and wavelength can be calculated using the following formula. That is, the actual number of incident photons in the main optical path:

[0139] In this way, even if the light source intensity fluctuates during the scanning process, the actual number of photons excited in the sample at each wavelength point can be accurately determined, thus ensuring the photoelectron yield. The accuracy of the calculations eliminates systematic errors caused by the instability of the light source.

[0140] Step S1152: Divide the number of photoelectrons at each wavelength point by the actual number of incident photons at the corresponding wavelength point to obtain the photoelectron yield value at each wavelength point.

[0141] Optoelectronic output ( The photoemission efficiency (PAE) is defined as the number of photoelectrons excited by each incident photon, reflecting the photoemission efficiency of a material at a specific wavelength. The calculation formula is:

[0142] Step S1153: Based on the photoelectron yield values ​​at the multiple different wavelength points, obtain the photoelectron yield spectrum of the sample to be tested.

[0143] Multiple wavelengths ( , ,…, optoelectronic output under ) Sort by photon energy hv to form a dataset:

[0144] The horizontal axis represents photon energy ( The y-axis represents photoelectron yield (Y, photoelectrons / photons), and the y-axis represents photoelectron yield. A photoelectron yield spectrum curve is plotted. Figure 3 In the figure, the curve extending from 0 eV to 6 eV is the measured curve of the photoelectron yield spectrum of the gold standard sample.

[0145] Step S12: At the target wavelength point, measure the photoelectron momentum and energy information emitted by the sample to be tested to obtain the ultraviolet photoelectron spectrum of the sample to be tested. The target wavelength point belongs to the vacuum ultraviolet band. The horizontal axis of the ultraviolet photoelectron spectrum is the binding energy, and the vertical axis is the photoelectron intensity.

[0146] The ultraviolet photoelectron spectrum is constructed by irradiating the sample with a photon beam at a target wavelength and analyzing the distribution of photoelectrons excited in the sample. A photon beam refers to electromagnetic radiation with a specific wavelength, belonging to the vacuum ultraviolet band, specifically ultraviolet radiation with wavelengths ranging from approximately 10 nm to 200 nm. The photon beam interacts with the sample, exciting electrons within the sample and causing them to escape from the surface, thus generating photoelectrons.

[0147] During photoelectron emission, each photoelectron absorbs different amounts of energy when interacting with a photon, resulting in different kinetic and binding energies, which can reveal characteristics of the sample's internal electronic structure. Therefore, binding energy and the corresponding photoelectron intensity are two important dimensions of the ultraviolet (UV) photoelectron spectrum, represented as the abscissa and ordinate, respectively. Specifically, the UV photoelectron spectrum is obtained by measuring the kinetic energy distribution of photoelectrons emitted from the sample. Photoelectrons are excited from the sample by irradiating its surface with a photon beam from the vacuum ultraviolet region. By measuring the photoelectron kinetic energy and displaying it in the UV photoelectron spectrum, the abscissa represents the binding energy, and the ordinate represents the corresponding photoelectron intensity, i.e., the number of photoelectrons detected at a given kinetic energy. Figure 7 This is a graph showing the ultraviolet photoelectron spectroscopy (UVP) results of a gold sample in one embodiment of this application. Figure 7The horizontal axis in the diagram represents the binding energy. When the photoelectron kinetic energy is higher, it means that it gains more energy and requires less binding energy, thus resulting in a lower binding energy. Conversely, when the photoelectron kinetic energy is lower, the binding energy is higher.

[0148] After obtaining the photoelectron yield spectrum of the sample to be tested, the input / output / anode voltages of the single-channel electron multiplier were sequentially reduced to 0V, and the high-voltage power supply was turned off. The output wavelength of the vacuum ultraviolet monochromator was adjusted to 161nm using software, and the sample stage bias voltage was set to -10V. Parameters such as the scan step size, electron focusing lens, and hemispherical energy analyzer voltage were also set to prepare for testing the ultraviolet photoelectron spectrum of the sample to be tested.

[0149] In an optional implementation, step S12 specifically includes steps S121 to S125: Step S121: Irradiate the sample to be tested with a photon beam of the target wavelength to obtain photoelectrons with different kinetic energies excited by the sample to be tested.

[0150] A prepared beam of photons at the target wavelength is irradiated onto the surface of the sample under test. When the photon beam interacts with the sample surface, it transfers energy to electrons within the sample. These electrons are excited, and after gaining sufficient energy, they detach from the sample surface, forming photoelectrons. As mentioned earlier, since each photoelectron gains different amounts of energy when absorbing photons, their kinetic energies will also differ.

[0151] Step S122: Using a hemispherical energy analyzer, photoelectrons with different kinetic energies are screened from the photoelectrons with different kinetic energies excited by the sample to be tested.

[0152] A hemispherical energy analyzer is used to screen photoelectrons emitted from the surface of the sample. The hemispherical energy analyzer is a common instrument for electron energy analysis. Its working principle is to separate the electron beam according to its kinetic energy using a combination of electric and magnetic fields. It consists of two hemispherical electrodes. After the photoelectron beam enters the hemispherical energy analyzer, the electric field between the electrodes separates the electrons according to their energy. By adjusting the strength of the electric field, photoelectrons with different kinetic energies can be screened. The hemispherical energy analyzer can measure the kinetic energy of photoelectrons and select photoelectrons within a specific kinetic energy range, which helps in the subsequent construction of a complete ultraviolet photoelectron spectrum, revealing the energy distribution of electrons in the sample. The electron incident lens is located between the sample stage and the hemispherical energy analyzer. Its main function is to guide and initially focus the photoelectron beams with different kinetic energies emitted from the surface of the sample under test. By applying a specific electric field, it can effectively converge the dispersed photoelectrons, increasing the electron flux entering the subsequent hemispherical energy analyzer, thereby enhancing signal strength and measurement accuracy.

[0153] Step S123: The signals of photoelectrons with different kinetic energies are amplified through a microchannel plate, and corresponding light emission images are obtained on a fluorescent screen. The light emission images include pixels at multiple different positions.

[0154] The signals of photoelectrons with different kinetic energies, filtered by a hemispherical energy analyzer, are amplified by a microchannel plate. A microchannel plate is a device composed of a series of tiny channels. Its working principle is that when photoelectrons flow through these channels, they excite the internal material to release secondary electrons, thereby amplifying the original photoelectron signal. This process significantly increases the signal intensity, allowing even weak photoelectron signals to be further detected and analyzed. The amplified photoelectron signal is displayed on a fluorescent screen as a light emission image. This light emission image on the fluorescent screen is generated by the light emission produced when photoelectrons collide with fluorescent material. Each luminous point on the screen corresponds to the detection signal of a photoelectron. Each luminous point represents an electron signal at a different location.

[0155] Step S124: Using an industrial camera, the light emission image is captured in segments according to the photoelectric kinetic energy.

[0156] An industrial camera is used to capture images of the luminescence emitted on a fluorescent screen. This high-resolution, highly stable camera accurately captures the position and brightness of each luminous point on the screen. Each frame represents the luminescence under different kinetic energies, containing the brightness and position of each pixel, further improving measurement accuracy and data integrity.

[0157] Step S135: Superimpose all the light-emitting images captured by the industrial camera and integrate the pixels with the same electron kinetic energy to obtain the ultraviolet photoelectron spectrum of the sample to be tested.

[0158] The purpose of overlaying all the luminescent imaging images captured by industrial cameras is to combine information from multiple images to obtain more comprehensive signal data, ensuring that no details are missed. Please see... Figure 7 After overlaying the images, the number of photoelectrons at each kinetic energy value is obtained by integrating the pixels with the same photoelectron kinetic energy, i.e., the photoelectron intensity. The resulting ultraviolet photoelectron spectrum reflects the energy distribution of photoelectrons in the sample. Figure 7 The curve with the peak shape is the measured ultraviolet photoelectron spectrum curve of the gold standard sample.

[0159] Step S13: Determine the ionization potential of the sample to be tested based on the photoelectron yield spectrum, and determine the work function of the sample to be tested based on the ultraviolet photoelectron energy spectrum.

[0160] To determine the ionization potential of a sample, the ionization potential is calculated by analyzing the photoelectron yield spectrum and its fitted curve. In practice, firstly, a horizontal baseline with a photoelectron yield of zero is determined from the photoelectron yield spectrum; secondly, the fitted curve is extended to intersect this horizontal baseline, and the photon energy value corresponding to the intersection point is the ionization potential of the sample. This application combines intuitive analysis of experimental data with precise calculation through mathematical fitting, ensuring the accuracy and reliability of the ionization potential measurement.

[0161] For determining the work function of the sample, the energy value of the secondary electron cutoff edge is extracted. According to the principle of energy conservation in photoelectric emission, the work function is equal to the incident photon energy at the target wavelength point minus the determined secondary electron cutoff edge energy value. As mentioned earlier, the photon energy at the target wavelength point can be calculated based on its wavelength value.

[0162] In an optional implementation, step S13 specifically includes steps S131 to S133: Step S131: Select the corresponding power function model based on the material type of the sample to be tested.

[0163] Based on the physical category of the sample to be tested, the exponent m value is retrieved from a preset rule. Please refer to Table 1 for an example of the preset rule:

[0164] Users can select the material category, match the m-value, and embed it into the model through the software interface. (C is the proportionality coefficient).

[0165] In an optional implementation, step S131 specifically includes steps S1311 to S1312: Step S1311: Determine the excitation type and scattering type of the sample to be tested based on the material type of the sample to be tested.

[0166] The electron emission behavior of a material is determined by its physical properties, which must be considered in conjunction with the following characteristics: material type, microstructure, and electronic state properties. As shown above, the user inputs the material type and structural parameters of the sample to be tested through the software interface, and based on this, the excitation type and scattering type are determined (e.g., inputting "direct bandgap semiconductor and high defect concentration" will output "direct optical excitation and elastic scattering").

[0167] Step S1312: Define the corresponding exponent value for the power function model based on the excitation type and scattering type of the sample to be tested.

[0168] Based on the rules shown in Table 1, the output results are mapped to the exponent m. For example, if the input material type is metal and the excitation type is bulk emission, the scattering type is determined to be elastic scattering, and m=2 is determined.

[0169] Step S132: Based on the power function model, perform polynomial fitting calculation on the starting region of the rising edge of the photoelectron yield spectrum to obtain the fitting curve.

[0170] In the photoelectron yield spectrum, a polynomial fitting is performed on the rising edge initiation region, and a portion is extracted from the yield spectrum. The first significant increase in a continuous interval linearizes the power function relationship:

[0171] by As the independent variable, Optimize parameters as dependent variable The ionization potential IP is used to generate the fitted curve.

[0172] In an optional implementation, step S132 specifically includes: using a nonlinear least squares fitting algorithm, based on the exponent value defined by the power function model, to perform polynomial function fitting on the photon energy and photoelectron emission yield of the data points in the starting region, and obtain the fitting curve.

[0173] As mentioned earlier, optoelectronic output With photon energy The relationship is:

[0174] In the photoelectron yield spectrum, only the initial segment of the rising edge (i.e., the initial curve region where the yield increases from zero) is selected, excluding interfering data from the high-energy segment. A least-squares optimization algorithm is used to substitute the yield data and photon energy data into a preset power function model. Specifically, while maintaining the previously selected exponent values, the ionization potential and proportionality coefficient are adjusted. Through error minimization calculations, the fitted curve is made to fit the measured data points as closely as possible, and the final output fitted curve is obtained upon convergence.

[0175] Step S133: Determine the ionization potential of the sample to be tested based on the photoelectron yield spectrum and the fitted curve.

[0176] The ionization potential of the sample is calculated by analyzing the photoelectron yield spectrum and its fitted curve. In practice, firstly, a horizontal baseline with a photoelectron yield of zero is determined from the photoelectron yield spectrum; secondly, the fitted curve is extended to intersect this horizontal baseline, and the photon energy value corresponding to the intersection point is the ionization potential of the sample. This application combines intuitive analysis of experimental data with precise calculation through mathematical fitting, ensuring the accuracy and reliability of the ionization potential measurement.

[0177] In an optional implementation, step S133 specifically includes steps S1331 to S1333: Step S1331: Determine the horizontal baseline with a photoelectron yield value of zero from the ultraviolet photoelectron yield spectrum through data processing.

[0178] In this embodiment, the horizontal baseline represents the reference state where, theoretically, the photoelectron yield should be zero when the photon energy is below the material ionization potential. However, in actual measurements, due to factors such as electronic noise, stray light interference, or detector dark counting, the measured photoelectron yield value may exhibit a slight non-zero background. Therefore, this application proposes to objectively determine the horizontal baseline from the ultraviolet photoelectron yield spectrum using data processing methods.

[0179] Specifically, for the acquired ultraviolet photoelectron yield spectrum curves, the energy range where the photon energy is significantly lower than the estimated ionization potential was selected. Within this range, the photoelectron yield changes very little with photon energy, theoretically approaching zero. Statistical analysis was performed on all photoelectron yield data points within this range, and the calculated results were used as the horizontal baseline of the ultraviolet photoelectron yield spectrum. The horizontal baseline represents the background noise level of the system under the current experimental conditions.

[0180] Step S1332: Based on a preset power function model related to the material type of the sample to be tested, the rising edge starting region of the ultraviolet photoelectron yield spectrum is fitted to obtain a fitting curve.

[0181] According to the photoelectric emission theory, near the ionization potential threshold, the photoelectron yield Y and the incident photon energy hv satisfy a power-law relationship. Different materials (such as metals, inorganic semiconductors, and organic semiconductors) and different photoelectron emission processes (such as bulk emission, surface emission, direct / indirect optical excitation, and elastic / inelastic scattering) correspond to different values ​​of m.

[0182] Based on the photoelectron emission process of the sample under test, the exponent m value is retrieved from a preset rule. See Table 1 for an example of the preset rule:

[0183] Users can select the material category, match the m-value, and embed it into the model through the software interface. (C is the proportionality coefficient).

[0184] In the ultraviolet photoelectron yield spectrum, the rising edge initiation region was selected, i.e., the continuous interval where the photoelectron yield first shows a significant increase from near the horizontal baseline. A nonlinear least squares fitting algorithm was used to fit the data points (photon energy, photoelectron yield) within this region based on the determined power function model. A linear fit was performed with photon energy as the independent variable and photoelectron yield as the dependent variable to obtain the fitted curve. The fitted curve describes the trend of photoelectron yield with photon energy near the ionization potential threshold.

[0185] Step S1333: Extend the fitted curve towards the direction of low photon energy, calculate its intersection with the horizontal baseline, and determine the photon energy value corresponding to the intersection as the ionization potential of the sample to be tested.

[0186] Shift the fitted curve towards lower photon energy ( Figure 3 Extend the curve to the left of the horizontal axis and calculate its intersection with the horizontal baseline. Since the horizontal baseline represents the benchmark where the photoelectron yield is zero, and the fitted curve represents the growth behavior of the yield near the threshold, the intersection of the two physically corresponds to the minimum photon energy, i.e., the ionization potential, at which the material just begins to emit photoelectrons.

[0187] In practice, a horizontal baseline and a fitted curve can be plotted in the same coordinate system. By using analytical solutions or numerical approximation methods, the photon energy value corresponding to the point where the function value of the fitted curve equals the value of the horizontal baseline can be found; this intersection point is the ionization potential.

[0188] Please see Figure 6 The horizontal baseline is taken from the low-energy region of the photoelectron yield spectrum, representing the mean background noise when there is no photoelectron emission. The experimental data points are the measured yield values ​​in the rising edge initiation region. The fitted curve is the result of power function fitting of the data points. Figure 6 The spectrum is shown as tangent to the measured photoelectron yield spectrum of the gold sample. The final determined ionization potential (IP) is the photon energy corresponding to the intersection of the fitted curve and the horizontal baseline.

[0189] In an optional implementation, step S13 specifically includes steps S134 to S135: Step S134: Determine the secondary electron cutoff edge energy value from the ultraviolet photoelectron spectrum.

[0190] After acquiring ultraviolet photoelectron spectroscopy (UPS) data, a steep rising edge signal is identified from the low kinetic energy end (corresponding to the high binding energy end) of the ultraviolet photoelectron spectrum. This corresponds to the critical position where the kinetic energy of the secondary electrons emitted from the material surface approaches zero, i.e., the secondary electron cutoff edge.

[0191] In an optional implementation, step S134 specifically includes steps S1341 to S1344: Step S1341: The ultraviolet photoelectron spectrum is processed using a digital filtering algorithm to obtain the noise-reduced ultraviolet photoelectron spectrum and the noise intensity level line.

[0192] Optionally, a Savitzky-Golay filter can be used to analyze the raw ultraviolet photoelectron spectrum data points. For smoothing, the filtering formula is:

[0193] in, Represents the kinetic energy of photoelectrons. For channel index, The energy intensity of the ultraviolet photoelectron spectrum after noise reduction. This is the width of the filter window. For the order of the polynomial Determined filter coefficients, .

[0194] Calculate the standard deviation of photoelectron intensity in the low-signal region (high binding energy end) of the ultraviolet photoelectron spectrum. :

[0195] in, The average photoelectron intensity in the low-signal region. Given the number of data points, the noise intensity level can be defined as the standard deviation. Integer multiples, for example:

[0196] Step S1342: Determine the linear variation region containing the secondary electron cutoff edge from the denoised ultraviolet photoelectron spectrum.

[0197] From the denoised ultraviolet photoelectron spectrum, a linear variation region containing the secondary electron cutoff edge was identified. The secondary electron cutoff edge refers to the characteristic boundary of the ultraviolet photoelectron spectrum formed by the ionization of the sample during the emission of photoelectrons from the sample surface. Typically, before the secondary electron cutoff edge, the photoelectron kinetic energy is high; as the kinetic energy decreases, the photoelectron intensity gradually decreases, forming a distinct "cutoff" region. In the denoised ultraviolet photoelectron spectrum, the secondary electron cutoff edge shows an abrupt or sharp decrease. The linear variation region refers to the energy segment of the ultraviolet photoelectron spectrum near the secondary electron cutoff edge, where the photoelectron intensity exhibits a clear linear trend with increasing (or decreasing) photoelectron kinetic energy.

[0198] In an optional implementation, step S1342 specifically includes steps S13421 to S13423: Step S13421: Calculate the first derivative of the denoised ultraviolet photoelectron spectrum to obtain the derivative curve.

[0199] By calculating the first derivative of the denoised ultraviolet photoelectron spectrum, this study aims to reveal the regions of most significant change in the spectrum, especially the abrupt changes near the secondary electron cutoff edge. It can also identify the rate of change of photoelectron kinetic energy with energy.

[0200] Specifically, the photoelectron intensity corresponding to each photoelectron kinetic energy is extracted from the denoised ultraviolet photoelectron spectrum. The first derivative of the spectrum data is calculated using numerical differentiation methods, reflecting the rate of change of photoelectron intensity relative to photoelectron kinetic energy. Common numerical methods, such as the central difference method or the forward difference method, can be used to calculate the first derivative.

[0201] The derivative curve representing the rate of change of photoelectron intensity is calculated. The derivative curve can show regions with large changes in the energy spectrum, such as abrupt changes near the secondary electron cutoff edge.

[0202] Step S13422: From the derivative curve, the point on the horizontal axis corresponding to the photoelectron kinetic energy where the absolute value of the derivative first exceeds a preset threshold is determined as the starting point.

[0203] By analyzing the derivative curve, the starting point of the abrupt change in the rate of change of photoelectron intensity can be found, that is, the point where the absolute value of the derivative first exceeds the preset threshold, which is located at the forefront of the secondary electron cutoff edge.

[0204] The preset threshold, usually determined empirically or experimentally, represents the upper limit of the rate of change in photoelectron intensity. The absolute value of the derivative is calculated point-by-point from the derivative curve. When the absolute value of the derivative first exceeds the preset threshold, it indicates a significant change in the rate of change of photoelectron kinetic energy, occurring near the secondary electron cutoff edge. This point is considered the starting point of the linear change region, and the photoelectron kinetic energy value corresponding to this starting point is used as the benchmark for subsequent linear fitting.

[0205] Step S13423: Using the starting point as a reference, extend a preset energy width range to the side with low photoelectron kinetic energy to obtain the linear change region.

[0206] Based on the starting point, towards the side with lower photoelectron kinetic energy, that is, the side with higher binding energy ( Figure 4 A predetermined energy range is extended to the left of the horizontal axis to define the linear variation region near the secondary electron cutoff edge. The specific width of the predetermined energy range depends on the specific requirements of the experiment and the characteristics of the sample; it is the range extended from the starting point towards the direction of lower photoelectron kinetic energy. Starting from the starting point, the predetermined energy range is extended towards the side with lower photoelectron kinetic energy. Within this range, the photoelectron intensity at the secondary electron cutoff edge will exhibit a significant linear change, reflecting the gradual escape process of secondary electrons.

[0207] The photoelectron intensity within the extended range should exhibit a linear relationship with the photoelectron kinetic energy. The linear region represents the ultraviolet photoelectron spectrum characteristics near the secondary electron cutoff edge.

[0208] Step S1343: Using the least squares method, the relationship between photon intensity and photoelectron kinetic energy in the linearly changing region is linearly fitted to obtain a fitted straight line.

[0209] The least squares method obtains the best-fit line by minimizing the sum of squared errors between the fitted line and the actual data points. By fitting data within a linearly varying region, the relationship between photoelectron intensity and photoelectron kinetic energy is described, providing a basis for subsequently determining the energy of the secondary electron cutoff edge. Specifically, the photoelectron kinetic energy and corresponding photoelectron intensity within the linearly varying region are selected and substituted into the least squares fitting model. The least squares method finds an optimal line that minimizes the sum of squared errors between this optimal line and the data points, thus obtaining the fitted line. Figure 7 The straight line that is tangent to the high and medium binding energy regions (low kinetic energy regions) is the fitted straight line.

[0210] Step S1344: Determine the intersection point of the fitted straight line and the noise intensity horizontal line, and determine the photoelectron kinetic energy corresponding to the intersection point as the secondary electron cutoff edge energy value.

[0211] By finding the intersection of the fitted straight line and the noise intensity horizontal line, we can determine the energy value of the secondary electron cutoff edge. The photoelectron kinetic energy value corresponding to the intersection point is the energy of the secondary electron cutoff edge, which is a key physical parameter in the ultraviolet photoelectron spectrum, representing the emission energy of the secondary electron.

[0212] The intersection of the fitted straight line and the noise intensity level line can be obtained by solving the equation. We obtained, among which, It is the intensity of the noise level horizontal line. It is the photoelectron kinetic energy corresponding to the intersection point.

[0213] Step S135: Calculate the work function of the sample under test based on the photon energy corresponding to the target wavelength point and the secondary electron cutoff edge energy value.

[0214] Based on the principle of energy conservation in the photoelectric emission process, the work function Defined by the following formula:

[0215] in,

[0216] The energy of the incident photon. h It is Planck's constant. c It's the speed of light. This represents the energy value of the secondary electron cutoff edge.

[0217] Step S14: Subtract the ionization potential from the work function to obtain the valence band top HOMO level of the sample to be tested.

[0218] After obtaining the ionization potential IP and work function W of the sample, the HOMO level of the sample is calculated using the following formula. :

[0219] Specifically, the ionization potential IP represents the transition of an electron from the top of the valence band (HOMO level) to the vacuum level. The required energy, i.e.:

[0220] The work function W represents the electron's movement from the Fermi level. transition to vacuum level The required energy, i.e.:

[0221] Combining the above relationships, we can obtain:

[0222] Due to the Fermi level The reference zero point is at absolute zero. Simplified to:

[0223] Based on the three-step photoelectric emission model, the light emission intensity N(hν, EB) of the emitted photoelectron with energy EB under the action of an incident photon with energy hv can be expressed as:

[0224] in, |M fi |、D i 、D f X, T These are the transition coefficient from the initial state to the final state, the initial state density, the final state density, the electron transport probability, and the surface emission coefficient, respectively. By adjusting the incident photon energy hv using a monochromator, and receiving emitted photoelectrons with a fixed kinetic energy, therefore... D f · X · T It is a constant, that is

[0225] Generally speaking, it is believed that | M fi | 2 ∝( hv )-5 .

[0226] Therefore, the light emission intensity N(hν, EB) can be expressed as:

[0227] in, D f This can be obtained directly through UPS testing, for common materials. X, T Numerous theoretical calculations and experimental measurements already exist. Therefore, by conducting a series of UPS tests at different incident energies, the initial electron density of states in this state can be obtained. D i .

[0228] Furthermore, after the three-step photoemission model, the number of photoelectrons emitted within the dx layer is:

[0229] in, N(E,hv) energy of the incident photon hv The corresponding number of excited electrons; α(hv) The light absorption coefficient is... N p 0 ( hv () represents the number of photons incident on the material surface; photoelectrons are subject to electron-electron, electron-phonon, and electron-impurity scattering during transport, and the scattering probability under the first-order approximation is exp[- X / L ( E )], L ( E The scattering length () represents the scattering depth, which is the escape depth in the case of a surface. Excited electrons migrate to the surface after scattering, overcome the surface barrier, and escape. (The last part, ")", is a common expression, but its meaning is unclear without further context. F ( hv The function is used to characterize it, and under the first-order approximation, it is assumed that... F ( hv )≈1.

[0230] Therefore, the experimentally measured photoelectron emission yield spectrum Y(hv) A functional relationship can be established with the electronic density of states; the photoelectron yield within the dx layer is:

[0231] This is considered F ( hv )≈1. Therefore, the photoelectron yield corresponding to the incident photon energy hv and the emitted photoelectron energy E is:

[0232] When the penetration depth of photons α -1( hv Much greater than the electron scattering length L ( E When ), the above formula can be simplified to Y ( E, hv )≈ L (E) N ( E, hv Because ultraviolet photoelectron emission spectroscopy collects all emitted photoelectrons, it is necessary to integrate the electron energy E.

[0233] in, E Let sv be the minimum kinetic energy of the emitted electron, and let the final state density, electron escape depth, and transition matrix elements vary with energy. E The change is very small, that is, the initial state electron density at this time. D i ( E-hv () represents the effective density of states N * ( E-hv ),then: or

[0234] Therefore, the effective electronic state density N * ( E It can generate output through photoelectron emission. Y ( hv (Regarding photon energy) hv Differentiation yields:

[0235] If all states at a certain energy have the same transition probability and the transition probability is independent of energy, then the effective density of states... N * ( E () equals the actual occupied state density N ( E ), i.e., the density of the first electronic states D i Therefore, the photoelectron emission yield spectrum can characterize the initial electronic state structure of a material, that is, the density of valence band states in the bulk of the material and the density of occupied states on the surface can be described by the derivative of the photoelectron emission yield with respect to photon energy.

[0236] This application achieves high-precision measurement of the highest occupied molecular orbital (HOMO) energy level of the valence band by combining photoelectron yield spectroscopy (PYS) and ultraviolet photoelectron spectroscopy (UPS). This directly solves the core problems of high equipment cost, complex operation, and poor adaptability to non-metallic materials in related technologies. Users only need to set the wavelength scanning range and parameters to automatically complete data acquisition and analysis, avoiding the cumbersome calibration and repeated high-vacuum environment adjustments required by traditional ultraviolet photoelectron spectroscopy (UPS) or X-ray photoelectron spectroscopy (XPS). By integrating the measurement of ionization potential (IP) and work function (W) into a single process, and through nonlinear fitting and real-time data processing, rapid result output is achieved. Compared with traditional technologies, this shortens the measurement time and supports wide applicability to various material forms such as powders and thin films. While improving accuracy and stability, it fundamentally reduces systematic errors and operational uncertainties caused by equipment complexity.

[0237] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, electronic devices, and media. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of a computer program product embodied on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0238] This application describes embodiments of methods and apparatus according to flowchart illustrations and / or block diagrams. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing terminal equipment to cause a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0239] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0240] It should also be noted that, in this document, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as indicating or implying relative importance. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. In the absence of further restrictions, an element defined by the phrase "includes a..." does not preclude the presence of other identical elements in the process, method, article, or terminal device that includes the element.

[0241] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand this application, and the content of this specification should not be construed as a limitation of this application. Furthermore, for those skilled in the art, there will be different forms of changes in the specific implementation methods and application scope based on this application. It is neither necessary nor possible to exhaustively list all implementation methods here, and obvious changes or modifications derived therefrom are still within the protection scope of this application.

Claims

1. An ultraviolet photoelectron spectroscopy analyzer, characterized in that, include: The analysis chamber is equipped with a four-dimensional sample handling table for placing the sample to be tested. A monochromatic light generating system is sealed to the analysis chamber. The monochromatic light generating system is equipped with a beam splitter, which is used to split the incident light into reflected light and transmitted light. The transmitted light propagates along the main optical path into the analysis chamber and illuminates the surface of the sample to be tested, while the reflected light propagates along the reference optical path. A main optical path ultraviolet detector is installed in the analysis chamber to detect the number of photons in the main optical path; A reference optical path ultraviolet detector is disposed on the reference optical path for detecting the number of photons in the reference optical path; A channel electron multiplier, located in the analysis chamber, is used to detect the number of photoelectrons in the main optical path; A hemispherical energy analyzer, sealed to the analysis chamber, includes a multi-stage incident lens and a hemispherical deflector. The multi-stage incident lens is disposed at the incident end of the hemispherical deflector and faces the four-dimensional sample operating stage, for focusing incident photoelectrons. The inlet of the multi-stage incident lens is openable and closable. The multi-stage incident lens includes multiple cylindrical electron lenses, which are connected in series along the axial direction. The multi-stage incident lens has a variable diameter structure. The hemispherical deflector is used to filter photoelectrons with different kinetic energies. A two-dimensional electron imaging detector is connected to the output end of the hemispherical deflector to detect the momentum and energy information of the emitted photoelectrons.

2. The ultraviolet photoelectron spectroscopy analyzer according to claim 1, characterized in that: The ultraviolet photoelectron spectroscopy analyzer includes a first test mode and a second test mode. The first test mode is an ultraviolet photoelectron yield spectroscopy test mode, and the second test mode is an ultraviolet photoelectron energy spectroscopy test mode. In the first test mode, only the channel electron multiplier is operational, and the entrance to the multi-stage incident lens is closed; In the second test mode, only the hemispherical energy analyzer and the two-dimensional electron imaging detector are operational, and the entrance of the multi-stage incident lens is open.

3. The ultraviolet photoelectron spectroscopy analyzer according to claim 2, characterized in that: The hemispherical energy analyzer is located at the upper end of the analysis chamber, and the multi-stage incident lens is arranged vertically directly above the four-dimensional sample operation stage. The multi-stage incident lens is provided with a fully automatic aperture on the side near the four-dimensional sample operation stage. The fully automatic aperture is used to control the entrance of the multi-stage incident lens to be closed in the first test mode or opened in the second test mode.

4. The ultraviolet photoelectron spectroscopy analyzer according to claim 1, characterized in that: The multi-stage incident lens is a five-element incident lens, which includes a variable diameter region located at both ends of the five-element incident lens; in the variable diameter region, the radius of the electronic lens gradually decreases from the middle to the end of the five-element incident lens.

5. The ultraviolet photoelectron spectroscopy analyzer according to claim 1, characterized in that: The two-dimensional electron imaging detector includes a microchannel plate assembly, a fluorescent screen, and an industrial camera; The microchannel plate assembly includes a first microchannel plate and a second microchannel plate stacked sequentially, with the electron emission surface of the first microchannel plate and the electron incident surface of the second microchannel plate facing each other. The microchannel plate assembly is used to amplify photoelectrons. The fluorescent screen is disposed on the electron emission surface side of the second microchannel plate and is used to receive electron impacts and generate fluorescent images. The industrial camera is mounted close to the side of the fluorescent screen away from the second microchannel plate, and is used to acquire images on the fluorescent screen.

6. The ultraviolet photoelectron spectroscopy analyzer according to claim 5, characterized in that: The channel axes of the first microchannel plate and the second microchannel plate are at an angle of 5° to 15° to the normal direction of the microchannel plate assembly, respectively.

7. The ultraviolet photoelectron spectroscopy analyzer according to claim 1, characterized in that: The focusing electrode of the channel electron multiplier is oriented toward the four-dimensional sample stage and forms a 30° angle with the horizontal plane.

8. The ultraviolet photoelectron spectroscopy analyzer according to claim 1, characterized in that: The ultraviolet detector of the reference optical path includes a photodiode and a photomultiplier tube. The photodiode is used to detect photons in the reference optical path under a first light intensity condition, and the photomultiplier tube is used to detect photons in the reference optical path under a second light intensity condition. The first light intensity condition is that at an incident wavelength of 160 nm, the number of photons is ≤7×10. 8 The second light intensity condition is that at an incident wavelength of 160 nm, the number of photons is >7 × 10⁻⁶. 8 .

9. The ultraviolet photoelectron spectroscopy analyzer according to claim 8, characterized in that: The photodiode is movably disposed between the beam splitter and the photomultiplier tube. The photodiode is connected to a driving mechanism, which drives the photodiode to rotate or move so that the position of the photodiode is on or off the reference optical path.

10. A method for in-situ coupled analysis of ultraviolet photoelectron yield spectroscopy and energy dispersive spectroscopy, characterized in that, When applied to an ultraviolet photoelectron spectroscopy analyzer as described in any one of claims 1 to 9, the method includes the following steps: Under the same vacuum environment and without moving the spatial position of the sample under test, the first test mode and the second test mode are executed respectively. The first test mode is the ultraviolet photoelectron yield spectrum test mode: a monochromatic ultraviolet light with a continuously tunable wavelength is generated by a monochromatic light generation system and irradiated onto the surface of the sample to be tested; the intensity of the incident light is monitored by an ultraviolet detector in the reference optical path; the entrance of the multi-stage incident lens is closed; and the number of photoelectrons emitted by the sample at different wavelengths is detected by a channel electron multiplier to generate an ultraviolet photoelectron yield spectrum. The second test mode is the ultraviolet photoelectron spectroscopy test mode: monochromatic ultraviolet light of a fixed wavelength is generated by the monochromatic light generation system and irradiated onto the surface of the sample to be tested; the entrance of the multi-stage incident lens is opened; the energy and momentum distribution of the emitted photoelectrons are detected by the hemispherical energy analyzer and the two-dimensional electron imaging detector to generate an ultraviolet photoelectron spectrum; Based on the test results of the first test mode and the second test mode, the electronic structure physical parameters of the sample under test are cross-validated.

11. The method according to claim 10, characterized in that, The method includes: The photoelectron yield of the sample under test is measured at multiple different wavelengths to obtain the photoelectron yield spectrum of the sample under test. The multiple different wavelengths belong to the vacuum ultraviolet band. The horizontal axis of the photoelectron yield spectrum is the photon energy corresponding to the wavelength point, and the vertical axis is the photoelectron yield. At the target wavelength point, the momentum and energy information of the photoelectrons emitted by the sample under test are measured to obtain the ultraviolet photoelectron spectrum of the sample under test. The target wavelength point belongs to the vacuum ultraviolet band. The horizontal axis of the ultraviolet photoelectron spectrum is the binding energy, and the vertical axis is the photoelectron intensity. The ionization potential of the sample to be tested is determined based on the photoelectron yield spectrum, and the work function of the sample to be tested is determined based on the ultraviolet photoelectron energy spectrum. Subtracting the ionization potential from the work function yields the valence band top HOMO level of the sample under test.

12. The method according to claim 11, characterized in that, The photoelectron yield of the sample under test is measured at multiple different wavelengths to obtain the photoelectron yield spectrum of the sample under test, including: The monochromatic light in the vacuum ultraviolet band is split into a main transmission path and a reference reflection path at multiple different wavelengths. The number of incident photons in the reference optical path at each wavelength point is measured, and the number of incident photons in the main optical path at each wavelength point is also measured. The splitting ratio at each wavelength point is calculated based on the number of incident photons in the main optical path and the number of incident photons in the reference optical path at each wavelength point. The number of photoelectrons excited by the main optical path on the surface of the sample under test at each wavelength point is measured. The photoelectron yield spectrum of the sample under test is determined based on the splitting ratio at each wavelength point, the number of incident photons in the reference optical path, and the number of photoelectrons.

13. The method according to claim 12, characterized in that, The photoelectron yield spectrum of the sample under test is determined based on the splitting ratio at each wavelength, the number of incident photons in the reference optical path, and the number of photoelectrons, including: Based on the splitting ratio at each wavelength point, the number of incident photons in the main optical path at the corresponding wavelength point is corrected to obtain the actual number of incident photons in the main optical path at each wavelength point. Divide the number of photoelectrons at each wavelength point by the actual number of incident photons at the corresponding wavelength point to obtain the photoelectron yield value at each wavelength point. The photoelectron yield spectrum of the sample under test is obtained based on the photoelectron yield values ​​at the multiple different wavelength points.

14. The method according to claim 11, characterized in that, Determining the ionization potential of the sample to be tested based on the photoelectron yield spectrum includes: Based on the material type of the sample to be tested, select the corresponding power function model; Based on the power function model, a polynomial fitting calculation is performed on the starting region of the rising edge of the photoelectron yield spectrum to obtain the fitting curve. The ionization potential of the sample to be tested is determined based on the photoelectron yield spectrum and the fitted curve.

15. The method according to claim 14, characterized in that, The ionization potential of the sample to be tested is determined based on the photoelectron yield spectrum and the fitted curve, including: From the ultraviolet photoelectron yield spectrum, a horizontal baseline with a photoelectron yield value of zero is determined through data processing; Based on a preset power function model related to the material type of the sample to be tested, the rising edge starting region of the ultraviolet photoelectron yield spectrum is fitted to obtain a fitting curve. The fitted curve is extended towards the direction of low photon energy, and its intersection with the horizontal baseline is calculated. The photon energy value corresponding to the intersection is determined as the ionization potential of the sample to be tested.

16. The method according to claim 14, characterized in that, Based on the material type of the sample to be tested, a corresponding power function model is selected, including: Based on the material type of the sample to be tested, determine the excitation type and scattering type of the sample to be tested; Based on the excitation type and scattering type of the sample to be tested, a corresponding exponent value is defined for the power function model; Based on the power function model, a polynomial fitting calculation is performed on the starting region of the rising edge of the photoelectron yield spectrum to obtain the fitting curve, including: A nonlinear least squares fitting algorithm is used to fit the photon energy and photoelectron emission yield of the data points in the starting region to a polynomial function based on the exponent value defined by the power function model, thereby obtaining the fitting curve.

17. The method according to claim 11, characterized in that, At the target wavelength, the photoelectron momentum and energy information emitted by the sample under test are measured to obtain the ultraviolet photoelectron spectrum of the sample under test, including: The sample to be tested is irradiated with a photon beam of the target wavelength to obtain photoelectrons with different kinetic energies excited by the sample to be tested. Using a hemispherical energy analyzer, photoelectrons with different kinetic energies are screened from the photoelectrons with different kinetic energies excited by the sample under test. The signals of photoelectrons with different kinetic energies are amplified by a microchannel plate, and the corresponding light emission images are obtained on a fluorescent screen. The light emission images include pixels at multiple different positions. The luminescent images are captured in segments according to the photoelectron kinetic energy using an industrial camera. All the light-emitting images captured by the industrial camera are superimposed, and the pixels with the same electron kinetic energy are integrated to obtain the ultraviolet photoelectron spectrum of the sample under test.

18. The method according to claim 11, characterized in that, The work function of the sample to be tested is determined based on the ultraviolet photoelectron spectrum, including: The energy value of the secondary electron cutoff edge was determined from the ultraviolet photoelectron spectrum. The work function of the sample under test is calculated based on the photon energy corresponding to the target wavelength point and the secondary electron cutoff edge energy value.

19. The method according to claim 18, characterized in that, The secondary electron cutoff edge energy value is determined from the ultraviolet photoelectron spectrum, including: A digital filtering algorithm is used to process the ultraviolet photoelectron spectrum to obtain the noise-reduced ultraviolet photoelectron spectrum and the noise intensity level line. From the denoised ultraviolet photoelectron spectrum, a linear variation region containing the secondary electron cutoff edge was determined; The least squares method is used to linearly fit the relationship between photon intensity and photoelectron kinetic energy in the linearly changing region, and a fitted straight line is obtained. The intersection point of the fitted straight line and the noise intensity horizontal line is determined, and the photoelectron kinetic energy corresponding to the intersection point is determined as the secondary electron cutoff edge energy value.

20. The method according to claim 19, characterized in that, From the denoised ultraviolet photoelectron spectrum, a linear variation region containing the secondary electron cutoff edge was determined, including: Calculate the first derivative of the denoised ultraviolet photoelectron spectrum to obtain the derivative curve; From the derivative curve, the point on the horizontal axis corresponding to the photoelectron kinetic energy where the absolute value of the derivative first exceeds a preset threshold is determined as the starting point; Using the starting point as a reference, a predetermined energy width range is extended to the side with low photoelectron kinetic energy to obtain the linear variation region.

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