Optical system for an atomic force microscope

Abstract

The utility model relates to atomic force microscope field especially is involved in an optical system of adapting atomic force microscope, including light excitation module, optical path module, light excitation module is used to produce exciting light, and the wavelength of exciting light produced by light excitation module is adjustable, optical path module is used to transmit and inject exciting light produced by light excitation module to the surface of the sample to be measured, and the photoelectric response is produced based on the irradiation of exciting light of the sample to be measured, the photovoltage of the sample to be measured under the irradiation of the exciting light is detected through atomic force microscope to realize photoelectricity characteristic detection to the sample to be measured, the scheme can be adjusted light source wavelength flexibly to different samples, and the interface is left simultaneously and can be coupled laser, and it is not necessary to repeatedly arrange light source and optical path, and the convenience of detection is improved.

Description

Technical Field

[0001] This application relates to the field of atomic force microscopy, and in particular to an optical system adapted to atomic force microscopy. Background Technology

[0002] Existing atomic force microscopy (AFM) systems typically require customized designs for different light sources and optical paths when performing external light source tests. For example, different materials have different spectral response ranges (e.g., silicon's 1100nm infrared response, quantum dots' visible light response, TiO2's ultraviolet response, etc., requiring matching light sources of different wavelengths). Furthermore, because the scanning probe of the AFM system is very close to the sample (nanometer-scale) during scanning, the space left for the incident light path of the external light source is very small, making it difficult to adjust the optical path and resulting in poor performance. At the same time, this system can only test the changes in the surface voltage channel signal of the sample before and after illumination (the voltage of the sample after illumination is usually called "photovoltage"), and cannot characterize the changes in the voltage signal of the sample at different wavelengths. Utility Model Content

[0003] To address the problem that current atomic force microscope (AFM) systems require customized design of light sources and optical paths of different wavelengths for external light source testing, resulting in cumbersome operation and unchanging debugging, this application provides an optical system adapted to atomic force microscopes.

[0004] This application provides an optical system adapted to an atomic force microscope, including an optical excitation module and an optical path module;

[0005] The optical excitation module is used to generate excitation light; the wavelength of the excitation light generated by the optical excitation module is adjustable.

[0006] The optical path module is used to transmit the excitation light generated by the photoexcitation module and incident it onto the surface of the sample to be tested; the sample to be tested generates a photoelectric response based on the irradiation of the excitation light; the photovoltage of the sample to be tested under the irradiation of the excitation light is detected by an atomic force microscope, so as to realize the detection of the photoelectric properties of the sample to be tested.

[0007] By adopting the above technical solution, the wavelength of the light source can be flexibly adjusted for different samples, eliminating the need to repeatedly arrange the light source and optical path, thus improving the convenience of detection.

[0008] Optionally, the light excitation module includes a light source component, a beam splitting component, a wavelength filtering component, and a focusing component; the light source component is used to generate a broadband light source, the beam splitting component is arranged in the light output direction of the broadband light source to decompose the broadband light source into monochromatic light of different wavelengths; the wavelength filtering component is used to filter out monochromatic light of the target wavelength, and the excitation light is output after being focused by the focusing component.

[0009] By adopting the above technical solution, adaptive adjustment of monochromatic light of different wavelengths can be achieved according to testing requirements.

[0010] Optionally, the target wavelength is 300nm to 800nm.

[0011] By adopting the above technical solution, the adjustment range is 300nm-800nm, which can better meet the actual testing requirements.

[0012] Optionally, the light source assembly includes a xenon lamp capable of producing light in the 200nm to 1000nm wavelength range.

[0013] By adopting the above technical solutions, xenon lamps, as a broadband light source, can cover a wide range of light source wavelength requirements.

[0014] Optionally, the optical path module includes an optical fiber and an optical path reflection structure. The excitation light is transmitted to the optical path reflection structure through the optical fiber, and the optical path direction is adjusted by the optical path reflection structure to incident the excitation light onto the surface of the sample from above.

[0015] By adopting the above technical solution, the direction of the optical path can be adjusted through the optical path reflection structure, which can effectively avoid the interference of the original scanning probe and other components of the atomic force microscope.

[0016] Optionally, the optical fiber is adapted to wavelengths ranging from 250nm to 1000nm.

[0017] Optionally, the optical path module further includes a focusing lens disposed on the reflected light path of the optical path reflection structure, so as to focus the reflected light path to form a light spot that is incident on the surface of the sample to be tested.

[0018] Optionally, the optical path module further includes a coupler disposed on the optical fiber, the coupler having a reserved SMA type interface; the light source assembly further includes a laser light source, the laser light source being connected to the coupler through the SMA type interface.

[0019] By adopting the above technical solution, the scalability of the system is greatly enhanced, and an external laser interface is reserved for some test samples that cannot be excited by xenon lamp light source to generate photoelectric response.

[0020] Optionally, the optical system further includes a control module connected to the atomic force microscope and the photoexcitation module for performing photovoltage scanning on the sample to be tested.

[0021] By adopting the above technical solution, the control module can be used to scan the surface voltage spectrum within the target range, that is, to plot a curve for a certain point of the sample under test with the light source wavelength as the abscissa and the surface photovoltage as the ordinate.

[0022] In summary, this application includes at least the following beneficial technical effects:

[0023] 1. The wavelength of the light source can be flexibly adjusted for different samples, eliminating the need to repeatedly arrange the light source and optical path, thus improving the convenience of detection. Attached Figure Description

[0024] Figure 1 A schematic diagram of an optical system structure adapted for an atomic force microscope provided in this application embodiment. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the structure of a photoexcitation module provided in an embodiment of this application;

[0026] Figure 3 A schematic diagram of an optical system structure adapted for an atomic force microscope provided in this application embodiment. Figure 2 ;

[0027] Figure 4 A schematic diagram of an optical system structure adapted for an atomic force microscope provided in this application embodiment. Figure 3 ;

[0028] Figure 5 A schematic diagram of an optical system structure adapted for an atomic force microscope provided in this application embodiment. Figure 4 ;

[0029] Figure 6 A schematic diagram of an optical system structure adapted for an atomic force microscope provided in this application embodiment. Figure 5 ;

[0030] Figure 7 In-situ two-dimensional and three-dimensional morphological images of the sample to be tested provided in the embodiments of this application;

[0031] Figure 8 The voltage diagram of the sample to be tested before light is applied, provided in the embodiments of this application;

[0032] Figure 9 This is a voltage diagram of the sample under test after light is applied, provided in an embodiment of this application.

[0033] Figure 10 The surface voltage image of the sample after light application and before light application is provided in the embodiments of this application;

[0034] Figure 11 The photovoltage spectrum of the sample provided in the embodiments of this application is shown in the range of 300 nm to 800 nm. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0036] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to and includes any or all possible combinations of one or more of the listed items. The term “exemplary” means “serving as an example, embodiment, or illustration,” and any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. The terms “first” and “second” are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as “first” or “second” may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, “a plurality” means two or more.

[0037] In atomic force microscopy (AFM), a tiny cantilever is used to detect the interaction between the probe tip and the sample. The force causes the cantilever to oscillate. A laser beam illuminates the end of the cantilever; as the cantilever oscillates, the position of the reflected light changes, causing a displacement. The laser detector records this displacement and transmits the signal to the feedback system. This allows the system to make appropriate adjustments (for example, the feedback system uses the signal from the laser detector as a feedback signal, which serves as an internal adjustment signal to drive the scanner, typically made of a piezoelectric ceramic tube, to move appropriately to maintain a constant force between the sample and the probe tip). Generally, three symbols represent X, ... Piezoelectric ceramic blocks in the Y and Z directions form a tripod shape. The probe is driven to scan the sample surface by controlling the extension and retraction of the X and Y directions. The distance between the probe and the sample is maintained at the nanometer level by controlling the extension and retraction of the piezoelectric ceramics in the Z direction. Finally, the three-dimensional surface characteristics of the sample are presented as an image. In the surface potential mode of atomic force microscopy (i.e., Kelvin probe force microscopy, KPFM), a conductive atomic force probe is used to detect the interaction between the tip and the sample. The probe vibrates under the influence of an electric field. By adjusting the compensating DC current between the probe and the sample, the vibration of the probe is minimized (in this state, the voltage on the tip and the sample is the same). Because different regions of the sample surface have different work functions or surface potential states, these different regions will show potential contrast in the surface potential image.

[0038] Currently, when testing external light sources, atomic force microscopy systems typically require customized designs of different light sources and optical paths for different samples. Furthermore, because the scanning probe is very close to the sample (nanometer level) during scanning, the space left for the incident light path of the external light source is very small, making it difficult to adjust the optical path and resulting in poor performance.

[0039] To meet the different requirements of light source wavelength for different samples during in-situ testing with an atomic force microscope, avoid repeated light source and optical path setup, and solve the problem of poor debugging effect when temporarily setting up an optical path system on the atomic force microscope system, this application provides an optical system adapted to an atomic force microscope.

[0040] refer to Figure 1 The optical system includes a light excitation module 10 and an optical path module 20.

[0041] The optical excitation module 10 is used to generate excitation light; the wavelength of the excitation light generated by the optical excitation module 10 is adjustable.

[0042] The optical path module 20 is used to transmit the excitation light generated by the photoexcitation module 10 and incident it onto the surface of the sample 30 to be tested; the sample 30 to be tested generates a photoelectric response based on the irradiation of the excitation light; the photovoltage of the sample 30 to be tested under the irradiation of the excitation light is detected by the atomic force microscope 40, so as to realize the photoelectric characteristic detection of the sample 30 to be tested.

[0043] refer to Figure 2 In an optional embodiment of this application, the light excitation module 10 includes a light source component 11, a beam splitting component 12, a wavelength filtering component 13, and a focusing component 14; wherein the light source component 11 is used to generate a broadband light source, the beam splitting component 12 is arranged in the light output direction of the broadband light source to decompose the broadband light source into monochromatic light of different wavelengths; the wavelength filtering component 13 is used to filter out monochromatic light of the target wavelength, and the monochromatic light is focused by the focusing component 14 and then output as excitation light.

[0044] In an optional embodiment of this application, the target wavelength is 300nm to 800nm.

[0045] refer to Figure 3 In an optional embodiment of this application, the light source assembly 11 includes a xenon lamp 111, which can generate light in the 200nm to 1000nm wavelength band.

[0046] In optional embodiments of this application, a collimating optical element, such as a quartz lens (suitable for the ultraviolet to visible band, such as a f=50mm plano-convex lens) or a reflective collimating mirror (to avoid chromatic aberration, such as a parabolic mirror), can be provided between the light source assembly 11 and the beam splitting assembly 12 to convert the divergent light emitted by the light source into parallel light, which facilitates subsequent dispersion beam splitting.

[0047] The spectrometer 12 can be a planar diffraction grating, which uses periodically arranged lines (or grooves) to diffract light of different wavelengths in different directions, thereby achieving spectral separation.

[0048] The wavelength selection component 13 can be a broadband filter with a center wavelength of 550nm and a passband of 300-800nm. Alternatively, a slit can be used to achieve target wavelength selection. This embodiment does not limit the specific device used, as long as it can achieve target wavelength selection.

[0049] The focusing component 14 may be a focusing lens, such as a quartz lens.

[0050] In an optional embodiment of this application, a combination of a xenon lamp and a monochromator can also be used, with the monochromator grating controlled by a computer to achieve continuous wavelength output from 300nm to 800nm ​​(resolution ≤5nm).

[0051] Continue to refer to Figure 3The optical path module 20 includes an optical fiber 21 and an optical path reflection structure 22. Excitation light is transmitted through the optical fiber 21 to the optical path reflection structure 22. The optical path direction is adjusted by the optical path reflection structure 22 to direct the excitation light from above the sample 30 to the surface of the sample. The sample 30 is placed on the sample stage 50.

[0052] In an optional embodiment of this application, the wavelength range adapted to the optical fiber 21 is 250nm to 1000nm.

[0053] refer to Figure 4 In an optional embodiment of this application, the optical path module 20 further includes a focusing lens 23, which is disposed on the reflected light path of the optical path reflection structure 22, so as to focus the reflected light path to form a light spot that is incident on the surface of the sample 30 to be tested.

[0054] refer to Figure 5 In an optional embodiment of this application, the optical path module 20 further includes a coupler 24 disposed on the optical fiber 21, with an SMA (Sub-Miniature version A) interface reserved on the coupler 24; the light source assembly 11 further includes a laser light source 112, which is connected to the coupler 24 via an SMA interface. An external laser interface is reserved for samples under test that cannot be excited by the xenon lamp 111 light source, greatly enhancing the system's scalability.

[0055] refer to Figure 6 In an optional embodiment of this application, the optical system further includes a control module 60 connected to the atomic force microscope 40 and the photoexcitation module 10 for performing photovoltage scanning on the sample to be tested.

[0056] In an optional embodiment of this application, the control module 60 employs a photovoltage spectrometer. It should be understood that the core principle of a photovoltage spectrometer is based on the photovoltaic effect. When excitation light irradiates the sample material, photon energy is absorbed, exciting electron-hole pairs. Under the influence of an internal electric field or an applied electric field, electrons and holes separate and move directionally, forming a photovoltage. The photovoltage spectrometer obtains the photovoltage spectrum of the sample by scanning the wavelength of the excitation light and acquiring the photovoltage signal intensity at the corresponding wavelength. It should be noted that this embodiment is not limited to using a specific type of instrument, device, or optical component; any device capable of performing the corresponding function is acceptable.

[0057] This application combines photovoltage spectroscopy and atomic force microscopy techniques, utilizing the high resolution of atomic force microscopy scanning images to study the surface photovoltage properties of samples.

[0058] In an optional embodiment of this application, the Kelvin signal (photovoltage signal on the surface of the sample under test) from the atomic force microscope can be imported into the control module via a BNC data cable. Note that the atomic force microscope needs to be configured with the corresponding signal output settings, i.e., in the check parameter interface, set Output2 Data Type to Output and Output2Data to Drive2 DC Offset in the others section.

[0059] When operating this system, the first step should be to open it. Figure 5 The xenon lamp 111 is switched on (if a laser source is needed to excite the sample, the laser source 112 is also switched on). After the light path is split, filtered, and focused, it passes through the optical fiber 21 and coupler 24 to reach the light path reflection structure 22. After being shaped and focused by the focusing lens 23, a light spot is formed and hits the sample 30. At the same time, care should be taken to adjust the light path to avoid interference from the sample stage 50 and the scanning probe of the atomic force microscope 40. In addition, the Kelvin signal at the output2 interface of the General I / O of the original controller of the atomic force microscope 40 needs to be imported into the control module 60 for analysis via a BNC data cable. At this time, the photovoltage spectrometer control software can be opened, the target wavelength value can be set, and photovoltage image scanning can be performed; or the wavelength range can be set to the target wavelength range value to perform photovoltage spectral scanning. Note that the wavelength range can only be within 300nm-800nm.

[0060] In this embodiment, a 1cm long and wide sample of thin-film solar cell material is prepared as the test sample. First, the photovoltage of the test sample is measured. Figure 7 These are in-situ two-dimensional and three-dimensional morphology images of the sample to be tested. Figure 8 The voltage diagram of the sample before light is applied. Figure 9 The voltage diagram of the sample after light is applied. Figure 10 This image shows the surface voltage of the sample after illumination is applied, minus the voltage before illumination. This image reflects the distribution of photogenerated carriers. Figure 11 Photovoltage spectra of two thin-film solar cell samples prepared using different processes in the 300 nm to 800 nm range (samples are numbered 13# and 14#).

[0061] The above description of the embodiments is only used to provide a detailed introduction to the technical solutions of this application. However, the description of the above embodiments is only for the purpose of helping to understand the methods and core ideas of this application, and should not be construed as a limitation of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.

Claims

1. An optical system adapted for an atomic force microscope, characterized in that, Includes optical excitation module and optical path module; The optical excitation module is used to generate excitation light; the wavelength of the excitation light generated by the optical excitation module is adjustable. The optical path module is used to transmit the excitation light generated by the photoexcitation module and incident it onto the surface of the sample to be tested; the sample to be tested generates a photoelectric response based on the irradiation of the excitation light; The photovoltage of the sample under test under the excitation light is detected by atomic force microscopy to achieve the detection of the photoelectric properties of the sample.

2. The optical system as described in claim 1, characterized in that, The light excitation module includes a light source component, a beam splitting component, a wavelength filtering component, and a focusing component. The light source component is used to generate a broadband light source. The beam splitting component is positioned in the light emission direction of the broadband light source to decompose the broadband light source into monochromatic light of different wavelengths. The wavelength filtering component is used to filter out monochromatic light of the target wavelength, which is then focused by the focusing component and output as excitation light.

3. The optical system as described in claim 2, characterized in that, The target wavelength is 300nm to 800nm.

4. The optical system as described in claim 3, characterized in that, The light source assembly includes a xenon lamp, which can produce light in the 200nm to 1000nm wavelength range.

5. The optical system as described in claim 4, characterized in that, The optical path module includes an optical fiber and an optical path reflection structure. The excitation light is transmitted to the optical path reflection structure through the optical fiber. The optical path reflection structure is used to adjust the direction of the optical path so that the excitation light is incident on the surface of the sample from above the sample.

6. The optical system as claimed in claim 5, characterized in that, The optical fiber is adapted to wavelengths ranging from 250nm to 1000nm.

7. The optical system as claimed in claim 6, characterized in that, The optical path module also includes a focusing lens, which is disposed on the reflected light path of the optical path reflection structure to focus the reflected light path to form a light spot that is incident on the surface of the sample to be tested.

8. The optical system as claimed in claim 7, characterized in that, The optical path module also includes a coupler mounted on the optical fiber, with an SMA-type interface reserved on the coupler; the light source assembly also includes a laser light source, which is connected to the coupler through the SMA-type interface.

9. The optical system as claimed in claim 8, characterized in that, The optical system also includes a control module connected to the atomic force microscope and the photoexcitation module for performing photovoltage scanning on the sample under test.

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