Quantitative analysis method for migration characteristics of indium component in epitaxial wafer

Abstract

The invention belongs to the technical field of reliability analysis of devices, and particularly relates to a quantitative analysis method for migration characteristics of an indium component in an epitaxial wafer. Comprising the following steps: providing epitaxial wafers with consistent initial characteristics, and carrying out uniform cleavage; taking one small block as a reference sample, and performing external disturbance treatment on other small blocks; the method comprises the following steps: respectively carrying out non-destructive structure characterization treatment on a reference sample and a sample subjected to external disturbance treatment, including high-resolution X-ray diffraction test, photoluminescence and cathode fluorescence combined test and time-resolved photoluminescence spectrum measurement; comprising high-resolution transmission electron microscope and EDS energy spectrum combined imaging and secondary ion mass spectrum; finally, FP lasers are prepared respectively, and electrical characterization processing is carried out. And quantitatively analyzing the influence of indium component migration on the electrical properties of the FP laser according to the result. The method has the advantages that the migration of indium atoms is analyzed according to a method for changing the microstructure in the quantum well and changing the dynamic behavior of a carrier.

Description

Technical Field

[0001] This invention belongs to the field of device reliability analysis technology, and in particular relates to a quantitative analysis method for the migration characteristics of indium components in epitaxial wafers. Background Technology

[0002] Indium atoms are a crucial component of the quantum well in the active region of semiconductor laser chips. The introduction of indium can significantly alter the bandgap of semiconductor materials. For example, in GaAs-based semiconductor lasers, adjusting the indium composition can extend the emission wavelength from near-infrared (900 nm) to above 1.3 μm, covering the optical communication window. In GaN-based semiconductor lasers, adjusting the indium composition can extend the emission wavelength from the ultraviolet band (365 nm) to the blue-green light band (530 nm), supporting blue lasers and LED display technologies. Furthermore, the introduction of indium can achieve appropriate compressive strain (such as in high-indium-content InGaN), improving hole mobility and enhancing the radiative recombination efficiency of the laser.

[0003] However, due to the high reactivity and mobility of indium atoms, long-wavelength semiconductor lasers containing indium atoms often experience current or voltage overloads, current surges, and thermal overloads after long-term operation. These thermal effects accumulate a large amount of heat inside the laser, causing excessively high local temperatures in the active region. Driven by high temperature and high carrier concentration, indium atoms become unstable and form defects. The interaction between indium atoms and point defects (such as vacancies) causes potential fluctuations, promotes carrier localization, and forms non-radiative recombination centers, directly affecting device lifetime. Indium segregation is one of the main causes of laser degradation, and studying its stability is crucial for lasers used in optical modules, big data, cloud computing, optical interconnects, sensing and detection, laser medicine, and industrial processing.

[0004] The impact of indium migration on laser performance: Indium migration in the active region narrows the quantum well bandgap, shifting the output wavelength towards longer wavelengths and reducing wavelength stability; it increases the threshold current because indium atom migration blurs the quantum well interface, weakens carrier confinement, and exacerbates carrier leakage, leading to increased laser start-up current and power consumption; it also worsens the optical confinement factor, resulting in more photon escape and decreased conversion efficiency and output power. In high-temperature positive feedback loops, indium atom migration leads to increased defects, accelerating device performance degradation over time, shortening lifetime, and reducing reliability. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a quantitative analysis method for the migration characteristics of indium components in epitaxial wafers.

[0006] The present invention aims to provide a quantitative analysis method for the migration characteristics of indium components in epitaxial wafers, comprising the following steps: S1. Provide at least two epitaxial wafers with identical initial characteristics and perform uniform cleaving; after cleaving, use one of the small pieces as a reference sample, and process the other small pieces under different external perturbation conditions respectively; S2. Non-destructive structural characterization was performed on the reference sample and the sample subjected to external perturbation, including high-resolution X-ray diffraction, combined photoluminescence and cathodoluminescence testing, and time-resolved photoluminescence spectroscopy measurement: S3. Destructive structural characterization processes were performed on the reference sample and the sample subjected to external perturbation, including high-resolution transmission electron microscopy combined with energy-dispersive X-ray spectroscopy imaging and secondary ion mass spectrometry. S4. Fabricate Fabry-Perot lasers from the reference sample and the sample after external perturbation, and perform electrical characterization. Based on the electrical characterization results, quantitatively analyze the influence of indium component migration on the electrical performance of the Fabry-Perot laser.

[0007] Preferably, the initial characteristics include doping concentration, lattice quality, and / or emission spectrum; The epitaxial wafers with consistent initial characteristics were grown by metal-organic chemical vapor deposition and subjected to capacitance-voltage testing, X-ray diffraction testing, and photoluminescence imaging testing.

[0008] Preferably, the external disturbance conditions include current density, electron beam excitation energy, excitation light power density, local temperature, mechanical stress, chemical environment, magnetic field and / or annealing conditions.

[0009] Preferably, the external disturbance condition is: current density of 10~500 A / cm². 2 The indium atom migration process; electron beam excitation conditions: 0–40 keV; excitation light power density: 10–200 W / cm² 2 .

[0010] Preferably, step S2 specifically includes the following sub-steps: S21. High-resolution X-ray diffraction test: The peak position shift Δ2θ of the multi-level satellite peaks was measured, and the interplanar spacing change was calculated according to the Bragg equation to obtain the initial indium composition loss Δx. In,XRD ; S22. Combined test of photoluminescence and cathodoluminescence: S221. Record the quantum well emission peak position λ by global photoluminescence scanning. PL Using the peak redshift Δλ before and after the external perturbation as input, the correspondence between the indium composition and the band structure of the quantum well is calculated using the Kronnick-Panna model theoretical formula, and the peak redshift Δλ is converted into the net change in global indium composition Δx. In,PL ; S222. Using cathodoluminescence nanoimaging, indium-related spectral information is extracted, and the indium concentration change in the local region is calculated; the difference in indium concentration before and after the perturbation is compared to obtain the net change in local indium composition Δx. In,CL ; S23. Time-resolved photoluminescence spectroscopy measurement and multi-dimensional analysis: S231. The fluorescence intensity of the sample is measured using time-resolved photoluminescence spectroscopy. Data on the decay of fluorescence intensity over time is collected and decay curves are obtained. The fluorescence lifetime parameters of the sample are then extracted. S232. Analyze the changes in fluorescence lifetime to determine the effect of external perturbations on the lattice quality and defect state density of the material; evaluate the effect of nonradiative recombination centers on fluorescence lifetime by comparing the fluorescence kinetics before and after annealing. S233. Based on fluorescence lifetime variation data under different perturbation conditions, infer the kinetic process of indium segregation formation and how the kinetic process affects the electronic structure of the material.

[0011] Preferably, in step S21, the Bragg equation is: 2d sinθ=nλ; where d is the interplanar spacing of the sample, θ is the angle between the incident ray, the reflected ray and the reflecting mirror, λ is the wavelength, and n is the reflection order. The change in interplanar spacing is Δd, where Δd = d - d0; and d represents the interplanar spacing of the sample to be tested, while d0 represents the interplanar spacing of the untreated sample. Initial indium component loss Δx In,XRD =Δd / d0×100%.

[0012] Preferably, in step S232, the effect of external perturbation on the lattice quality and defect state density of the material includes: if the fluorescence lifetime is shortened or the proportion of nonradiative recombination lifetime is increased, it is determined that the external perturbation leads to a decrease in the lattice quality and an increase in the defect state density of the material; nonradiative recombination centers include dislocation lines and clusters.

[0013] Preferably, step S3 specifically includes the following sub-steps: S31. The cross-sectional sample was imaged by combining high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy, and the size distribution of indium component clusters or phase separation at the quantum well / barrier interface was measured and statistically analyzed. S32. The longitudinal indium component concentration distribution of the laser epitaxial wafer before and after external perturbation is obtained by secondary ion mass spectrometry, and the longitudinal migration of the indium component is obtained.

[0014] Preferably, the size distribution in step S31 includes equivalent diameter, areal density, and volume fraction; The quantitative indicators of the longitudinal migration of the indium component in step S32 include the indium longitudinal diffusion length L. In With respect to the steepness of the interface Δz.

[0015] Preferably, the electrical characterization process in step S4 includes PIV characteristic curve analysis, capacitance-voltage measurement, and electroluminescence spectroscopy measurement; specifically including: S41. Perform PIV characteristic curve analysis on the Fabry-Perot laser to obtain the leakage current change caused by indium component migration and the barrier height change; S42. Capacitance-voltage measurements were performed on the Fabry-Perot laser to obtain the change in carrier concentration distribution caused by indium migration and to detect the interface states caused by indium migration; S43. Perform electroluminescence spectroscopy measurements on the Fabry-Perot laser, detect the changes in electroluminescence wavelength and intensity of the Fabry-Perot laser in real time during operation, and analyze the influence of indium migration on the device's luminous efficiency, spectral stability, and luminous uniformity.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: Existing technologies only perform macroscopic analyses of laser chip failures, progressing layer by layer from the outside in, including physical defect inspection, optoelectronic performance testing, cavity surface optical field distribution testing, scanning electron microscopy inspection, and internal solder quality analysis. They do not provide detailed methods for studying the migration process of indium atoms and the defect formation process by examining changes in the microstructure and carrier dynamics within the quantum well. The quantitative analysis method for indium composition migration characteristics in epitaxial wafers provided by this invention plays a predictive and auxiliary role in device structure design and epitaxial growth condition optimization, providing support for improving laser performance and reliability. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the XRD changes caused by indium component migration in the quantitative analysis method for the migration characteristics of indium component in epitaxial wafers described in the embodiments of the present invention; Figure 2 Simulation of the increase in indium composition near dark spots in the quantitative analysis method for the migration characteristics of indium composition in epitaxial wafers described in the embodiments of the present invention; Figure 3This is a schematic diagram illustrating the lifetime variation of carriers under different external perturbation conditions in the quantitative analysis method for the migration characteristics of indium components in epitaxial wafers described in the embodiments of the present invention. In the figure: (a) represents the measurement results of the reference sample without external perturbation treatment; (b) represents the measurement results after treatment at 150°C for 1 hour; (c) represents the measurement results after treatment at 150°C for 2 hours; and (d) represents the measurement results after treatment at 150°C for 4 hours. Figure 4 The SIMS spectrum of the sample before external perturbation in the quantitative analysis method for the migration characteristics of indium components in epitaxial wafers described in the embodiments of the present invention; Figure 5 The SIMS spectrum of the sample after external perturbation in the quantitative analysis method for the migration characteristics of indium components in the epitaxial wafer described in the embodiments of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] This invention provides a quantitative analysis method for the migration characteristics of indium components in epitaxial wafers, specifically including the following steps: S1. Provide at least two epitaxial wafers with consistent initial properties and perform uniform cleaving; use one of the cleaved pieces as a reference sample (for comparison with other samples that have undergone different treatments), and treat the other cleaved pieces under different external perturbation conditions to study the effect of external perturbation conditions on the migration of indium components. Specifically, initial characteristics include doping concentration, lattice quality, and emission spectrum; Epitaxial wafers with consistent initial characteristics were grown by metal-organic chemical vapor deposition (MOCVD) and subjected to capacitance-voltage (ECV), X-ray diffraction (XRD), and photoluminescence (PL) imaging tests to ensure the quality and consistency of the epitaxial wafers. External disturbance conditions include: current density, electron beam excitation energy, excitation light power density, local temperature, mechanical stress, chemical environment, magnetic field, annealing conditions, etc.

[0023] S2. Non-destructive structural characterization processes were performed on the reference sample and the sample subjected to external perturbation. Specifically, non-destructive structural characterization processes include high-resolution X-ray diffraction (HR-XRD) testing, combined photoluminescence (PL) and cathodoluminescence (CL) testing, and time-resolved photoluminescence spectroscopy (TRPL) measurements: S21. High-resolution X-ray diffraction testing, including: measuring the peak position shift Δ2θ of multi-level satellite peaks, and calculating the interplanar spacing change Δd according to the Bragg equation to obtain the initial indium (In) composition loss Δx. In,XRD ; Bragg's equation is: 2d sinθ = nλ; where d is the interplanar spacing of the sample, θ is the angle between the incident ray, the reflected ray and the reflecting mirror, λ is the wavelength, and n is the reflection order. If the multi-order satellite peaks shift towards a larger 2θ angle, θ increases, and the corresponding interplanar spacing d decreases, indicating the introduction of atoms with radii smaller than the host atom. For example, the atomic radius of In is 1.55 Å, that of gallium (Ga) is 1.3 Å, and that of aluminum (Al) is 1.25 Å, indicating a significant reduction in the In atom content in the sample. The change in interplanar spacing Δd = d - d0; where d is the interplanar spacing of the sample to be tested, and d0 represents the interplanar spacing of the untreated sample. Initial indium (In) component loss Δx In,XRD =Δd / d0×100%; S22. Combined photoluminescence and cathodoluminescence testing, including: S221. Record the quantum well emission peak position λ by global photoluminescence scanning. PL Using the peak redshift Δλ before and after the external perturbation as input, the correspondence between the indium composition and the band structure of the quantum well is calculated using the Kronnick-Panna model theoretical formula, and the peak redshift Δλ is converted into the net change in global In composition Δx. In,PL ; The specific calculation methods include: determining the energy levels of electrons using the Kronnick-Panna model based on the width of the quantum well and the composition of the material; and calculating the change in indium composition by comparing the energy level changes before and after the perturbation. S222. Using cathodoluminescence nanoimaging, spectral information related to indium (In) is extracted, and the change in indium (In) concentration in the local region is calculated; the difference in indium (In) concentration before and after the perturbation is compared to obtain the net change in local indium composition Δx. In,CL By analyzing the changes in indium (In) distribution near defect points in the quantum well, the diffusion mode of indium is determined. If the indium distribution changes uniformly, it indicates that the indium composition diffuses within the layers; if the indium distribution changes non-uniformly, it indicates that the indium mainly diffuses between layers. Through this step, nanoscale spatially resolved images of the indium (In) distribution and the local net change in indium composition Δx are obtained. In,CL ; S223. Cross-validation: The net change in the global In component Δx In,PL Net change in local indium composition Δx In,CL Comparison: when the deviation is ≤ ±0.005, it is confirmed as a reliable value; otherwise, the cathodoluminescence nanoimaging result shall be used as the standard, and the global average value shall be corrected. S23. Time-resolved photoluminescence spectroscopy measurement and multi-dimensional analysis: S231. The fluorescence intensity of the sample is measured using time-resolved photoluminescence spectroscopy. Data on the decay of fluorescence intensity over time is collected and decay curves are obtained. The fluorescence lifetime parameters of the sample are then extracted. S232. Lattice quality and defect state analysis: Analyze the changes in fluorescence lifetime to determine how external perturbations affect the lattice quality and defect state density of the material; if the fluorescence lifetime is shortened or the proportion of nonradiative recombination lifetime increases (defect state trapping carriers accelerates lifetime decay), it can be determined that external perturbations lead to an increase in the defect state density and a decrease in lattice quality; by comparing the fluorescence kinetics before and after annealing, the influence of nonradiative recombination centers on fluorescence lifetime can be evaluated. Specifically, non-radiative recombination centers include dislocation lines, clusters, etc. S233. In segregation analysis: Based on fluorescence lifetime variation data under different perturbation conditions, infer the kinetic process of In segregation and how the kinetic process affects the electronic structure of the material (such as affecting carrier transport paths, changing radiative recombination efficiency, introducing impurity energy levels, etc.).

[0024] S3. Destructive structural characterization processes were performed on the reference sample and the sample subjected to external perturbation, including high-resolution transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (EDS) imaging and secondary ion mass spectrometry; specifically including: S31. The cross-sectional sample was imaged by combining high-resolution transmission electron microscopy with energy dispersive spectroscopy (HR-TEM / EDS), and the size distribution of indium component clusters or phase separation at the quantum well / barrier interface was measured and statistically analyzed. Among them, size distribution includes equivalent diameter, areal density and volume fraction, etc. S32. The longitudinal indium component concentration distribution of the laser epitaxial wafer before and after external perturbation is obtained by secondary ion mass spectrometry (SIMS), thereby obtaining the longitudinal migration of the In component; specifically, the In concentration-depth distribution curve is plotted, and the longitudinal diffusion length L of In is extracted. In The interface steepness Δz is used as a quantitative indicator of the longitudinal migration of In.

[0025] S4. The reference sample and the sample after external perturbation were respectively prepared into Fabry-Perot (FP) lasers and subjected to electrical characterization. Based on the electrical characterization results, the influence of indium component migration on the electrical performance of the FP laser was quantitatively analyzed. Specifically, electrical characterization includes PIV characteristic curve analysis, capacitance-voltage measurement, and electroluminescence spectroscopy measurement; specifically including: S41. Perform PIV characteristic curve analysis on the FP laser to obtain the leakage current change caused by indium component migration and the barrier height change; S42. Capacitance-voltage (CV) measurements are performed on the FP laser to obtain the changes in carrier concentration distribution caused by indium migration and to detect the interface states caused by In migration; S43. Perform electroluminescence (EL) spectroscopy measurements on FP lasers, detect the changes in electroluminescence wavelength and intensity of FP lasers in real time during operation, analyze the influence of indium migration on device luminous efficiency, spectral stability and luminous uniformity; evaluate the optical quality of materials and luminous characteristics of devices by measuring the peak position, intensity and full width at half maximum (FWHM) of the EL spectrum. Based on the electrical characterization results, the impact of indium migration on the overall performance of FP lasers was evaluated, including luminous efficiency, threshold current, and operational stability.

[0026] Example 1 This embodiment takes InGaAs strained quantum wells as an example to provide a quantitative analysis method for the migration characteristics of indium composition in epitaxial wafers, specifically including the following steps: S1. Provide at least two epitaxial wafers with consistent initial properties and perform uniform cleaving; use one of the cleaved pieces as a reference sample (for comparison with other samples that have undergone different treatments), and treat the other cleaved pieces under different external perturbation conditions to study the effect of external perturbation conditions on the migration of indium components. The controllability conditions for the influence of external disturbances on defect formation are: current pumping conditions of 10~500 A / cm. 2 The migration process of In atoms under the following conditions; electron beam excitation conditions are approximately 0–40 keV; excitation light power density is 10–200 W / cm². 2 When the local temperature rises to 130℃, strong light absorption begins to form in the active region; when the local temperature reaches 300℃, thermal escape occurs; when the local temperature rises to 1200℃, local melting begins to occur. High-temperature aging tests are performed on the laser epitaxial wafer and device, and the tests are interrupted periodically. The In atom migration process is characterized by the following steps.

[0027] S2. Non-destructive structural characterization was performed on the reference sample and the sample subjected to external perturbation, including high-resolution X-ray diffraction (HR-XRD) testing, photoluminescence (PL) and cathodoluminescence (CL) combined testing; as detailed below: S21. High-resolution X-ray diffraction testing, including: measuring the peak position shift Δ2θ of multi-level satellite peaks, and calculating the interplanar spacing change Δd according to the Bragg equation to obtain the initial indium (In) composition loss Δx. In,XRD ; Bragg's equation is: 2d sinθ = nλ; where d is the interplanar spacing of the sample, θ is the angle between the incident ray, the reflected ray and the reflecting mirror, λ is the wavelength, and n is the reflection order. If the multi-order satellite peaks shift towards a larger 2θ angle, θ increases, and the corresponding interplanar spacing d decreases, indicating the introduction of atoms with radii smaller than the host atom. For example, the atomic radius of In is 1.55 Å, that of gallium (Ga) is 1.3 Å, and that of aluminum (Al) is 1.25 Å, indicating a significant reduction in the In atom content in the sample. The change in interplanar spacing Δd = d - d0; where d is the interplanar spacing of the sample to be tested, and d0 represents the interplanar spacing of the untreated sample. Initial indium (In) component loss Δx In,XRD =Δd / d0×100%; Figure 1 High-resolution X-ray diffraction (HR-XRD) patterns are presented, with the horizontal axis representing the diffraction angle 2θ and the vertical axis representing the diffraction intensity (in counts). The figures show XRD patterns under different processing conditions, with different colored curves representing samples under different external perturbation conditions. As the processing conditions change, the positions (2θ values) of the diffraction peaks shift. In particular, when indium atoms migrate, the diffraction peaks shift towards larger 2θ angles. By comparing the spectral results, the effects of different processing conditions on indium atom migration and crystal structure can be analyzed.

[0028] S22. Combined test of photoluminescence and cathodoluminescence: S221. Record the quantum well emission peak position λ by global photoluminescence scanning. PL Using the peak redshift Δλ before and after the external perturbation as input, the correspondence between the indium composition and the band structure of the quantum well is calculated using the Kronnick-Panna model theoretical formula, and the peak redshift Δλ is converted into the net change in global In composition Δx. In,PL The calculation method is as follows: based on the width of the quantum well and the composition of the material, the energy levels of the electrons are determined using the Kronnick-Panna model; by comparing the changes in energy levels before and after the perturbation, the change in indium composition is calculated. S222. Using cathodoluminescence nanoimaging, spectral information related to indium (In) is extracted, and the change in indium (In) concentration in the local region is calculated; the difference in indium (In) concentration before and after the perturbation is compared to obtain the net change in local indium composition Δx. In,CL By analyzing the changes in indium (In) distribution near defect points in the quantum well, the diffusion mode of indium is determined. If the indium distribution changes uniformly, it indicates that the indium composition diffuses within the layers; if the indium distribution changes non-uniformly, it indicates that the indium mainly diffuses between layers. Through this step, nanoscale spatially resolved images of the indium (In) distribution and the local net change in indium composition Δx are obtained.In,CL ; Figure 2 The results of cathodoluminescence (CL) imaging are shown, which is a simulated diagram of the increase in indium atoms near the dark spot (the center point corresponds to the point of maximum segregation); the color changes in the figure represent different indium concentrations.

[0029] Brief Description of the Principle: To quantitatively analyze the changes in In atomic composition, the band gap energy formula is used to estimate the changes in various components within the quantum well layer. In this step, non-destructive photoluminescence (PL) and cathodoluminescence (CL) techniques are used to study the optical properties of the epitaxial structure before and after external perturbation, monitoring the redshift phenomenon of the emission peak to obtain the changes in In composition. The Kronnick-Panna model theory is used to calculate the correspondence between the In composition and the band structure of the quantum well. CL is used to achieve nanoscale and spatially resolved In distribution imaging to obtain the relationship between local In concentration and luminescence characteristics. The changes in In distribution near defect points in the quantum well are analyzed. If the diffusion is uniform, it proves that the In composition is diffused within the layer; if the diffusion is non-uniform, it proves that In mainly diffuses between layers.

[0030] S23. Time-resolved photoluminescence spectroscopy measurement and multi-dimensional analysis, including: S231. The fluorescence intensity of the sample is measured using time-resolved photoluminescence spectroscopy. Data on the decay of fluorescence intensity over time is collected and decay curves are obtained. The fluorescence lifetime parameters of the sample are then extracted. S232. Lattice Quality and Defect State Analysis: Analyze changes in fluorescence lifetime to determine how external perturbations affect the lattice quality and defect state density of the material. If the lifetime is shortened or the proportion of nonradiative recombination lifetime increases (defect states trap carriers, accelerating lifetime decay), it can be determined that external perturbations lead to an increase in the defect state density and a decrease in lattice quality. By comparing the fluorescence kinetics before and after annealing, the influence of nonradiative recombination centers on fluorescence lifetime can be evaluated. Nonradiative recombination centers include dislocation lines, clusters, etc. S233. In segregation analysis: Based on fluorescence lifetime variation data under different perturbation conditions, combined with nonradiative recombination mechanisms, the dynamic process of In segregation formation is inferred, and how this dynamic process (such as In atom aggregation to form clusters) affects the electronic structure of the material (such as affecting carrier transport paths, changing radiative recombination efficiency, introducing impurity energy levels, etc.).

[0031] The lifetime variation results of carriers under different external disturbance conditions are as follows: Figure 3As shown, with the increase of annealing time (from 1 hour to 4 hours), the fluorescence lifetime generally shows a prolonged trend. The lattice changes caused by indium atom migration are more obvious, which can be seen from the red shift of the fluorescence peak position and the extension of the fluorescence lifetime. After annealing, the fluorescence peak position shifts towards longer wavelengths, i.e., a red shift occurs. The fluorescence intensity increases, and the color scale changes from blue to red, indicating improved luminous efficiency. This may be because annealing improves the crystal quality of the material and reduces the defect state density. The results show that annealing has a positive impact on material properties, manifested in the extension of fluorescence lifetime and the increase in fluorescence intensity, which helps to improve the performance of optoelectronic devices.

[0032] Brief Principle: In semiconductor epitaxial layers, In segregation in the active layer leads to increased crystal quality and defect state density, directly affecting the electron-hole recombination rate. A key manifestation of this is the change in electron-hole recombination fluorescence lifetime. When the defect state density increases, or when fluctuations in the composition distribution cause localization or fluctuations in the lattice's periodic potential field, electrons and holes are captured by certain localized defects or states, resulting in a decay of the electron-hole or exciton fluorescence lifetime. Therefore, by comparing fluorescence kinetics, we can reflect the state changes of the active layer and adjacent barrier layer after annealing related to photoradiative processes. This step uses time-resolved photoluminescence spectroscopy to study the relationship between carrier lifetime and external perturbations, exploring changes in lattice quality. The effective fluorescence lifetime of a quantum well is mainly determined by the radiative and non-radiative recombination lifetimes of carriers. The non-radiative recombination lifetime is mainly affected by non-radiative recombination centers such as dislocation lines and clusters, thus allowing us to deduce the kinetic processes of In segregation formation.

[0033] S3. Perform destructive structural characterization on the reference sample and the sample subjected to external perturbation; specifically including: S31. The cross-sectional sample was imaged by combining high-resolution transmission electron microscopy with energy dispersive spectroscopy (HR-TEM / EDS), and the size distribution of indium component clusters or phase separation at the quantum well / barrier interface was measured and statistically analyzed; wherein, the size distribution includes equivalent diameter, areal density and volume fraction, etc. S32. The longitudinal indium component concentration distribution of the laser epitaxial wafer before and after external perturbation is obtained by secondary ion mass spectrometry (SIMS), thereby obtaining the longitudinal migration of the In component; specifically, the In concentration-depth distribution curve is plotted, and the longitudinal diffusion length L of In is extracted. In Interface steepness Δz is used as a quantitative indicator of In longitudinal migration; The SIMS spectra of the epitaxial wafer before and after the perturbation are as follows: Figures 4-5As shown in the figure, the longitudinal distribution of indium concentration before and after external perturbation reveals the potential impact of indium atom migration and distribution changes on the material structure and properties. It can be seen that the perturbed sample exhibits a significant change in indium concentration distribution, particularly between the quantum well and barrier regions; the indium concentration distribution curve of the perturbed sample is wider, indicating longitudinal diffusion of indium atoms; the interface steepness Δz (Δz is the longitudinal distance corresponding to the indium component concentration at the quantum well / barrier interface decreasing from 90% to 10%) decreases after perturbation, indicating that the indium distribution at the interface becomes more uniform; by comparing the 1 / e decay depth (i.e., the depth when the concentration decreases to 1 / e of the initial value) before and after perturbation, the longitudinal diffusion length L of indium can be calculated. In .

[0034] S4. Under the same preparation conditions, the reference sample and the sample after external perturbation were respectively prepared into Fabry-Perot (FP) lasers and subjected to electrical characterization. Based on the electrical characterization results, the influence of indium component migration on the electrical performance of the FP laser was quantitatively analyzed, including luminous efficiency, threshold current, and operating stability. Specifically, this included: S41. Perform PIV characteristic curve analysis on the FP laser to obtain the leakage current change caused by indium component migration and the barrier height change; Indium component migration leads to increased nonradiative recombination, and the internal quantum well efficiency η i Significant decrease; experimental data show that after high-temperature aging (accelerated indium migration), the slope efficiency of lasers decreases by 20% to 50% or even more. For example, the slope efficiency of a new device is 0.4 W / A, which may drop to 0.25 W / A after aging, a decrease of 37.5%.

[0035] S42. Capacitance-voltage (CV) measurements are performed on the FP laser to obtain the changes in carrier concentration distribution caused by indium migration and to detect the interface states caused by In migration; The increase in threshold current is one of the most significant electrical characteristics of indium component migration, and it is directly related to changes in carrier concentration distribution and interface states. In aging experiments, the rate of increase in threshold current is a key parameter for measuring the device degradation rate. Typically, when the threshold current increases to 1.5 times its initial value (i.e., an increase of 50%), the device is considered to have reached the end of its lifespan. For degradation dominated by indium migration, this degradation process can be very rapid, with the threshold current reaching this critical value after several hundred to several thousand hours of accelerated aging due to external disturbances.

[0036] S43. Perform electroluminescence (EL) spectroscopy measurements on FP lasers, detect the changes in electroluminescence wavelength and intensity of FP lasers in real time during operation, analyze the influence of indium migration on device luminous efficiency, spectral stability and luminous uniformity; evaluate the optical quality of materials and luminous characteristics of devices by measuring the peak position, intensity and full width at half maximum (FWHM) of the EL spectrum.

[0037] In the method of this invention, non-destructive characterization provides rapid and non-destructive preliminary analysis, destructive characterization provides in-depth microstructural information, and electrical characterization directly links structural changes with device performance. Through multi-step and multi-angle analysis methods, the influence of indium component migration on material and device performance can be fully understood, thereby providing a scientific basis for material optimization and device design. The advantages are: (1) It provides a comprehensive analysis method: Combining non-destructive and destructive structural characterization techniques, including high-resolution X-ray diffraction, photoluminescence, cathodoluminescence, time-resolved photoluminescence spectroscopy, high-resolution transmission electron microscopy, and secondary ion mass spectrometry, it provides a comprehensive analysis framework. (2) Quantitative evaluation: Through precise quantitative analysis (such as lattice constant changes, fluorescence lifetime, carrier concentration distribution, indium concentration distribution, etc.), this method can accurately evaluate the degree and influence of indium component migration, providing data support for material and device performance optimization. (3) High-resolution imaging: Using cathodoluminescence nanoimaging technology, nanoscale spatial resolution indium distribution imaging is achieved, which helps to understand the microscopic distribution and diffusion behavior of indium in quantum wells. (4) A deeper understanding of the impact of indium component migration on material properties can help guide the optimization of material growth and device design, thereby improving the performance and reliability of optoelectronic devices.

[0038] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0039] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for quantitatively analyzing indium composition migration characteristics in an epitaxial wafer, characterized by: The method comprises the following steps: S1. providing at least two pieces of epitaxial wafer with uniform initial characteristics, and uniformly cleaving; after cleaving, taking one piece as a reference sample, and treating the other pieces under different external disturbance conditions respectively; S2. performing non-destructive structural characterization on the reference sample and the samples treated under external disturbance respectively, including high-resolution X-ray diffraction test, photoluminescence and cathodoluminescence combined test, and time-resolved photoluminescence spectrum measurement: S3. performing destructive structural characterization on the reference sample and the samples treated under external disturbance respectively, including high-resolution transmission electron microscopy combined with energy dispersive X-ray spectroscopy imaging and secondary ion mass spectrometry; S4. preparing the reference sample and the samples treated under external disturbance into Fabry-Perot lasers respectively, and performing electrical characterization; and quantitatively analyzing the influence of indium component migration on the electrical performance of the Fabry-Perot lasers according to the electrical characterization results.

2. The method for quantitatively analyzing indium component migration characteristics in an epitaxial wafer according to claim 1, characterized by: The initial characteristics include doping concentration, lattice quality or / and luminescence spectrum; The epitaxial wafer with uniform initial characteristics is obtained by metal organic chemical vapor deposition, and is subjected to capacitance voltage test, X-ray diffraction test and photoluminescence imaging test.

3. The method according to claim 1, wherein the method is characterized by: The external disturbance conditions include current density, energy of electron beam excitation, excitation light power density, local temperature, mechanical stress, chemical environment, magnetic field or / and annealing conditions.

4. The method according to claim 3, wherein the method is characterized by: The external perturbation condition is: current density is 10~500 A / cm 2 The indium atom migration process under the electron beam excitation condition is 0~40 keV; the excitation light power density is 10~200 W / cm 2 .

5. The method according to claim 1, wherein the method is characterized by: The step S2 specifically comprises the following sub-steps: S21. High-resolution X-ray diffraction test: measure the peak position shift Δ2θ of the multi-order satellite peaks, and convert the interplanar spacing change value according to the Bragg equation to obtain the initial indium component loss Δx In,XRD ; S22. photoluminescence and cathodoluminescence combined test: S221. Record the quantum well light emitting peak position λ by the photoluminescence global scanning PL ; take the peak position red shift amount Δλ before and after the external disturbance as the input, calculate the corresponding relationship between the indium composition and the energy band structure of the quantum well by the theoretical calculation formula of the Kronig-Penner model, and convert the peak position red shift amount Δλ into the net change amount Δx of the global indium composition In,PL ; S222. Extract the spectral information related to indium by cathodoluminescence nanoscopy, calculate the local change of indium concentration; compare the difference of indium concentration before and after the perturbation, and obtain the net change of local indium component Δx In,CL ; S23. time-resolved photoluminescence spectrum measurement and multi-dimensional analysis: S231. measuring the fluorescence intensity of the sample by using time-resolved photoluminescence spectrum technology, collecting the data of the decay of the fluorescence intensity with time and obtaining the decay curve, and extracting the fluorescence lifetime parameter of the sample; S232. analyzing the change of the fluorescence lifetime, determining the influence of the external disturbance on the lattice quality and defect state density of the material; and evaluating the influence of the non-radiation recombination center on the fluorescence lifetime by comparing the fluorescence kinetic process before and after annealing; S233. based on the fluorescence lifetime change data under different disturbance conditions, deducing the kinetic process of indium segregation and how the kinetic process affects the electronic structure of the material.

6. The method according to claim 5, wherein the method is characterized by: In the step S21, the Bragg equation is: 2d sinθ=nλ; in the equation, d is the interplanar spacing of the sample, θ is the included angle between the incident line, the reflected line and the mirror surface, λ is the wavelength, and n is the reflection order; The interplanar spacing change value is Δd, and Δd=d-d0; wherein d is the interplanar spacing of the sample to be measured, and d0 represents the interplanar spacing of the untreated sample; Initial indium component loss amount Δx In,XRD = Δd / d0 x 100%.

7. The method according to claim 5, wherein the method is characterized by: In the step S232, the influence of the external disturbance on the lattice quality and defect state density of the material includes: if the fluorescence lifetime is shortened or the proportion of the non-radiation recombination lifetime is increased, it is judged that the external disturbance causes the lattice quality of the material to decrease and the defect state density to increase; the non-radiation recombination center includes dislocation lines and clusters.

8. The method according to claim 1, wherein the method is characterized by: The step S3 specifically comprises the following sub-steps: S31. imaging the cross-section sample by high-resolution transmission electron microscopy combined with energy dispersive X-ray spectroscopy, measuring and statistically quantifying the size distribution of indium component clusters or phase separation at the quantum well / potential barrier interface; S32. Obtain the longitudinal indium composition distribution of the epitaxial wafer before and after the external perturbation by secondary ion mass spectroscopy, and obtain the longitudinal migration of the indium composition.

9. The method according to claim 8, wherein the method is characterized by: The size distribution of the step S31 includes the equivalent diameter, the area density and the volume fraction; The quantitative index of the longitudinal migration of the indium component in the step S32 includes an indium longitudinal diffusion length L In and the interface steepness Δz.

10. The method of claim 1, wherein the method is characterized by: The electrical characterization process of the step S4 includes PIV characteristic curve analysis, capacitance-voltage measurement and electroluminescence spectrum measurement; specifically including: S41. Perform PIV characteristic curve analysis on the Fabry-Perot laser to obtain the change of the leakage current caused by the indium composition migration, and obtain the change of the barrier height; S42. Perform capacitance-voltage measurement on the Fabry-Perot laser to obtain the change of the carrier concentration distribution caused by the indium composition migration, and detect the interface state caused by the indium migration; S43. Perform electroluminescence spectrum measurement on the Fabry-Perot laser to detect the change of the electroluminescence wavelength and intensity of the Fabry-Perot laser in the working state in real time, and analyze the influence of the indium migration on the light-emitting efficiency, spectral stability and light-emitting uniformity of the device.

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