Method for detecting electronic point defects

Abstract

The application provides a kind of electronic point defect detection method, it is related to quantum technical field.The electronic point defect detection method includes: the wavelength of first ionizing light is changed in wavelength range and irradiates any sub-region of the multiple sub-regions of the solid to be measured, determines the ionization spectrum of the fluorescent probe point defect corresponding to the sub-region;In the case where the ionization spectrum determines that there is an electronic point defect in the sub-region, the following operations are iteratively performed until the modified ionization spectrum meets the preset condition, and the type of the electronic point defect in the sub-region is determined according to the ionization spectrum that meets the preset condition: the threshold wavelength is determined according to the ionization spectrum, the threshold wavelength represents the critical wavelength that ionizes all electronic point defects in the sub-region;The wavelength range, power and irradiation time of the first ionizing light are changed, and the sub-region is irradiated again using the changed first ionizing light to obtain a modified ionization spectrum;Wherein, the modified wavelength range is determined according to the threshold wavelength.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum technology, in particular to a method for detecting electronic point defects. BACKGROUND

[0002] In the development of various modern science and technology, the research on defects in the sample to be measured has an impact on the fields of material mechanical engineering, solar cells and semiconductor technology, etc. In emerging quantum information technology, some solid-state defects have become the basic building blocks of quantum computing, quantum networks and quantum sensing. Although optical methods are suitable for detecting fluorescent defects, a large number of charge state changes in the sample to be measured cannot be directly detected by optical methods because the intensity of the emitted fluorescence is weak, or it is beyond the range of the detector, etc.

[0003] The existing methods for detecting electronic point defects mainly include: using a transmission electron microscope (TEM) to detect electronic point defects, using a scanning probe microscope (SPM) to detect electronic point defects, and using secondary ion mass spectrometry (SIMS) to detect electronic point defects. The principle of using a transmission electron microscope (TEM) to detect electronic point defects is to use an electron beam to pass through a thin film sample and interact with atoms of the sample, which can image point defects in the thin film sample and nanoparticles, thereby realizing the detection of electronic point defects in the thin film sample. However, this method is not suitable for bulk samples. The method of using a scanning probe microscope (SPM) to detect electronic point defects includes: using the near-field interaction between the probe tip and the sample surface to provide a surface point defect image with atomic resolution, thereby realizing the detection of electronic point defects on the surface of the sample. This method is not suitable for detecting point defects inside a solid sample. The method of using secondary ion mass spectrometry can detect ppb level of heterogeneous electronic point defects, but it is destructive to the sample. SUMMARY

[0004] In view of the above problems, the present application provides a method for detecting electronic point defects.

[0005] According to an embodiment of the present application, the method for detecting electronic point defects comprises:

[0006] controlling the wavelength of the first ionizing light to vary in a wavelength range and irradiating any sub-region of a plurality of sub-regions of the sample to be measured, and determining an ionization spectrum of the fluorescent probe point defect corresponding to the sub-region; wherein the ionization spectrum represents the variation of the jump amplitude of the local electric field in which the fluorescent probe point defect is located after the fluorescent probe point defect is irradiated by the first ionizing light with the wavelength.

[0007] In the case that the electronic point defects in the sub-region are determined according to the ionization spectrum, the following operation is iteratively performed until the modified ionization spectrum meets a preset condition, and the type of the electronic point defects in the sub-region is determined according to the ionization spectrum meeting the preset condition; the preset condition is that the energy level information obtained according to the characteristic wavelength with a non-zero jump amplitude in the modified ionization spectrum is located in a preset energy level information set:

[0008] The threshold wavelength is determined according to the ionization spectrum, and the threshold wavelength represents a critical wavelength for ionizing all the electronic point defects in the sub-region.

[0009] The wavelength range, power and irradiation time length of the first ionization light are modified, and the sub-region is irradiated again by using the modified first ionization light to obtain a modified ionization spectrum; wherein the modified wavelength range is determined according to the threshold wavelength.

[0010] According to the embodiment of the present application, the modified wavelength range is determined according to the threshold wavelength, which includes:

[0011] The minimum wavelength of the modified wavelength range is the threshold wavelength.

[0012] According to the embodiment of the present application, after the threshold wavelength is obtained, the detection method further includes:

[0013] The sub-region is irradiated by using the second ionization light to determine a power spectrum of the fluorescent probe point defects corresponding to the sub-region; wherein the power spectrum represents the change of the jump amplitude of the local electric field of the fluorescent probe point defects with the power after the sub-region is irradiated by the second ionization light; wherein the wavelength of the second ionization light is the threshold wavelength.

[0014] The threshold power is obtained according to the power spectrum, and the threshold power represents a critical power for ionizing all the electronic point defects in the sub-region.

[0015] According to the embodiment of the present application, after the threshold wavelength is obtained, the detection method further includes:

[0016] The sub-region is irradiated by using the third ionization light to determine a time spectrum of the fluorescent probe point defects corresponding to the sub-region; the time spectrum represents the change of the jump amplitude of the local electric field of the fluorescent probe point defects with the irradiation time length after the sub-region is irradiated by the third ionization light; wherein the wavelength of the third ionization light is the threshold wavelength.

[0017] The threshold time length is obtained according to the time spectrum, and the threshold time length represents a critical time length for ionizing all the electronic point defects in the sub-region.

[0018] According to the embodiment of the present application, the power and the irradiation time length of the first ionization light are modified, which includes:

[0019] The power of the first ionization light is modified to the threshold power, and the irradiation time length of the first ionization light is modified to the threshold time length.

[0020] According to an embodiment of the present application, determining the existence of the electron point defect in the sub-region according to the ionization spectrum includes:

[0021] In the case that the jump amplitude of the local electric field of the fluorescent probe point defect in the ionization spectrum is not 0, the existence of the electron point defect in the sub-region is determined.

[0022] According to an embodiment of the present application, determining the type of the electron point defect of the sub-region according to the ionization spectrum satisfying the preset condition includes:

[0023] According to the energy level information obtained from the characteristic wavelength in the ionization spectrum satisfying the preset condition and the mapping relationship between the energy level information and the type of the electron point defect, the type of the electron point defect is determined.

[0024] According to an embodiment of the present application, in the case that the number of the electron point defect of the sub-region is 1 according to the time spectrum or the power spectrum, determining the threshold wavelength according to the ionization spectrum includes:

[0025] Determining a plurality of ionization spectra of the fluorescent probe point defect corresponding to the sub-region;

[0026] For any wavelength in the first range, the jump amplitude of any wavelength in the plurality of ionization spectra is obtained;

[0027] According to the jump amplitude of any wavelength in the plurality of ionization spectra, the jump probability of the fluorescent probe point defect at any wavelength is obtained;

[0028] According to the jump probability of all wavelengths in the first range, a jump probability spectrum is obtained;

[0029] The threshold wavelength is determined according to the jump probability spectrum.

[0030] According to an embodiment of the present application, for a target sub-region in which the electron point defect exists and the number of the electron point defect is not 1, after determining the type of the electron point defect of the target sub-region, the detection method further includes:

[0031] Irradiating the target sub-region with fourth ionizing light to obtain the total jump amplitude of the local electric field of the fluorescent probe point defect corresponding to the target sub-region after being irradiated by the fourth ionizing light; the wavelength of the fourth ionizing light is a wavelength at which single-photon ionization of any target type of electron point defect in the target sub-region occurs;

[0032] Obtaining the unit jump amplitude of the fluorescent probe point defect corresponding to the target sub-region when a single electron point defect of the target type is located at the center position of the target sub-region;

[0033] According to the total jump amplitude and the unit jump amplitude, the number and concentration of the electron point defect of the target type of the target sub-region are determined.

[0034] According to an embodiment of the present application, the sample to be measured is a wide band gap semiconductor material.

[0035] According to an embodiment of the present application, the threshold wavelength iterative optimization mechanism based on the ionization spectrum can provide the critical conditions for ionizing the electron point defects in the focused sub-region by gradually narrowing the first ionization light wavelength range and constantly matching the power and illumination time of the first ionization light, so as to avoid irrelevant wavelength and parameter interference and make the energy level information detection more targeted.

[0036] According to an embodiment of the present application, the iterative optimization process can not only determine the ionization spectrum that meets the preset condition, but also determine the energy level characteristics of the electron point defects through multiple parameter adjustments, so as to avoid missing key information due to single iteration and ensure the accuracy of the detected types of electron point defects.

[0037] The detection method provided in the embodiments of the present application uses the fluorescent probe point defects inside the sample to be measured as a signal medium to realize the detection of the electron point defects, and does not need to rely on the interaction between the probe and the sample to be measured, so the detection method provided in the embodiments of the present application can not only detect the electron point defects on the surface of the sample but also detect the electron point defects inside the sample.

[0038] The embodiments of the present application use the first ionization light to irradiate any sub-region of the sample to be measured, and realize the detection of the electron point defects through the local electric field detection of the fluorescent probe point defects, without the need for filmization cutting and other processing of the solid sample, so that the detection of the electron point defects of the block solid can be directly realized. The embodiments of the present application only rely on the electric field response of the fluorescent probe point defects themselves to complete signal acquisition, and the physical structure of the solid sample is not changed throughout the process, so the method provided in the embodiments of the present application is non-destructive to the solid sample. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and other objects, features and advantages of the present application will become more apparent from the following description of the present application taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 A flowchart of the detection method of the electron point defects provided in the embodiments of the present application is shown.

[0041] Figure 2 A schematic diagram of the spot depth energy distribution of the first ionization light obtained by simulation is shown.

[0042] Figure 3 A schematic diagram of a plurality of sub-regions included in the region to be measured is shown.

[0043] Figure 4 An energy level structure of a point defect provided in the embodiments of the present application is shown.

[0044] Figure 5 The relative position relationship between any sub-region and corresponding fluorescent probe point defect provided by the embodiment of the present application is shown.

[0045] Figure 6 The energy level diagram of various electronic point defects that the sub-region can include is shown.

[0046] Figure 7 The schematic diagram of the detection device provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0047] In the process of implementing the present application, it is found that the traditional characterization method of electronic point defects has significant limitations in detection applicability and targeting. The core of the characterization method of photoluminescence spectroscopy (PLS) relies on the fluorescence emission of the electronic point defect to be measured, and the energy level information is obtained by directly collecting the defect light emission signal, so it can only characterize defects with fluorescence emission capability. For electronic point defects without fluorescence or with weak fluorescence signal (such as charge state transition without photon radiation), effective detection cannot be achieved. The characterization method of photoluminescence excitation spectroscopy (PLES) follows the same core logic as photoluminescence spectroscopy, which requires that the electronic point defect to be measured can emit detectable fluorescence: by scanning the excitation light wavelength and monitoring the defect fluorescence intensity change to deduce the energy level characteristics, it also cannot cover electronic point defects without fluorescence response, and the detection range is limited to the optical emission characteristics of electronic point defects. The characterization method of deep level transient spectroscopy (DLTS) is mainly used for analyzing the electrical characteristics of defects in wide-band semiconductors, which relies on the macroscopic capacitance change signal generated after a large number of electronic point defects to be measured are ionized. This method not only has strict requirements for the concentration of electronic point defects (a sufficient number of electronic point defects are required to form a detectable capacitance response), but also has an energy level limitation in the detection range (only electronic point defects with an energy level less than 1 electron volt can be effectively characterized), and an additional capacitance measurement system needs to be built, which cannot realize the targeted detection of low-concentration and wide-energy-level-range defects. Based on the above problems, the embodiment of the present application provides a more universal, high-sensitivity and wide-energy-level-range electronic point defect detection method. In order to make the purpose, technical scheme and advantages of the present application more clear and apparent, the following will combine specific embodiments and refer to the drawings to further describe the present application in detail.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the terms "comprises", "comprising", "includes", "including" and the like are specifically intended to be open-ended terms meaning that other elements can be added.

[0049] All terms used herein including technical and scientific terms have the meanings commonly understood by one of ordinary skill in the art unless otherwise specified. It should be noted that the terms used herein are defined as having meanings consistent with the context of the specification, and should not be interpreted in an idealized or overly formal sense.

[0050] Figure 1 A flowchart of a method for detecting an electronic point defect is shown according to an embodiment of the application.

[0051] As shown in Figure 1 The method for detecting an electronic point defect includes operations S1-S4.

[0052] In operation S1, the wavelength of the first ionizing light is controlled to continuously change and irradiate any sub-region of a plurality of sub-regions of a sample to be measured, and an ionization spectrum of a fluorescent probe point defect corresponding to the sub-region is determined; wherein the ionization spectrum represents the change in the local electric field of the fluorescent probe point defect after the sub-region is irradiated by the first ionizing light.

[0053] In operation S2, in the case where the ionization spectrum determines that there is an electronic point defect in the sub-region, operations S3-S4 are iteratively performed until the modified ionization spectrum satisfies a preset condition, and the type of the electronic point defect of the sub-region is determined according to the ionization spectrum that satisfies the preset condition; the preset condition is that the energy level information obtained from the characteristic wavelength with a jump amplitude of 0 in the modified ionization spectrum is located in a preset energy level information set.

[0054] In operation S3, a threshold wavelength is determined according to the ionization spectrum, and the threshold wavelength represents a critical wavelength for ionizing all electronic point defects in the sub-region.

[0055] In operation S4, the wavelength range, power and irradiation time of the first ionizing light are modified, and the sub-region is irradiated again using the modified first ionizing light to obtain a modified ionization spectrum; wherein the modified wavelength range is determined according to the threshold wavelength.

[0056] According to the embodiment of the application, the threshold wavelength of the ionization spectrum is iteratively optimized, the wavelength range of the first ionizing light is gradually narrowed, the power and irradiation time of the first ionizing light are constantly matched and adapted, the critical condition for ionizing the electronic point defects in the focused sub-region can be targetedly provided, irrelevant wavelengths and parameters are avoided, and the energy level information detection is more targeted.

[0057] According to the embodiment of the present application, the iterative optimization process can not only determine the ionization spectrum meeting the preset condition, but also determine the energy level characteristics of the electron point defect through multiple parameter adjustments, avoid missing key information due to single iteration, and ensure the accuracy of the type of detected electron point defects. The detection method of the embodiment of the present application uses the fluorescent probe point defects inside the to-be-detected sample as a signal medium to realize the detection of the electron point defects, and does not need to rely on the interaction between the probe and the to-be-detected sample. Therefore, the detection method of the embodiment of the present application can not only detect the electron point defects on the surface of the sample, but also detect the electron point defects inside the sample.

[0058] According to the embodiment of the present application, the to-be-detected sample of the embodiment of the present application can be a block solid, and different electron point defects in the to-be-detected sample can have different charge states. The principle of realizing the detection of the electron point defects in the embodiment of the present application is as follows: the electron point defects in the embodiment of the present application need to have the ability of charge state change, and such electron point defects will form a unique energy level structure in the to-be-detected sample. The ground state energy levels of different types of electron point defects are located at different positions in the energy band. The electron point defects with different charge states respond to the first ionization light of different wavelengths. Specifically, the embodiment of the present application irradiates any sub-region of the to-be-detected sample with the first ionization light, and realizes the detection of the electron point defects through the local electric field detection of the fluorescent probe point defects, without the need for thin film cutting and other treatments on the to-be-detected sample. The detection of the electron point defects of the block solid can be directly realized. The embodiment of the present application only relies on the electric field response of the fluorescent probe point defects itself to complete the signal acquisition, and the physical structure of the solid sample is not changed throughout the process. Therefore, the method provided by the embodiment of the present application is non-destructive to the to-be-detected sample.

[0059] The iterative optimization mechanism of the present application does not need to rely on the fluorescent emission ability of the to-be-detected electron point defects, and does not require a large number of defects to superimpose to generate a macro signal, solving the limitations of the above-mentioned traditional methods in the detection object, concentration adaptability and energy level coverage range, and realizing more universal targeted detection. According to the embodiment of the present application, the to-be-detected sample can be a wide band gap semiconductor, including but not limited to silicon, silicon carbide and diamond.

[0060] According to the embodiment of the present application, the fluorescent probe point defects can already exist inside the to-be-detected sample. If the fluorescent probe point defects do not exist inside the material, the detection method further includes: forming a plurality of fluorescent probe point defects in the to-be-detected sample before operation S1. Illustratively, the fluorescent probe point defects can be obtained through mature probe defect generation technologies such as laser direct writing, electron irradiation and high-temperature annealing.

[0061] Among them, the current laser direct writing method can prepare the required fluorescent probe point defects in the plane at the specified depth of the sample to be measured. Taking diamond as an example, the current technology can generate fluorescent probe point defects at a depth of 30 microns below the diamond surface. This preparation method has significant expandability in the two-dimensional plane inside the sample to be measured. In principle, it can completely cover the spatial defect information in the specified depth range, providing support for large-scale and all-around electron point defect detection.

[0062] According to the embodiments of the present application, the principle of realizing electron point defect detection by using fluorescent probe point defects is as follows.

[0063] The energy level state of the fluorescent probe point defect is determined by the local electric field in which it is located. The energy level state of the fluorescent probe point defect can be reflected by the photoluminescence excitation spectrum of the fluorescent probe point defect (for example, the change of the fluorescence intensity of the fluorescent probe point defect at different wavelengths). The source of the local electric field in which the fluorescent probe point defect is located is diverse, mainly including the bias electric field artificially applied, the inherent self-built electric field and stress field inside the sample to be measured, and the electric field induced by the charge of other electron point defects at the fluorescent probe point defect. When the electron point defects in the sub-region ionize, their charge states will change accordingly. And this change of charge state will further cause the change of the local electric field in which the fluorescent probe point defect corresponding to the sub-region is located.

[0064] Based on the above characteristics, the first ionization light is used to irradiate the sub-region to promote the ionization of the electron point defects in the sub-region. Before and after the ionization event, the photoluminescence excitation spectrum of the fluorescent probe point defect is detected respectively. By comparing the difference between the two groups of spectra, the change of the local electric field in which the fluorescent probe point defect is located caused by the ionization process (i.e. the jump amplitude of the local electric field) can be deduced reversely. It should be noted that the charge state of the electron point defect will change after ionization, and the change rule of the charge state of different types of electron point defects after ionization is different. This change of charge state will directly change the local electric field around it. Therefore, as long as the local electric field in the two states before and after ionization is obtained and compared, the specific type of electron point defect that ionizes can be accurately inferred.

[0065] It should be noted that the charge state change of the electronic point defect can be caused by a random spontaneous process or by other artificial control (including but not limited to electric excitation), in addition to the first ionization photoionization. In the embodiment of the present application, the light excitation method is adopted. At the same time, it is necessary to ensure that the probability of the charge state change of the electronic point defect to be measured is low enough, so that in most cases, the charge state of the electronic point defect to be measured will change only when it is irradiated by the first ionization light. Different methods can be used to reduce the probability of the charge state change of the electronic point defect to be measured in different systems, including but not limited to reducing the temperature of the sample to be measured and reducing the optical power of the ionization light and the excitation light. Based on the above principle, the fluorescent probe point defect in the embodiment of the present application is a point defect that responds to an electric field, and this response can be read out by an optical method. For example, the fluorescent probe point defect can be a nitrogen vacancy color center (i.e. NV color center). The NV color center is composed of one nitrogen atom and one carbon substitutional vacancy, which is equivalent to the size of two atoms, so it is almost impossible to coincide with the electronic point defect. By estimating the concentration of the electronic point defect in the sample to be measured, the arrangement density of the probe defect in the sample to be measured can be controlled to achieve the best detection effect. If the concentration information of the electronic point defect in the sample to be measured is completely missing, the probe defect array (formed by multiple fluorescent probe point defects) can be generated from a low density. If the required information is not detected, one or more new fluorescent probe point defects are generated between the original probe defect array, until the required information of the electronic point defect to be measured is detected. Taking the preparation of the NV color center in diamond as an example, the femtosecond laser direct writing technology can be used in the electronic grade single crystal diamond (containing less than 5 ppb of nitrogen), and the NV color center can be generated in the writing point formed by the focused spot of femtosecond light.

[0066] The response characteristics of the fluorescent probe point defects to the local electric field are determined by their own properties, which can specifically be manifested as a response to the size of the local electric field, or one-dimensional, two-dimensional and three-dimensional components of the local electric field. Taking the NV color center in diamond as an example, the excited state energy level of the NV color center will produce a clear response to the longitudinal electric field (parallel to the axial direction of the NV color center) and the transverse electric field (perpendicular to the axial direction of the NV color center). Based on this characteristic, the local electric field information at the NV color center can be obtained by using the photoluminescence excitation spectrum. The excited state of the NV color center has energy level splitting, forming two characteristic energy levels corresponding to Ex and Ey energy levels. When the excitation light wavelength loaded on the NV color center matches the two energy levels, the NV color center will produce resonance absorption of the photons of the excitation light, forming corresponding fluorescence emission peaks, i.e. Ex and Ey peaks, on the photoluminescence excitation spectrum. The local electric field acting on the NV color center can be decomposed into an electric field component parallel to the axial direction of the NV color center (referred to as parallel electric field) and an electric field component perpendicular to the axial direction of the NV color center (referred to as perpendicular electric field). The electric field parallel to the axial direction of the NV color center will simultaneously act on the Ex and Ey peaks, causing the Ex and Ey peaks to shift in the same direction and with the same amplitude; the electric field perpendicular to the axial direction of the NV color center also simultaneously acts on the Ex and Ey peaks, causing the Ex and Ey peaks to shift in opposite directions with the same amplitude. To quantify the relationship between the above-mentioned shift and the electric field component, the following parameters are set. When no ionizing light is applied, the original frequency of the Ex peak is , and the original frequency of the Ey peak is ; when there is a parallel electric field parallel to the axial direction of the NV color center and a perpendicular electric field perpendicular to the axial direction of the NV color center, the detected frequency of the Ex peak is , and the frequency of the Ey peak is ; when the electric field parallel to the axial direction of the NV color center alone acts on the NV color center, the shift of the two peaks is ; when the electric field perpendicular to the axial direction of the NV color center alone acts on the NV color center, the shift of the Ex peak is , and the shift of the Ey peak is . According to the superposition principle, the total shift of each of the two peaks actually detected is the sum of the contributions of the parallel electric field and the perpendicular electric field. The total shift of the Ex peak is represented by equation (1). The total shift of the Ey peak is represented by equation (2).

[0067] (1);

[0068] (2);

[0069] According to equation (1) and equation (2), we can obtain and .

[0070] (3);

[0071] (4) ;

[0072] In the actual measurement link, the photo-induced fluorescence excitation spectrum of the Ex peak and the Ey peak of each NV color center can be obtained in turn by scanning the second excitation light wavelength. According to the measured spectrum, the spectrum peak positions of the Ex peak and the Ey peak are fitted and analyzed respectively, and then the formula (3) and the formula (4) can be used to calculate and . Combined with the inherent electric field-frequency shift linear response coefficient of the NV color center, the and can be converted into two key components of the local electric field in which the NV color center is located, that is, the electric field component parallel to the axial direction of the NV color center and the electric field component perpendicular to the axial direction of the NV color center, to provide accurate electric field reference data for subsequent electron point defect detection.

[0073] Based on the two electric field components, ionization spectra corresponding to the directions can be constructed. According to the change of the electric field component parallel to the axial direction of the NV color center, combined with the ionization light wavelength scanning data, the ionization spectrum of the direction (the horizontal axis is the ionization light wavelength, and the vertical axis is the electric field jump amplitude in the parallel direction) is formed. Similarly, according to the change of the electric field perpendicular to the axial direction of the NV color center as the core parameter, the ionization spectrum of the vertical direction is constructed. Since the fluorescence probe point defects may have different responses to the electric field components in different directions, the ionization spectra of the two directions will show different electric field jump amplitude characteristics. In order to maximize the recognition degree of the ionization signal and the accuracy of subsequent concentration calculation, the ionization spectra of the two directions can be compared and screened in the embodiment of the present application, and the ionization spectrum with the largest electric field jump amplitude change is selected as the ionization spectrum used in the present application.

[0074] According to the embodiment of the present application, after the fluorescent probe point defects are formed in the sample to be measured, the position of the fluorescent probe point defects needs to be determined, and the position of the fluorescent probe point defects can be located by using an optical method. The optical method used for positioning includes but is not limited to confocal microscope imaging method, wide-field imaging microscope imaging method, super-resolution microscope imaging method, etc. In a specific operation, a plane generated by the fluorescent probe point defects of the sample to be measured is scanned by using first excitation light, and the energy of the first excitation light can effectively excite the fluorescent probe point defects to emit light. When the first excitation light scans to the position of the fluorescent probe point defects, the fluorescent probe point defects will emit fluorescence under the action of the first excitation light. The fluorescence emitted by the probe point defects is captured by combining the selected optical imaging method, and the position of the fluorescent probe point defects is determined according to the spatial position information of the fluorescence in the sample to be measured. The wavelength of the first excitation light is unchanged, and the wavelength of the first excitation light only needs to match the excitation wavelength band of the probe to ensure that the fluorescence can be excited. It should be noted that when the first excitation light continuously irradiates the fluorescent probe point defects, the electric field around the fluorescent probe point defects can be reset. The principle is that when the fluorescent probe point defects are irradiated by the first excitation light, the process of continuous ionization and charging occurs, thereby emitting electrons and holes to the whole space, so as to reset the electric field around the fluorescent probe point defects.

[0075] In operation S1, for example, if it is necessary to detect the electronic point defects in a certain to-be-measured region in the sample to be measured, a plurality of probe point defects need to be formed in the to-be-measured region. The plurality of sub-regions of the sample to be measured are the plurality of sub-regions in the to-be-measured region.

[0076] According to the detection method provided by the embodiment of the present application, at least one fluorescent probe point defect corresponds to each sub-region, so that the electronic point defects in the sub-region can be detected. It should be noted that the fluorescent probe point defect corresponding to each sub-region has the following characteristics: when there are electronic point defects in the sub-region, the local electric field of the fluorescent probe point defect will be affected by the electronic point defects.

[0077] According to the embodiment of the present application, in operation S1, for any sub-region, the first ionizing light is used to irradiate the sub-region for multiple times, and the wavelength of the first ionizing light changes in multiple irradiations. In multiple irradiations, the wavelength of the first ionizing light changes according to a preset rule. However, no matter how the wavelength of the first ionizing light changes, the wavelength of the first ionizing light is always within the wavelength range. For example, the first ionizing light irradiates the sub-region N times, the wavelength of the first ionizing light is λ1 in the first irradiation, the wavelength of the first ionizing light is λi in the i th irradiation, and the wavelength of the first ionizing light is λN in the N th irradiation, 1≤i≤N, λ1~λN, and λi changes according to a preset rule, for example, increases or decreases in turn. i N N ​​​

[0078] The determination process of the ionization spectrum of the fluorescent probe point defect corresponding to the above-mentioned sub-region is as follows: before the i-th irradiation, the fluorescent probe point defect corresponding to the sub-region is irradiated by the second excitation light so that the fluorescent probe point defect emits fluorescence, and the fluorescence intensity is counted; after the i-th irradiation, the fluorescent probe point defect corresponding to the sub-region is irradiated by the second excitation light so that the fluorescent probe point defect emits fluorescence, and the fluorescence intensity is counted. The second excitation light is scanning light with continuously changing wavelength. The photon energy range of the second excitation light needs to be near the excitation energy level of the fluorescent probe point defect. The power of the second excitation light needs to be controlled at a low level, usually in the order of ten to one hundred nanowatts. Here, still taking the NV color center as an example, the power of the second excitation light needs to be sufficient to excite the NV color center to generate a detectable fluorescence signal, and also needs to avoid interfering with the charge state of the electronic point defect, preventing the charge state of the electronic point defect to be detected from changing due to the excessively high light power, and ensuring that the signal difference after ionization relative to that before ionization is only caused by the local electric field change caused by the ionization of the electronic point defect after the first ionization light irradiation.

[0079] By measuring the change of the fluorescence intensity of the fluorescent probe point defect under the second excitation light at each wavelength before the 1st to Nth irradiation (ionization), the photo-induced fluorescence excitation spectrum of the fluorescent probe point defect of the point defect to be detected before ionization can be obtained. By measuring the change of the fluorescence intensity of the fluorescent probe point defect under the second excitation light at each wavelength after the 1st to Nth irradiation (ionization), the photo-induced fluorescence excitation spectrum of the fluorescent probe point defect of the point defect to be detected after ionization can be obtained. According to the photo-induced fluorescence excitation spectrum before the ionization of the electronic point defect and the photo-induced fluorescence excitation spectrum after the ionization of the electronic point defect, the jump amplitude of the local electric field in which the fluorescent probe point defect is located caused by the first ionization light irradiation can be obtained. In other words, the jump amplitude generation process here can be understood as follows: the local electric field in which the fluorescent probe point defect is located after the sub-region is irradiated by the first ionization light will change relative to the local electric field in which the fluorescent probe point defect is located before the sub-region is irradiated by the first ionization light. The jump amplitude here can be understood as the size of the change. By changing the wavelength of the first ionization light, the change rule of the jump amplitude of the local electric field with the wavelength is measured and recorded, and the obtained curve is the ionization spectrum of the point defect.

[0080] According to the embodiments of the present application, in operation S1, for a specific semiconductor, the energy band structure thereof can be obtained by known theory or previous characterization, and the upper limit of the photon energy of the first ionization light can be determined accordingly. If the electronic point defect inside the semiconductor of a known material needs to be detected, the electronic point defect can be preliminarily ionized by the ionization light with a wavelength close to the band gap of the semiconductor, and then the wavelength of the first ionization light is gradually increased, and the ionization spectrum is constructed according to the electric field jump amplitude detected by the fluorescent probe point defect.

[0081] In certain semiconductors, the type of potential electron point defects can also be inferred in combination with the process flow, such as through doping information of certain atoms, gas environment during preparation, etc., to infer the type of potential electron point defects that can be contained in the semiconductor. With the development of the semiconductor industry, the energy levels of the electron point defects of most commonly used semiconductors have been systematically characterized. In combination with the process flow and existing experimental data, the energy level of the deepest electron point defect in most commonly used semiconductors can be accurately located (in the semiconductor field, the closer the defect energy level is to the valence band, the deeper the energy level is generally considered to be). If there is no information about the electron point defects, the above wavelength screening method of gradually increasing the wavelength from the band gap wavelength can be used; if there is relevant information or effective experience support, the appropriate wavelength can be directly selected according to this, and the construction efficiency of the ionization spectrum can be improved.

[0082] Assuming that there is no information about the electron point defects at all, when the first ionizing light irradiates the sub-region for the first time, the wavelength range of the first ionizing light can be, for example, 500 nm-760 nm, the power of the first ionizing light can be, for example, 8 mW, which can be set as the maximum power that the sample to be measured can withstand in principle, and the irradiation time of the first ionizing light can be, for example, 10 seconds. The irradiation of the sub-region by the first ionizing light with the above parameters can ensure that all electron point defects of the sub-region are ionized by the first ionizing light.

[0083] According to the embodiments of the present application, the detection of the multiple fluorescent probe point defects in the sample to be measured can be alternately performed or simultaneously performed; and the measurement of the fluorescent probe point defects needs to reach a certain sensitivity to ensure that the electric field signal with sufficient signal-to-noise ratio is obtained before the charge state of the electron point defect to be measured changes, so as to effectively distinguish the local electric field change caused by the charge state change of the electron point defect to be measured.

[0084] According to the embodiments of the present application, in operation S2, determining that the sub-region contains the electron point defects according to the ionization spectrum includes: in the case that the jump amplitude of the local electric field of the fluorescent probe point defect is not 0 in the ionization spectrum, determining that the sub-region contains the electron point defects. Otherwise, in the case that the jump amplitude of the local electric field of the fluorescent probe point defect is 0 for all wavelengths in the ionization spectrum, determining that the sub-region does not contain the electron point defects.

[0085] According to the embodiments of the present application, after the threshold wavelength is obtained, the above detection method further includes the following operations.

[0086] Irradiating the sub-region with the second ionizing light to determine the power spectrum of the fluorescent probe point defect corresponding to the sub-region; wherein the power spectrum represents the change of the jump amplitude of the local electric field of the fluorescent probe point defect after the irradiation of the second ionizing light with the power; wherein the wavelength of the second ionizing light is the threshold wavelength. And obtaining the threshold power from the power spectrum, the threshold power represents the critical power for ionizing all electron point defects in the sub-region.

[0087] According to the embodiment of the present application, the threshold wavelength determined by the ionization spectrum is the fixed wavelength of the second ionizing light, which can match the ionizing light photon energy of the second ionizing light with the electron point defect energy level as much as possible. On this basis, by analyzing the change of the jump amplitude with the power through the power spectrum, the threshold power that can ionize all the electron point defects in the sub-region can be obtained.

[0088] According to the embodiment of the present application, the threshold power is valuable to ensure that all the electron point defects in the sub-region are ionized, avoiding the problem that some electron point defects are not ionized due to insufficient power, and further causing the problem of underestimating the number of electron point defects and the deviation of the concentration calculation. Especially for the low-concentration defect scene, the determination of the threshold power can maximize the excitation of the electron point defects at a smaller power.

[0089] According to the embodiment of the present application, in the power spectrum, as the power increases, the jump amplitude of the fluorescent probe point defect gradually increases (more electron point defects are ionized), and when the power is raised to a certain value, the jump amplitude no longer increases obviously, and the inflection point from the continuous growth to the stable trend is the threshold power.

[0090] According to the embodiment of the present application, the power spectrum can further reveal the ionization characteristics of the electron point defects: for example, when the jump amplitude in the power spectrum changes linearly with the power, it can be determined as a single-photon ionization process, reflecting the characteristics that the energy level of the electron point defect can be directly ionized between the conduction band of the sample to be measured (which can be a semiconductor); if it presents a nonlinear change, it may correspond to a complex mechanism such as two-photon ionization. The power spectrum supplements the basic information of the energy level that can be obtained by the ionization spectrum, makes the physical characteristics of the electron point defects more comprehensive, and provides more dimensional basis for accurate determination of the type of electron point defects.

[0091] According to the embodiment of the present application, after obtaining the threshold wavelength, the above detection method further includes the following operations.

[0092] The sub-region is irradiated by the third ionizing light to determine the time spectrum of the fluorescent probe point defect corresponding to the sub-region; the time spectrum represents the change of the jump amplitude of the local electric field of the fluorescent probe point defect after the irradiation of the third ionizing light with the irradiation time; wherein the wavelength of the third ionizing light is the threshold wavelength; the threshold time is obtained according to the time spectrum, and the threshold time represents the critical time length for ionizing all the electron point defects in the sub-region. And, the threshold time is obtained according to the time spectrum, and the threshold time represents the critical time length for ionizing all the electron point defects in the sub-region.

[0093] The time spectrum can clearly present the time response rule of the ionization of the electron point defect by quantifying the corresponding relationship between the jump amplitude of the local electric field of the fluorescent probe point defect and the irradiation time length. The jump amplitude increases to a turning point which tends to be stable with the increase of the irradiation time length, and the turning point is the threshold time length. The ionization cross-section information of the electron point defect in the sub-region can be obtained by performing exponential fitting on the time spectrum. The information can be used to assist in determining the type of the electron point defect.

[0094] According to an embodiment of the present application, the measurement sequence of the power spectrum and the time spectrum can be interchanged, that is, the power spectrum can be measured first and then the time spectrum can be measured, or the time spectrum can be measured first and then the power spectrum can be measured.

[0095] According to an embodiment of the present application, the power spectrum and the time spectrum can also be used to determine whether the number of the electron point defect in the sub-region is one. Specifically, the method for determining whether the number of the electron point defect in the sub-region is one by using the time spectrum includes: after the irradiation time length of the third ionizing light is increased to a certain value, the jump amplitude of the fluorescent probe point defect occurs a step change from 0 to another value, and it can be determined that the number of the electron point defect in the sub-region is one. The method for determining whether the number of the electron point defect in the sub-region is one by using the power spectrum includes: after the irradiation power of the second ionizing light is increased to a certain value, the jump amplitude of the fluorescent probe point defect occurs a step change from 0 to another value, and it can be determined that the number of the electron point defect in the sub-region is one. In contrast, although the traditional deep level optical spectroscopy (DLOS) can study the response of the to-be-measured electron point defect to the applied ionizing light, its core relies on the measurement of the photocurrent generated by the ionization of the ionizing light. This method has a hard requirement for the defect concentration, and the intensity of the photocurrent signal is directly related to the number of the electron point defects participating in the ionization. When the number of the to-be-measured electron point defect in the sub-region is insufficient, the photocurrent generated by the ionization is extremely weak, far below the lower limit of the sensitivity of the conventional detection equipment, resulting in that the ionization response signal in the low-concentration and single-electron point defect scenario cannot be captured.

[0096] Illustratively, in the case of measuring the power spectrum first and then measuring the time spectrum, in the case of determining that the number of the electron point defect in the sub-region is one by using the power spectrum, the above method further includes: repeating the process of measuring the power spectrum multiple times to obtain multiple power spectra, and obtaining the jump probability of the fluorescent probe point defect at different powers (different powers of the second ionizing light) according to the multiple power spectra, that is, a first probability spectrum. Then, the jump probability of the fluorescent probe point defect at different irradiation time lengths (different irradiation time lengths of the third ionizing light) is obtained according to the multiple time spectra, that is, a second probability spectrum. In the case of measuring the time spectrum first and then measuring the power spectrum, and similar to the above method, the first probability spectrum and the second probability spectrum are respectively obtained in the case of determining that the number of the electron point defect in the sub-region is one.

[0097] According to the embodiment of the present application, when the power spectrum is measured first and then the time spectrum is measured, the irradiation time of the second ionizing light is the same as the irradiation time of the first ionizing light, the wavelength of the second ionizing light is the threshold wavelength obtained according to the ionization spectrum, the power gradually increases from 1 micro-watt, and the maximum power is the power corresponding to the maximum local electric field jump amplitude in the power spectrum or the maximum jump probability in the first probability spectrum. The power of the third ionizing light is the threshold power obtained according to the power spectrum, the wavelength is the threshold wavelength obtained according to the ionization spectrum, and the irradiation time gradually increases from 100 nanoseconds. When the time spectrum is measured first and then the power spectrum is measured, the irradiation time of the third ionizing light gradually increases from 0, and the maximum irradiation time is the irradiation time corresponding to the maximum local electric field jump amplitude in the time spectrum or the maximum jump probability in the second probability spectrum.

[0098] According to the embodiment of the present application, when the number of electron point defects in the sub-region is determined to be 1 according to the time spectrum or the power spectrum, the threshold wavelength is determined according to the ionization spectrum, including operations A-D.

[0099] In operation A, a plurality of ionization spectra of the fluorescent probe point defects corresponding to the sub-region are determined.

[0100] In operation B, for any wavelength in the first range, the jump amplitude at the wavelength in the plurality of ionization spectra is obtained.

[0101] In operation C, the jump probability of the fluorescent probe point defects at any wavelength is obtained according to the jump amplitude at the wavelength in the plurality of ionization spectra.

[0102] In operation D, the jump probability spectrum is obtained according to the jump probability at all wavelengths in the first range.

[0103] In operation E, the threshold wavelength is determined according to the jump probability spectrum.

[0104] According to the embodiment of the present application, when the number of the electron point defects in the sub-region is one, the ionization state thereof only has two cases of non-ionization and ionization. Since the jump amplitude of the fluorescent probe point defect caused by the ionization of the one electron point defect is fixed, the jump amplitude of the local electric field perceived by the fluorescent probe point defect also only corresponds to two results of 0 or a fixed value. When the jump amplitude is 0, it indicates that there is no jump at the corresponding wavelength. When the jump amplitude is a fixed value, it indicates that a jump occurs at the corresponding wavelength. In principle, when the one electron point defect in the sub-region is ionized at a certain wavelength, the one electron point defect in the sub-region will be ionized at any wavelength less than the wavelength. Therefore, the maximum wavelength that can cause the one electron point defect in the sub-region to jump, which is determined according to the ionization spectrum, is the threshold wavelength. The jump amplitudes of all ionization spectra at the same wavelength are counted (for example, the jump amplitudes of all ionization spectra at the same wavelength are measured 400 times), the jump probability (i.e., the number of jumps divided by the number of measurements) is obtained, the threshold wavelength is determined according to the jump probability, the random noise such as environmental interference is averaged, the signal distortion caused by accidental noise in single detection is avoided, and more stable data basis is provided for subsequent data processing.

[0105] It should be noted that the size of the sub-region in the to-be-detected region is related to the spot of the ionizing light irradiated on the sub-region.

[0106] It is assumed that the to-be-detected region to be detected is a space region in the to-be-detected sample in the shape of a cuboid. Before detection, the space region needs to be discretized first, i.e., the space region is divided into multiple sub-regions. The parameters required for discretization are the size and shape of the spot of any ionizing light irradiated on the sub-region. The size of the sub-region is described below by taking the first ionizing light irradiated on the to-be-detected region as an example.

[0107] Specifically, when the first ionizing light is used to irradiate the to-be-tested region, the first ionizing light can be focused on the to-be-tested region by using the objective lens, and an energy acting region is formed on the to-be-tested region, the acting region is a light spot of the first ionizing light, and the ellipsoid shape is the form of the light spot of the first ionizing light. The parameters required for spatial discretization are determined by two key conditions: one is the specification parameter of the selected objective lens, and the other is the wavelength of the first ionizing light; the light spot power distribution characteristics formed inside the to-be-tested sample after the first ionizing light is focused by the objective lens can be calculated by using the diffraction formula in combination with the two parameters. With the help of the diffraction formula, the parameters of the ellipsoid can be further calculated, that is, the lengths of two equal characteristic axes in the focusing plane (a plane perpendicular to the transmission direction of the first ionizing light) and the length of the characteristic axis in the direction perpendicular to the focusing plane (a plane parallel to the transmission direction of the first ionizing light). Based on the calculated characteristic axis lengths, a cuboid that can exactly wrap the ellipsoid is determined, and the cuboid is used as a subregion. If the power of the first ionizing light is changed, the size of the ellipsoid will be changed, and thus the size of the subregion will be changed, therefore, the parameters of the first ionizing light need to be determined according to the properties of the electronic point defects. The above analysis shows that when different ionizing lights are used to irradiate the to-be-tested region of the to-be-tested sample, the sizes of the subregions of the to-be-tested region can be different.

[0108] Figure 2 A schematic diagram of the longitudinal energy distribution of the light spot of the first ionizing light obtained by simulation is shown.

[0109] The focusing plane is located in the XY plane for example, and the length of the characteristic axis of the ellipsoid in the X direction can be determined according to the longitudinal energy of the light spot of the first ionizing light, which is a. The length of the characteristic axis of the ellipsoid in the Z direction perpendicular to the focusing plane is b, and since Figure 2 The plane shown is the plane determined by the X direction and the Z direction, so the length of the characteristic axis of the light spot of the first ionizing light in the Y direction perpendicular to the X direction and the Z direction cannot be seen, and in fact, the length of the characteristic axis of the ellipsoid in the Y direction is also a. It should be noted that when the light spot of the first ionizing light is used to irradiate the subregion, the energy component of the light spot of the first ionizing light located in the subregion is considered as the main energy component of the electronic point defects in the ionized region.

[0110] Figure 3 A schematic diagram of a plurality of subregions included in the to-be-tested region is shown.

[0111] As Figure 3 shown, the large cuboid is the to-be-tested region inside the to-be-tested sample, which is represented by V in the figure, and the small cuboid is a subregion, which is the smallest detection unit after V is discretized. The size of each subregion is determined by the light spot parameters of the first ionizing light, Figure 3 The length and width of the small square are a (correspondingFigure 2 b (corresponding to the length of the characteristic axis of the ellipsoid in the focusing plane), and height b (corresponding to the length of the characteristic axis of the ellipsoid in the direction perpendicular to the focusing plane). Figure 2 b (corresponding to the length of the characteristic axis of the ellipsoid in the focusing plane), and height b (corresponding to the length of the characteristic axis of the ellipsoid in the direction perpendicular to the focusing plane).

[0112] It should be noted that when the ionizing light with different powers is used to irradiate the to-be-measured region, the sizes and shapes of the light spots generated by ionizing lights with different powers are different, and therefore the sub-regions corresponding to ionizing lights with different powers are different.

[0113] According to an embodiment of the present application, in operation S4, the changed wavelength range is determined according to the threshold wavelength, including that the minimum wavelength of the changed wavelength range is the threshold wavelength. According to an embodiment of the present application, the maximum wavelength of the changed wavelength range is the maximum wavelength of the wavelength range in S1.

[0114] According to an embodiment of the present application, in operation S4, the power and the irradiation time of the first ionizing light are changed, including that the power of the first ionizing light is changed to the threshold power, and the irradiation time of the first ionizing light is changed to the threshold time.

[0115] It should be particularly noted that the determination of the type of electronic point defects by using the most initial ionization spectrum, the most initial power spectrum and the most initial time spectrum obtained by the above operation may ignore the fine energy level structure of the electronic point defects.

[0116] Figure 4 An energy level structure of a point defect according to an embodiment of the present application is shown.

[0117] As shown in Figure 4 the energy level of the electronic point defect is located between the conduction band (referred to as conduction band) of the to-be-measured sample and the valence band (referred to as valence band) of the to-be-measured sample, and the band gap energy of the to-be-measured sample is between the bottom of the conduction band and the top of the valence band. According to the energy level of the electronic point defect, it can be seen that there are two ionization (transition) paths of the electronic point defect, the first one is a direct ionization path from the ground state energy level to the conduction band energy level (corresponding to single-photon ionization), and the second one is an indirect ionization path from the ground state energy level to the excited state energy level, and then from the excited state energy level to the conduction band (corresponding to two-photon ionization).

[0118] The condition for single-photon ionization is that the energy provided by a single photon of the first ionizing light (ionizing light) is equal to or higher than the energy difference of the electron point defect from the ground state energy level to the conduction band, and the electron point defect does not need to be superimposed by multiple photons, but can complete ionization (the electron jumps from the ground state to the conduction band to realize the charge state change) by absorbing only one photon. The ionization does not need the first ionizing light to have high power, but only needs to meet the above condition. The condition for multi-photon ionization is that when the energy of a single photon of the first ionizing light is lower than the energy difference of the ground state to the conduction band of the electron point defect to be tested, the number of photons in a unit time is increased by increasing the power of the first ionizing light, so that the electron point defect absorbs multiple photons at the same time or in sequence, and the total energy after superposition reaches the ionization requirement to complete ionization.

[0119] Since the power of the first ionizing light applied in the operation is large and the irradiation time is long, the irradiation of the first ionizing light on the sub-region in the operation can cause the electron point defect to undergo a single-photon ionization process or simultaneously undergo a single-photon ionization process and a two-photon ionization process.

[0120] In order to more accurately determine the type of the electron point defect, in the embodiment of the present application, the wavelength range of the first ionizing light is continuously changed, and the power and irradiation time of the first ionizing light are reduced, so that different electron point defects can as far as possible undergo the same ionization process. For example, the power and irradiation time of the first ionizing light are reduced, and the wavelength range of the first ionizing light is changed. In the last iteration, the first ionizing light needs to ensure that all the electron point defects in the sub-region irradiated by the first ionizing light are ionized at the same time, and the electron point defects in the sub-region are mainly ionized by single-photon ionization. Finally, the energy level information can be determined by using the ionization spectrum that meets the preset condition, and the type of the electron point defect can be determined according to the energy level information.

[0121] According to the embodiment of the present application, the threshold wavelength is used as the minimum wavelength of the changed wavelength range, so that the first ionizing light in the iteration process can always ensure the ionization of the electron point defects in the sub-region. At the same time, the power of the first ionizing light is fixed as the threshold power, and the irradiation time is fixed as the threshold time, both of which are critical parameters verified by the power spectrum and the time spectrum, and can make all the electron point defects in the sub-region completely ionized when the first ionizing light uses the threshold wavelength of the current iteration round. The threshold power can avoid that the high power leads to a large photon density (a key inducement of two-photon ionization); and the threshold time ensures that the ionization is completed under the premise of sufficient energy. In the embodiment of the present application, by continuously narrowing the wavelength range of the first ionizing light and continuously reducing the power and irradiation time of the first ionizing light, it can be ensured that the ionization process of the electron point defect is always dominated by single-photon ionization, and accurate and interference-free spectral basis is provided for subsequent determination of the type of the electron point defect.

[0122] According to an embodiment of the present application, the type of the electronic point defect of the sub-region is determined according to the ionization spectrum satisfying the preset condition, comprising: determining the type of the electronic point defect according to the energy level information obtained from the characteristic wavelength in the ionization spectrum satisfying the preset condition and the mapping relationship between the energy level information and the type of the electronic point defect.

[0123] According to an embodiment of the present application, in the iteration process, since the power of the first ionizing light is continuously reduced and the irradiation time is continuously reduced, the occurrence of multiphoton ionization can be effectively inhibited, and the ionization process of the electronic point defect is gradually guided to change to single-photon ionization domination. The specific principle is as follows.

[0124] In the initial iteration stage, in order to ensure that all electronic point defects in the sub-region can be ionized, the first ionizing light uses a higher power and a longer irradiation time, at this time, single-photon ionization and multiphoton ionization processes may exist at the same time, and it is difficult to accurately capture the fine energy level characteristics of the electronic point defect. With the advancement of iteration, based on the threshold wavelength determined according to the ionization spectrum of the previous round, the wavelength range of the first ionizing light is gradually reduced, and at the same time, the threshold power obtained from the power spectrum and the threshold time obtained from the time spectrum are combined to continuously reduce the power and irradiation time of the first ionizing light. This adjustment not only ensures that the ionizing light energy can still meet the ionization needs of the electronic point defect (the threshold parameter ensures that all defects can be ionized), but also greatly reduces the photon density per unit time, avoiding the absorption of multiple photons by the electronic point defect to complete ionization.

[0125] After multiple rounds of iteration optimization, the parameters of the first ionizing light are accurately matched to the single-photon ionization conditions of the electronic point defect: the wavelength range is directly matched to the interval of the electronic point defect energy level, the power and the irradiation time exactly meet the requirements that a single photon can excite the electron to jump from the ground state to the conduction band, and finally all electronic point defects in the sub-region are dominated by single-photon ionization to complete ionization in the last iteration. From the ionization spectrum satisfying the preset condition, all characteristic wavelengths with a jump amplitude of 0 are extracted. These characteristic wavelengths are the key identifiers of the single-photon ionization of the electronic point defect. Since the core principle of single-photon ionization is that the photon energy is equal to the energy difference between the ground state energy level of the electronic point defect and the conduction band energy level of the sample to be measured, each characteristic wavelength corresponds to an explicit energy level difference. Calculate the photon energy corresponding to each characteristic wavelength, which is the ionization energy required for the electronic point defect to jump from the ground state to the conduction band, and then deduce the ground state energy level information of the electronic point defect. Compare and match the deduced ground state energy level information of the electronic point defect with the standard energy level in the preset energy level information set. If the target energy level information completely coincides with (or is within a preset error range) the standard energy level of a certain type of electronic point defect in the set, it is directly determined that the electronic point defect in the sub-region is of that type.

[0126] According to embodiments of the present invention, energy level information is derived based on characteristic wavelengths in the ionization spectrum, ensuring the authenticity and validity of the energy level information. The ionization spectrum meeting preset conditions is a key parameter locked through multiple rounds of iterative optimization to match the ionization energy levels of electronic point defects. Furthermore, the preset conditions filter out invalid energy level information, avoiding potential misjudgments of energy levels during the iteration process, and providing a reliable core basis for defect type matching.

[0127] The embodiments of the present invention can evaluate the charge dynamics of electronic point defects by individually changing the wavelength range, power and irradiation time of the first ionizing light. Therefore, by combining the synergistic information of the ionization spectrum, power spectrum and time spectrum during the iteration process, and combining the material properties of the sample to be tested, the multidimensional physical characteristics of the electronic point defects to be tested can be fully constructed, thereby realizing the determination of their types.

[0128] According to an embodiment of the present invention, for a target sub-region containing electronic point defects and having a number of electronic point defects not equal to one, after determining the types of electronic point defects in the target sub-region, when multiple types of electronic point defects exist in the target sub-region, it is necessary to obtain the concentration information of each type of electronic point defect in the target sub-region. When detecting any target type of electronic point defect, it is necessary to ensure that the electronic point defect of that target type is completely ionized. Only by ensuring the integrity of ionization can the total charge of the electronic point defect of that target type be accurately deduced from the electric field change amplitude, and thus the concentration can be calculated. For any target type of electronic point defect, a fourth ionization light is used to ionize it. The wavelength of the fourth ionization light is selected to ensure that all electronic point defects of that target type in the target sub-region are completely ionized, and that it is single-photon ionization, so as to ensure that the total jump amplitude can truly reflect the total charge of the defects in the region, and to eliminate the interference of incomplete ionization for subsequent counting. After the types of electronic point defects in the target sub-region are determined, the wavelength of the fourth ionization light required for each electronic point defect is also determined.

[0129] Figure 5 The relative positional relationship between any sub-region provided according to an embodiment of the present invention and the corresponding fluorescent probe point defect is shown.

[0130] exist Figure 5 In the diagram, the center of the target sub-region K1 is K2, and the location of the fluorescent probe point defect corresponding to this target sub-region is K3.

[0131] The following combination Figure 5 A method for determining the number and concentration of electronic point defects of any target type in a target sub-region is described.

[0132] In operation S5, the target sub-region K1 is irradiated with fourth ionizing light to obtain the total jump amplitude of the local electric field of the fluorescent probe point defect corresponding to the target sub-region K1 after irradiation with fourth ionizing light. ; the wavelength of the fourth ionizing light is a wavelength that causes single-photon ionization of any target species of electronic point defects in the target sub-region K1. The power of the fourth ionizing light is the threshold power obtained in the last iteration. The corresponding target sub-region of the fourth ionizing light is the same as the sub-region corresponding to the first ionizing light in the last iteration.

[0133] In operation S6, the unit jump amplitude of the target sub-region K1 corresponding to the fluorescent probe point defects of the target species of electronic point defects in the target sub-region K1 is obtained when the center position K2 of the target sub-region K1 is located at the center position K2. .

[0134] In operation S7, the number n and the concentration of the target species of electronic point defects in the target sub-region are determined according to the total jump amplitude and the unit jump amplitude . The number n, the concentration , the total jump amplitude , and the unit jump amplitude satisfy the following relationship.

[0135] (5).

[0136] (6).

[0137] Figure 6 An energy level diagram of a plurality of electronic point defects that a sub-region can include is shown.

[0138] As shown in Figure 6 , taking three electronic point defects included in a sub-region as an example, from left to right, the energy level of the first electronic point defect, the energy level of the second electronic point defect, and the energy level of the third electronic point defect are sequentially arranged. The energy levels of the above three electronic point defects are sequentially marked as the first energy level, the second energy level, and the third energy level in Figure 6 . The first electronic point defect and the second electronic point defect both have a ground state energy level and an excited state energy level. The ground state energy level of the first electronic point defect is closer to the valence band of the sample to be measured than the ground state energy level of the second electronic point defect. The excited state energy level of the second electronic point defect is closer to the conduction band of the sample to be measured than the excited energy level of the first electronic point defect. The third electronic point defect only has a ground state energy level and does not have an excited state energy level.

[0139] If the sub-region contains the three types of electronic point defects mentioned above, and each type requires a different wavelength of fourth ionization light, then given the existence of these three types of electronic point defects within the sub-region, the wavelengths of the fourth ionization light corresponding to each type of electronic point defect can be directly determined. When using fourth ionization light to detect the number and concentration of different types of electronic point defects in a sub-region, the electronic point defects with longer wavelengths of the corresponding fourth ionization light should be detected first. If the sub-region is irradiated with fourth ionization light of shorter wavelengths first, the fourth ionization light will ionize the various undetected electronic point defects in the sub-region, resulting in inaccurate detection results.

[0140] Figure 7 A schematic diagram of a detection device provided according to an embodiment of the present invention is shown. This detection device is used to implement the above-described method for detecting electronic point defects.

[0141] like Figure 7 As shown, the detection device includes: a light generation module 1, a movable objective lens 3, a fluorescence collection module 4, a processing module 5, and a dichroic mirror 6.

[0142] According to an embodiment of the present invention, the light generation module 1 is used to generate a first excitation light, a second excitation light, a first ionization light, a second ionization light, a third ionization light, and a fourth ionization light in a sequential manner. The dichroic mirror 6 is used to reflect the light signals generated by the light generation module to the movable objective lens 3, which is adapted to focus the received light signals onto the sample 2 to be tested.

[0143] After fluorescent probe point defects are formed in the test sample 2, excitation light is generated by the light generation module 1. The excitation light scans various positions of the test sample to excite the fluorescent probe point defects, causing them to emit fluorescence. The location of the fluorescent probe point defects can be determined based on the location of the fluorescence emission. Then, before each sub-region is irradiated with ionization light, the corresponding fluorescent probe point defects are irradiated with a second excitation light to cause them to emit fluorescence. The movable objective lens 3 is also used to transmit the fluorescence emitted by the fluorescent probe point defects to the fluorescence collection module 4. The fluorescence collection module 4 is used to statistically analyze the fluorescence emitted by the fluorescent probe point defects before and after ionization light is applied to each sub-region. The processing module 5 is used to obtain the ionization spectrum, power spectrum, and time spectrum based on the statistical results, and to determine the type of electronic point defects in the sub-region based on the ionization spectrum, power spectrum, and time spectrum.

[0144] According to the embodiment of the present application, the movable objective is located on a displacement table, the spatial position of the movable objective 3 can be controlled by the displacement table, the focusing position of any ionized light is changed, and the type number, concentration distribution result and type distribution result of the electron point defects in any sub-region are obtained.

[0145] The detection method provided by the embodiment of the present application solves the limitation that the traditional method can only preliminarily judge the existence of the electron point defects and is difficult to deeply obtain the core physical parameters, and provides deeper technical support for semiconductor material doping optimization and quantum defect characteristic research.

Claims

1. A method for detecting electronic point defects, characterized in that, include: The wavelength of the first ionizing light is controlled to vary within a wavelength range and irradiate any one of the multiple sub-regions of the sample to be tested, thereby determining the ionization spectrum of the fluorescent probe point defect corresponding to the sub-region; wherein, the ionization spectrum characterizes the change in the amplitude of the jump in the local electric field of the fluorescent probe point defect after irradiation by the first ionizing light as a function of wavelength. If an electron point defect is determined to exist in the sub-region based on the ionization spectrum, the following operations are performed iteratively until the modified ionization spectrum meets a preset condition, and the type of electron point defect in the sub-region is determined based on the ionization spectrum that meets the preset condition; the preset condition is that the energy level information obtained from the characteristic wavelength with a non-zero jump amplitude in the modified ionization spectrum is within a preset energy level information set: A threshold wavelength is determined based on the ionization spectrum, the threshold wavelength being a critical wavelength that causes all electron point defects in the sub-region to ionize. The wavelength range, power, and irradiation duration of the first ionizing light are changed, and the sub-region is re-irradiated with the changed first ionizing light to obtain the changed ionization spectrum; wherein the changed wavelength range is determined based on the threshold wavelength.

2. The detection method according to claim 1, characterized in that, The modified wavelength range, determined based on the threshold wavelength, includes: The minimum wavelength of the modified wavelength range is the threshold wavelength.

3. The detection method according to claim 1, characterized in that, After obtaining the threshold wavelength, the detection method further includes: The sub-region is irradiated with second ionizing light to determine the power spectrum of the fluorescent probe point defect corresponding to the sub-region; wherein, the power spectrum characterizes the change in the amplitude of the jump in the local electric field of the fluorescent probe point defect after irradiation with the second ionizing light as a function of power; wherein, the wavelength of the second ionizing light is the threshold wavelength; The threshold power is obtained from the power spectrum, and the threshold power characterizes the critical power that ionizes all electronic point defects in the sub-region.

4. The detection method according to claim 3, characterized in that, After obtaining the threshold wavelength, the detection method further includes: The sub-region is irradiated with third ionizing light to determine the temporal spectrum of the fluorescent probe point defect corresponding to the sub-region; the temporal spectrum characterizes the change in the amplitude of the jump of the local electric field of the fluorescent probe point defect after irradiation with the duration of irradiation; wherein the wavelength of the third ionizing light is the threshold wavelength. The threshold duration is obtained from the time spectrum, and the threshold duration represents the critical duration for ionizing all electronic point defects in the sub-region.

5. The detection method according to claim 4, characterized in that, Changing the power and irradiation duration of the first ionizing light includes: The power of the first ionizing light is changed to the threshold power, and the irradiation time of the first ionizing light is changed to the threshold time.

6. The detection method according to claim 1, characterized in that, Determining the presence of electronic point defects within the sub-region based on the ionization spectrum includes: If the jump amplitude of the local electric field of the fluorescent probe point defect in the ionization spectrum is not zero, it is determined that there is an electronic point defect in the sub-region.

7. The detection method according to claim 1, characterized in that, The types of electronic point defects in the sub-region are determined based on the ionization spectrum that meets preset conditions, including: The type of electronic point defect is determined based on the energy level information obtained from the characteristic wavelengths in the ionization spectrum that meet the preset conditions, and the mapping relationship between the energy level information and the types of electronic point defects.

8. The detection method according to claim 4, characterized in that, When the number of electronic point defects in the sub-region is determined to be 1 based on the time spectrum or the power spectrum, determining the threshold wavelength based on the ionization spectrum includes: Determine multiple ionization spectra of fluorescent probe point defects corresponding to the sub-region; For any wavelength within the first range, the jump amplitude at that wavelength is obtained in multiple ionization spectra; The jump probability of the fluorescent probe point defect at any wavelength is obtained based on the jump amplitude of multiple ionization spectra at any wavelength. The transition probability spectrum is obtained based on the transition probabilities of all wavelengths within the first range; The threshold wavelength is determined based on the jump probability spectrum.

9. The detection method according to claim 8, characterized in that, For a target sub-region containing electronic point defects and having a number of electronic point defects not equal to 1, after determining the types of electronic point defects in the target sub-region, the detection method further includes: The target sub-region is irradiated with a fourth ionizing light to obtain the total jump amplitude of the local electric field of the fluorescent probe point defect corresponding to the target sub-region after being irradiated with the fourth ionizing light; the wavelength of the fourth ionizing light is the wavelength that causes the target type of electronic point defect in the target sub-region to undergo single-photon ionization. The unit jump amplitude of the fluorescent probe point defect corresponding to the target sub-region is obtained when a single electronic point defect of the target type is located at the center of the target sub-region; The number and concentration of electronic point defects of the target type in the target sub-region are determined based on the total jump amplitude and the unit jump amplitude.

10. The detection method according to claim 1, characterized in that, The sample to be tested is a wide bandgap semiconductor.

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