Two-photon transient fluorescence microscopy for diagnosing high pressure carrier three-dimensional diffusion process

Abstract

The present application relates to a kind of diagnosis high voltage download carrier three-dimensional diffusion process two-photon transient fluorescence microscope, belong to the field of microscopic imaging.Pulse laser excitation and detection part and signal collection part are placed on the same optical platform, computer one in pulse laser excitation and detection part and computer two in detection signal collection part are placed outside optical platform.Advantages are that wavelength tunable femtosecond laser, dichroic mirror and long working distance high-power microscope objective are used to pump excitation to the sample under the pressure applied in diamond anvil, ensure two-photon excitation of carrier in semiconductor under high pressure, improve the imaging depth of carrier;Using wavelength 780 nm femtosecond laser as detection light to detect carrier in sample, cooperate with laser scanning system, realize the spatial scanning of carrier by changing the scanning angle of scanning galvanometer, can obtain the diffusion law of carrier in time and space.

Description

Technical Field

[0001] This invention belongs to the field of microscopic imaging, specifically relating to a transient microscopic imaging system based on two-photon excited femtosecond transient emission technology, suitable for diagnosing the three-dimensional transport mechanism of charge carriers in semiconductors under high voltage conditions. Background Technology

[0002] Charge carriers, as a transient species in semiconductors, play a crucial role in various semiconductor-based electronic and optoelectronic devices. Detecting their diffusion process has always been an important research topic in semiconductor physics. To gain a competitive edge in the current information field, it is essential to enhance our understanding of charge carrier diffusion in semiconductor materials and to measure information such as diffusion rates. Visualizing the diffusion process of charge carriers will undoubtedly promote a deeper understanding of the diffusion mechanism. Utilizing the fundamental principle of charge carrier recombination luminescence, charge carriers are obtained in semiconductors through optical excitation, and the recombination luminescence dynamics of these photogenerated charge carriers at different spatial locations within the semiconductor can be detected. By comparing the differences in the recombination luminescence dynamics of photogenerated charge carriers at different locations, the diffusion length and diffusion rate of the charge carriers can be calculated using the carrier diffusion rate equation, thus achieving visualized detection of the spatial diffusion process of charge carriers.

[0003] Traditional transient emission spectroscopy, based on single-photon excitation to induce carrier generation, is primarily used to study the diffusion mechanism of carriers in semiconductor thin films in a two-dimensional spatial plane. However, due to the limited penetration depth of single-photons satisfying the transition rules, three-dimensional diffusion studies of carriers in semiconductors can only be conducted at finite depths, offering limited assistance in understanding the carrier diffusion mechanism. Furthermore, the spatial diffusion behavior of carriers is influenced by factors such as the crystal structure of the semiconductor material and phonon scattering, resulting in limited findings from studies conducted only at room temperature and pressure.

[0004] Therefore, current research on the three-dimensional diffusion behavior of charge carriers in semiconductors has reached a bottleneck, as the underlying physical mechanisms remain unclear or controversial. Pressure is a crucial parameter for regulating the properties of matter; it can alter the electronic energy states and crystal structure of semiconductors, and induce the formation of new high-pressure phases with novel properties, revealing many new phenomena and laws not observed under normal pressure. Thus, the introduction of high-pressure technology helps clarify or resolve unclear or controversial issues under normal pressure. To ensure spatial resolution close to the diffraction limit, high-magnification objectives are often used, limiting their working distance. To ensure the sample is under high pressure, diamond anvil cells are often used to apply pressure. This system has a certain thickness, and the working distance of conventional high-magnification objectives is relatively short, making it impossible to focus the beam into the microcavity of the diamond anvil cell to excite and probe the sample within. Summary of the Invention

[0005] This invention provides a two-photon transient fluorescence microscope for diagnosing the three-dimensional diffusion process of charge carriers under high pressure. It is a transient microscopic imaging system based on two-photon excited femtosecond transient emission technology, suitable for diagnosing the three-dimensional transport mechanism of charge carriers in semiconductors under high pressure conditions. By using femtosecond laser technology in conjunction with a laser scanning system, spectrometer, and CCD camera, the three-dimensional detection of charge carriers under high pressure conditions is realized, thereby obtaining the motion law of charge carriers.

[0006] The technical solution adopted in this invention is as follows: it consists of a pulsed laser excitation and detection section and a detection signal collection section, wherein the pulsed laser excitation and detection section and the signal collection section are placed on the same optical platform, and the computer in the pulsed laser excitation and detection section and the computer in the detection signal collection section are placed outside the optical platform; the signal input port a of the scanning galvanometer in the pulsed laser excitation and detection section is connected to the signal output port b of the computer, and the signal output port d of the CCD camera is connected to the signal input port c of the computer; the signal output port e of the spectrometer in the detection signal collection section is connected to the signal input port f of the computer, and the signal output port h of the CCD camera is connected to the signal input port g of the computer; the detection signal collection section is located to the left rear of the pulsed laser excitation and detection section.

[0007] The pulsed laser excitation and detection section of this invention includes a wavelength-tunable femtosecond laser, a dichroic mirror, a microscope objective, a high-voltage anvil, a 780nm pulsed laser, an 800nm ​​double-sided polished dielectric film total internal reflection mirror, a scanning galvanometer, a scanning lens, a 1:1 beam splitter, a CCD camera, a sleeve lens, and a computer. The scanning galvanometer, scanning lens, 1:1 beam splitter, sleeve lens, dichroic mirror, microscope objective, and high-voltage anvil are arranged from left to right on the same horizontal center line. The wavelength-tunable femtosecond laser and dichroic mirror are arranged sequentially from back to front. The 780nm pulsed laser is located to the right of the 800nm ​​double-sided polished dielectric film total internal reflection mirror, which is located behind the scanning galvanometer. The CCD camera is located behind the 1:1 beam splitter. The scanning galvanometer has a signal input port a, the CCD camera has a signal output port d, and the computer has a signal output port b and a signal input port c.

[0008] The microscope objective described in this invention is a 100x Olympus microscope objective.

[0009] This invention uses a computer to control the scanning angle of a scanning galvanometer, thereby tracking the diffusion of charge carriers in different directions.

[0010] The detection signal collection part of the present invention includes a spectrometer, an aperture, a second 1:1 beam splitter, a second CCD camera, and a focusing lens. The spectrometer, aperture, second 1:1 beam splitter, and focusing lens are arranged in order from back to front and are located on the same horizontal center line. The second 1:1 beam splitter and the second CCD camera are arranged in order from left to right and are located on the same horizontal center line. The spectrometer is provided with a signal output port e, the second CCD camera is provided with a signal output port h, and the second computer is provided with a signal input port f and a signal input port g.

[0011] The spectrometer described in this invention includes a photomultiplier tube.

[0012] The advantages of this invention are: First, it employs a wavelength-tunable femtosecond laser, LightConversion, a dichroic mirror, and a high-magnification microscope objective with a long working distance (100x Olympus microscope objective (SLMPLN100X)) to pump and excite samples under pressure in a diamond anvil cell, ensuring two-photon excitation of charge carriers in the semiconductor under high-pressure conditions and improving the imaging depth of the charge carriers; second, it utilizes a wavelength of 780 nm... A femtosecond laser at a wavelength of nm is used as the probe light to detect charge carriers in the sample. Combined with a laser scanning system consisting of a scanning galvanometer, scanning lens, sleeve lens, and microscope objective, spatial scanning of charge carriers is achieved by changing the scanning angle of the scanning galvanometer. Third, the use of a 1:1 beam splitter and a CCD camera ensures that the sample is placed at the focal point of the objective, thus minimizing the light spot on the sample. The use of a 1:1 beam splitter and a CCD camera allows observation of the position of the probe light on the sample, enabling visualization during the excitation and detection of charge carriers. Finally, the use of a spectrometer allows for the acquisition of the diffusion patterns of charge carriers in time and space, leading to a deeper understanding of the physical mechanisms of charge carrier diffusion behavior. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention;

[0014] Figure 2 This is a schematic diagram of the structure of the pulsed laser excitation and detection part I of the present invention;

[0015] Figure 3 This is a schematic diagram of the structure of the detection signal collection part II of the present invention. Detailed Implementation

[0016] like Figure 1As shown, it consists of a pulsed laser excitation and detection section I and a detection signal collection section II. The pulsed laser excitation and detection section I and the signal collection section II are placed on the same optical platform. Computer 12 in the pulsed laser excitation and detection section I and computer 29 in the detection signal collection section II are placed outside the optical platform. The signal input port a of the scanning galvanometer 7 in the pulsed laser excitation and detection section I is connected to the signal output port b of computer 12, and the signal output port d of the CCD camera 10 is connected to the signal input port c of computer 12. The signal output port e of the spectrometer 13 in the detection signal collection section II is connected to the signal input port f of computer 28, and the signal output port h of the CCD camera 216 is connected to the signal input port g of computer 29. The detection signal collection section II is located to the left rear of the pulsed laser excitation and detection section I.

[0017] like Figure 2 As shown, the pulsed laser excitation and detection section I includes a wavelength-tunable femtosecond laser (LightConversion) 1, a dichroic mirror 2, a microscope objective 3, a high-voltage anvil 4, a 780nm pulsed laser 5, an 800nm ​​double-sided polished dielectric film total reflection mirror 6, a scanning galvanometer 7, a scanning lens 8, a 1:1 beam splitter 9, a CCD camera 10, a sleeve lens 11, and a computer 12. The scanning galvanometer 7, scanning lens 8, 1:1 beam splitter 9, sleeve lens 11, dichroic mirror 2, microscope objective 3, and high-voltage anvil 4 are arranged from left to right and located on the same horizontal center line. The wavelength-tunable femtosecond laser 1 and the dichroic mirror 2 are arranged sequentially from back to front. The nm pulsed laser 5 is located to the right of the 800nm ​​double-sided polished dielectric film total reflection mirror 6, which is located behind the scanning galvanometer 7. The CCD camera 10 is located behind the 1:1 beam splitter 9. The scanning galvanometer 7 is equipped with a signal input port a, the CCD camera 10 is equipped with a signal output port d, and the computer 12 is equipped with a signal output port b and a signal input port c.

[0018] The microscope objective 3 described in this invention is a 100x Olympus microscope objective.

[0019] The present invention uses a computer-12 to control the scanning angle of the scanning mirror 7, thereby tracking the diffusion of charge carriers in different directions.

[0020] like Figure 3As shown, the detection signal collection section II includes a spectrometer 14, an aperture 15, a 1:1 beam splitter 16, a CCD camera 17, and a focusing lens 18. The spectrometer 14, aperture 15, 1:1 beam splitter 16, and focusing lens 18 are arranged in order from back to front and are located on the same horizontal center line. The 1:1 beam splitter 16 and CCD camera 17 are arranged in order from left to right and are located on the same horizontal center line. The spectrometer 14 is provided with a signal output port e, the CCD camera 17 is provided with a signal output port h, and the computer 18 is provided with a signal input port f and a signal input port g.

[0021] The spectrometer 14 of the present invention includes a photomultiplier tube 13.

[0022] Working principle:

[0023] A wavelength-tunable femtosecond laser (Light Conversion 1) outputs a high-energy femtosecond laser pulse, which, after reflection by a dichroic mirror 2, enters a high-magnification microscope objective 3 (100x Olympus microscope objective (SLMPLN100X)) with a long working distance to pump and excite the sample in the diamond anvil cell 4. The excited sample emits fluorescence, which is then passed through the microscope objective 3, dichroic mirror 2, sleeve lens 11, 1:1 beam splitter 9, scanning lens 8, scanning galvanometer 7, 800nm ​​double-sided polished dielectric film total reflection mirror 6, and focusing lens... The mirror 18, the 1:1 beam splitter 16, and the aperture 15 enter the spectrometer 14 (which includes a photomultiplier tube 13). The signal output port e of the spectrometer 14 is connected to the signal input port f of the computer 19 to form a spectral signal and obtain the diffusion information of the charge carriers. The fluorescence is split by the 1:1 beam splitter 9 and enters the CCD camera 10. The signal output port d of the CCD camera 10 is connected to the signal input port c of the computer 12, which allows observation of the light spot generated when the sample is excited, thereby determining the position of the sample excited by the excitation light.

[0024] A 780 nm laser 5 is used as the detection light. It passes through an 800 nm double-sided polished dielectric film total reflection mirror 6, a scanning galvanometer 7, a scanning lens 8, a 1:1 beam splitter 9, a sleeve lens 11, a dichroic mirror 2, a microscope objective 3, and a high-pressure anvil 4 to enter the sample for fluorescence signal detection. The signal input port a of the scanning galvanometer 7 is connected to the signal output port b of the computer 12. The computer 12 controls the scanning angle of the scanning galvanometer 7 to track the diffusion of charge carriers in different directions. During the detection of charge carriers, the fluorescence emitted by the sample is split by the 1:1 beam splitter 16 and enters the CCD camera 17. The signal output port h of the CCD camera 17 is connected to the signal input port g of the computer 19. The images of the sample detected by the detection light at different positions can be observed, thereby allowing for more precise adjustment of the scanning angle of the scanning galvanometer 7.

[0025] This invention enables visualized scanning and detection of charge carriers in three-dimensional space of samples under high pressure conditions, leading to a deeper understanding of the physical mechanism of charge carrier diffusion behavior.

[0026] The main technical performance indicators are as follows:

[0027] Spatial resolution <1 μm; pressure control range 0~20 GPa; pump laser wavelength range 800 nm; probe laser wavelength range 450~800 nm; fluorescence measurement range 450~750 nm; system dynamic measurement range 50 ns~1 μs; system temporal resolution <200 ps.

Claims

1. A two-photon transient fluorescence microscope for diagnosing the three-dimensional diffusion process of charge carriers under high voltage, characterized in that: It consists of a pulsed laser excitation and detection section and a detection signal collection section. The pulsed laser excitation and detection section includes a wavelength-tunable femtosecond laser, a dichroic mirror, a microscope objective, a high-voltage anvil, a 780nm pulsed laser, an 800nm ​​double-sided polished dielectric film total internal reflection mirror, a scanning galvanometer, a scanning lens, a 1:1 beam splitter, a CCD camera, a sleeve lens, and a computer. The scanning galvanometer, scanning lens, 1:1 beam splitter, sleeve lens, dichroic mirror, microscope objective, and high-voltage anvil are arranged from left to right and are located at the same horizontal level. Along the center line, a wavelength-tunable femtosecond laser and a dichroic mirror are arranged sequentially from back to front. A 780nm pulsed laser is located to the right of an 800nm ​​double-sided polished dielectric film total internal reflection mirror, which is located behind a scanning galvanometer. A CCD camera is located behind a 1:1 beam splitter. The scanning galvanometer has a signal input port a, the CCD camera has a signal output port d, and the computer has a signal output port b and a signal input port c. The detection signal collection section includes a spectrometer, an aperture, a second 1:1 beam splitter, and a CCD camera. The system comprises a CCD camera and a focusing lens. The spectrometer, aperture, 1:1 beam splitter II, and focusing lens are arranged sequentially from back to front and on the same horizontal center line. The 1:1 beam splitter II and CCD camera II are arranged sequentially from left to right and on the same horizontal center line. The spectrometer has a signal output port e, the CCD camera II has a signal output port h, and the computer II has signal input ports f and g. The pulsed laser excitation and detection section and the signal collection section are placed on the same optical platform. The computer I in the pulsed laser excitation and detection section and the computer II in the signal collection section are placed outside the optical platform. The scanning galvanometer signal input port a in the pulsed laser excitation and detection section is connected to the signal output port b of computer I, and the signal output port d of CCD camera I is connected to the signal input port c of computer I. The spectrometer signal output port e in the signal collection section is connected to the signal input port f of computer II, and the signal output port h of CCD camera II is connected to the signal input port g of computer II. The signal collection section is located to the left rear of the pulsed laser excitation and detection section. The femtosecond laser pulse output from a wavelength-tunable femtosecond laser is reflected by a dichroic mirror and enters the microscope objective. This pulse pumps and excites the sample in a high-pressure anvil. The excited sample emits fluorescence, which passes through the microscope objective, dichroic mirror, sleeve lens, 1:1 beam splitter I, scanning lens, scanning galvanometer, 800nm ​​double-sided polished dielectric film total internal reflection mirror, focusing lens, 1:1 beam splitter II, and aperture before entering the spectrometer. The spectrometer's signal output port e is connected to the signal input port f of computer II, forming a spectral signal and obtaining carrier diffusion information. The fluorescence is split by 1:1 beam splitter I and enters CCD camera I. The signal output of CCD camera I is connected to the signal input port c of computer I, allowing observation of the light spot generated when the sample is excited, thus determining the position of the sample excited by the excitation light. 780 The light beam emitted by the nm pulsed laser is used as the probe light. It passes through an 800nm ​​double-sided polished dielectric film total reflection mirror, a scanning galvanometer, a scanning lens, a 1:1 beam splitter, a sleeve lens, a dichroic mirror, a microscope objective, and a high-pressure anvil before entering the sample to detect the fluorescence signal. The signal input port a of the scanning galvanometer is connected to the signal output port b of computer one. Computer one controls the scanning angle of the scanning galvanometer to track the diffusion of charge carriers in different directions. During the detection of charge carriers, the fluorescence emitted by the sample is split by the 1:1 beam splitter and enters CCD camera two. The signal output port h of CCD camera two is connected to the signal input port g of computer two, allowing the observation of images of the sample detected by the probe light at different positions.

2. The two-photon transient fluorescence microscope for diagnosing the three-dimensional diffusion process of high-voltage charge carriers according to claim 1, characterized in that: The microscope objective used is a 100x Olympus microscope objective.

3. The two-photon transient fluorescence microscope for diagnosing the three-dimensional diffusion process of high-voltage charge carriers according to claim 1, characterized in that: The spectrometer includes a photomultiplier tube.

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