Method and device for non-destructive detection of subsurface atomic defects based on exciton diffusion

Abstract

This invention provides a method and apparatus for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, belonging to the field of nondestructive quantitative detection technology. By scanning transient absorption images of excitons in a device, the diffusion of excitons generated in a two-dimensional transition metal dichalcogenide layer on the two-dimensional transition metal dichalcogenide layer can be obtained. This allows for further querying the quantitative correspondence between the material type of the dielectric layer to obtain the detection results of subsurface atomic-level defects in the dielectric layer. The quantitative correspondence is a pre-established relationship between diffusion indices and the degree of subsurface atomic-level defects at the interface. This method enables the detection of subsurface atomic-level defects at the interface without stripping the capping layer or disassembling the device, and can achieve this detection even when the device structure is intact. It is suitable for reliability assessment after device packaging.

Description

Technical Field

[0001] This invention relates to the field of nondestructive quantitative detection technology, and in particular to a method and apparatus for nondestructive detection of subsurface atomic-level defects based on exciton diffusion. Background Technology

[0002] High electron mobility interfaces are a key foundation for constructing high-frequency, low-power electronic and optoelectronic devices. Two-dimensional materials (such as graphene and two-dimensional transition-metal dichalcogenides (TMDs)) and their van der Waals heterostructures can achieve multi-material coupling without introducing lattice mismatch stress, providing new device architectures for high-mobility channels, low-defect gate dielectrics, and tunable bandgap engineering. For these devices, carrier mobility is often limited by surface / interface rough scattering, interface charge traps, and Coulomb scattering caused by residual contamination. Therefore, highly flattened interfaces are required to reduce scattering and improve device uniformity.

[0003] In practical device fabrication, dry transfer and stacking assembly often result in polymer residues or environmental contaminants at the interface, forming bubbles, wrinkles, and localized residual layers, leading to decreased mobility and spatial non-uniformity of the device. To obtain interfaces with high electron mobility, previous studies have proposed methods such as contact atomic force microscopy probe sliding cleaning / polishing, which have been verified in graphene / boron nitride systems to significantly improve device uniformity and electron mobility. However, in actual device fabrication and post-processing, interface cleaning, polishing, and planarization processes are essentially frictional contact or abrasive-interface interaction processes. While these processes remove contaminants, they may also introduce atomic-level defects (such as vacancies, dislocations, or localized disorder), and these defects are often distributed in the subsurface region beneath the capping layer, making them difficult to observe directly in conventional surface characterization.

[0004] In existing technologies, scanning transmission electron microscopy (STEM) is used to detect subsurface atomic-level defects at interfaces. This process requires disassembling the device or peeling off the covering layer above the interface to be inspected to expose it, followed by inspection under a screen in the electron microscope. However, this method damages the device structure and is difficult to use for inspection when the device is intact. Summary of the Invention

[0005] This invention provides a method and apparatus for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, which solves the problem of defects that require destruction of device structure in the prior art, and can realize the detection of subsurface atomic-level defects at the interface while the device structure is intact.

[0006] This invention provides a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, comprising the following steps: The device is irradiated with pump light and spatially scanned with delayed probe light to obtain transient absorption images. The device includes a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The two-dimensional transition metal dichalcogenide layer and the dielectric layer are arranged in contact. The pump light can excite the two-dimensional transition metal dichalcogenide layer to generate excitons. Based on the transient absorption images described above, the diffusion index is calculated to obtain the target diffusion index value; The quantitative correspondence between the material type of the dielectric layer is queried to determine the degree of atomic-level defects in the subsurface layer of the interface corresponding to the target diffusion index value, thereby obtaining the detection result of the atomic-level defects in the subsurface layer of the dielectric layer. The quantitative correspondence is a pre-established correspondence between the diffusion index and the degree of atomic-level defects in the subsurface layer of the interface.

[0007] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein calculating a diffusion index to obtain a target diffusion index value based on each transient absorption image includes: Gaussian fitting was performed on the spatial distribution of excitons in the transient absorption images under different delays to obtain the standard deviation and variance. Obtain the initial variance of the pump light, and calculate the value of the diffusion variance increment based on the standard deviation and the initial variance, wherein the diffusion index includes the diffusion variance increment.

[0008] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein calculating the value of the diffusion variance increment based on the standard deviation, variance, and initial variance includes: The value of the diffusion variance increment is calculated using the following formula: = - ; in, For the diffusion variance increment, For standard deviation and variance, This represents the initial variance.

[0009] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein calculating a diffusion index to obtain a target diffusion index value based on each transient absorption image includes: Gaussian fitting was performed on the spatial distribution of excitons in the transient absorption images under different delays to obtain the standard deviation and variance. Obtain the initial variance of the pump light, and calculate the value of the diffusion coefficient based on the standard deviation and the initial variance, wherein the diffusion index includes the diffusion coefficient.

[0010] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein calculating the value of the diffusion coefficient based on the standard deviation, variance, and initial variance includes: The diffusion coefficient is calculated using the following formula: = ; in, For standard deviation and variance, Let be the initial variance, t be the delay time, and D be the diffusion coefficient.

[0011] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided. The device is a dual-gate van der Waals heterostructure device, which includes a first gate layer, a first dielectric layer, a first two-dimensional transition metal dichalcogenide layer, a second two-dimensional transition metal dichalcogenide layer, a second dielectric layer, and a second gate layer stacked sequentially. The first two-dimensional transition metal dichalcogenide layer is prepared on the interface of the first dielectric layer, and the pump light can excite the first two-dimensional transition metal dichalcogenide layer to generate excitons. The method further includes: applying a voltage / electric field of a specified intensity through the first gate layer and the second gate layer; The process of obtaining the quantitative correspondence between the material types of the dielectric layer includes: Obtain the quantitative correspondence between the material type of the dielectric layer and the voltage / electric field of a specified intensity.

[0012] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion includes the step of pre-establishing the quantitative correspondence as follows: The degree of defect in the sample was obtained by detecting subsurface atomic-level defects in the dielectric layer of the sample using scanning transmission electron microscopy. A two-dimensional transition metal dichalcogenide layer is prepared on the interface of the sample dielectric layer to obtain the sample device. The sample device is irradiated with pump light, and a transient absorption image of the sample is obtained by spatial scanning with delayed probe light. The pump light can excite the two-dimensional transition metal dichalcogenide layer of the sample to generate excitons. Based on the transient absorption images of each sample, the diffusion index is calculated to obtain the sample diffusion index value; Establish the correspondence between the degree of sample defect and the value of the sample diffusion index; Select other sample dielectric layers to continue establishing the correspondence between defect degree and diffusion index value until a preset number of pairs of correspondence are obtained. The sample dielectric layer and the other sample dielectric layers have the same material type and the same defect type of the interface sub-surface atomic level defect. By fitting the correspondence of the preset number pairs, a quantitative correspondence is obtained for the material type of the sample dielectric layer.

[0013] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided. The sample device comprises a first sample gate layer, a first sample dielectric layer, a first sample two-dimensional transition metal dichalcogenide layer, a second sample two-dimensional transition metal dichalcogenide layer, a second sample dielectric layer, and a second sample gate layer stacked sequentially. The first sample two-dimensional transition metal dichalcogenide layer is prepared on the interface of the first sample dielectric layer, and the pump light can excite the first sample two-dimensional transition metal dichalcogenide layer to generate excitons. The method further includes: applying a voltage / electric field of a specified intensity through the first sample gate layer and the second sample gate layer; The step of fitting the correspondence of the preset number pairs to obtain the quantitative correspondence of the material type of the sample dielectric layer includes: fitting the correspondence of the preset number pairs to obtain the quantitative correspondence of the material type of the sample dielectric layer under a specified voltage / electric field.

[0014] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein the defect type of the interface subsurface atomic-level defects is one of vacancy, substitution, or disorder.

[0015] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein the material of the same dielectric layer is one of the following materials: hexagonal boron nitride, silicon dioxide, aluminum oxide, hafnium dioxide, and titanium dioxide.

[0016] According to the present invention, a method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion is provided, wherein the material of the same two-dimensional transition metal dichalcogenide layer is one of the following materials: tungsten disulfide, molybdenum diselenide, tungsten diselenide, and molybdenum disulfide.

[0017] This invention also provides a device for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, comprising the following modules: An image acquisition module is used to irradiate a device with pump light and perform spatial scanning with delayed probe light to obtain a transient absorption image. The device includes a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The two-dimensional transition metal dichalcogenide layer and the dielectric layer are arranged in contact. The pump light can excite the two-dimensional transition metal dichalcogenide layer to generate excitons. The index calculation module is used to calculate the diffusion index based on each of the transient absorption images to obtain the target diffusion index value; The result determination module is used to query the quantitative correspondence between the material type of the dielectric layer, determine the degree of atomic-level defects in the subsurface interface corresponding to the target diffusion index value, and obtain the detection result of the atomic-level defects in the subsurface interface of the dielectric layer. The quantitative correspondence is a pre-established correspondence between the diffusion index and the degree of atomic-level defects in the subsurface interface.

[0018] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion as described above.

[0019] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for non-destructive testing of subsurface atomic-level defects based on exciton diffusion as described above.

[0020] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion as described above.

[0021] The present invention provides a method and apparatus for nondestructive testing of subsurface atomic-level defects based on exciton diffusion. By scanning transient absorption images of excitons in a device, the diffusion of excitons generated in a two-dimensional transition metal dichalcogenide layer on the two-dimensional transition metal dichalcogenide layer can be obtained. This allows for further querying the quantitative correspondence between the material type of the dielectric layer to obtain the detection results of subsurface atomic-level defects at the dielectric layer interface. The quantitative correspondence is a pre-established relationship between diffusion indices and the degree of subsurface atomic-level defects at the interface. This method enables the detection of subsurface atomic-level defects at the interface without stripping the capping layer or disassembling the device, and can be performed while the device structure is intact. It is suitable for reliability assessment after device packaging. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is one of the flowcharts of the method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion provided by the present invention; Figure 2 This is a schematic diagram of a dual-gate van der Waals heterostructure device provided by the present invention. Figure 3 This is the second flowchart of the method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion provided by the present invention; Figure 4 This is one of the flowcharts illustrating the quantitative correspondence establishment method provided by the present invention; Figure 5 This is the second flowchart of the quantitative correspondence establishment method provided by the present invention; Figure 6 This is a schematic diagram illustrating the correspondence between normal load, vacancy density, and diffusion variance increment provided by the present invention. Figure 7 This is a schematic diagram illustrating the correspondence between normal load and frictional force provided by the present invention; Figure 8 This is a schematic diagram illustrating the correspondence between the friction coefficient and defects provided by the present invention; Figure 9 This is a schematic diagram of a pump light and a probe light band for exciting and detecting excitons provided by the present invention; Figure 10 The vacancy density provided by this invention is 1.52 × 10⁻⁶. 12 cm -2 Schematic diagram of transient absorption images at different time delays; Figure 11 The vacancy density provided by this invention is 9.14 × 10⁻⁶. 12 cm -2 Schematic diagram of transient absorption images at different time delays; Figure 12 for Figure 10 A representative line profile extracted along the x-direction from the mid-space mapping; Figure 13 This is a schematic diagram illustrating the correspondence between pump detection delay and transmission variance increment provided by the present invention; Figure 14 This is a schematic diagram of a quantitative correspondence provided by the present invention; Figure 15 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] Related technologies for detecting atomic-level defects at the interface surface mainly include: detection using scanning transmission electron microscopy, detection using atomic force microscopy (AFM), detection using steady-state spectral information, and detection using electrical properties. However, the detection methods in these technologies have the following drawbacks: (1) Destructive and difficult to use online: Scanning transmission electron microscopy can provide atomic resolution images, but usually requires transferring the sample to the electron microscope grid and thinning or peeling off the covering layer. It is an offline characterization method that is easy to damage the device structure and is difficult to use for large-area statistics and rapid screening when the device is intact.

[0026] (2) For AFM detection, the surface is sensitive but it is difficult to cover the subsurface layer: AFM morphology / friction mapping and other methods mainly reflect the surface roughness and surface interaction, and it is difficult to penetrate the covering layer to give the spatial distribution and quantitative density of defects such as vacancies in the subsurface layer.

[0027] (3) "Averaging" of steady-state spectral information: Raman, steady-state photoluminescence, reflection / absorption and other spectra can only provide average energy level, strain or doping information in many cases. They are limited by diffraction limit and spot size, making it difficult to distinguish the dynamic differences between local defect regions and defect-free regions. For buried defects, their optical signals will be further attenuated by the covering layer.

[0028] (4) Electrical transport / overall photoelectric testing is susceptible to contact and spatial averaging: Electrical mobility, I (current)-V (voltage), overall responsivity and other parameters are mostly device-scale quantities, which are easily affected by factors such as electrode contact, charge traps and non-uniform doping, resulting in the local dynamics dominated by defects being masked, making it difficult to locate and quantitatively invert defects.

[0029] To address at least one of the aforementioned problems, this invention provides a method and apparatus for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, which will be described below in conjunction with... Figures 1 to 15 Please provide a detailed explanation.

[0030] Figure 1 This is one of the flowcharts illustrating the method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion provided by this invention, such as... Figure 1 As shown, the method includes the following steps: Step S101: Irradiate the device with pump light and perform spatial scanning with delayed probe light to obtain transient absorption images. The device includes a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The two-dimensional transition metal dichalcogenide layer and the dielectric layer are arranged in contact. The pump light can excite the two-dimensional transition metal dichalcogenide layer to generate excitons.

[0031] The device comprises a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The interface between the dielectric layer and the two-dimensional transition metal dichalcogenide layer is the interface that requires atomic-level defect detection. In fact, during the device fabrication process, the two-dimensional transition metal dichalcogenide layer is fabricated on the interface of the dielectric layer. Atomic-level defects at the dielectric layer interface have a significant impact on the two-dimensional structure of the two-dimensional transition metal dichalcogenide layer.

[0032] The dielectric layer is an insulating layer. The material of the same dielectric layer is one of the following: hexagonal boron nitride (hBN), silicon dioxide (SiO2), aluminum oxide (Al2O3), hafnium dioxide (hfO2), or titanium dioxide (TiO2). Different dielectric layers can be made of the same or different materials. The material of the same two-dimensional transition metal dichalcogenide layer is one of the following: tungsten disulfide (WS2), molybdenum diselenide (MoSe2), or molybdenum disulfide (MoS2). Different two-dimensional transition metal dichalcogenide layers are made of different materials.

[0033] Step S102: Calculate the diffusion index to obtain the target diffusion index value based on each transient absorption image.

[0034] Two-dimensional transition metal dichalcogenide (TMD) layers generate excitons under pump light irradiation. Transient absorption images acquired using probe light can represent the exciton diffusion. Therefore, a diffusion index representing the exciton diffusion can be obtained from transient absorption images at different delays. Because the TMD layer and dielectric layer are in contact, this diffusion index can represent the diffusion of excitons generated in the TMD layer within the TMD layer. It is understood that the exciton diffusion in the TMD layer is influenced by the subsurface atomic arrangement of the dielectric layer; therefore, the diffusion index is strongly correlated with the subsurface atomic arrangement at the dielectric layer interface. Specifically, subsurface atomic-level defects in the dielectric layer generate defect energy levels, which trap excitons in the TMD layer, thus affecting the exciton diffusion distance. Therefore, the diffusion index representing the diffusion distance can be used to infer the degree of defect at the subsurface atomic level of the dielectric layer. The calculated value of the diffusion index is the target diffusion index value.

[0035] Step S103: Query the quantitative correspondence between the material type of the dielectric layer, determine the degree of atomic-level defects in the subsurface interface corresponding to the target diffusion index value, and obtain the detection result of the atomic-level defects in the subsurface interface of the dielectric layer. The quantitative correspondence is a pre-established correspondence between the diffusion index and the degree of atomic-level defects in the subsurface interface.

[0036] The same quantitative correspondence exists for the same material type, while different material types correspond to different quantitative correspondences. The quantitative correspondence is a pre-established relationship between diffusion indices and the degree of atomic-level defects in the subsurface layer of the interface. That is, in the quantitative correspondence, each value of the diffusion index corresponds to a value of the degree of atomic-level defects in the subsurface layer of the interface. The defect type of the atomic-level defects in the subsurface layer of the interface is one of vacancies, substitutions, or disorder, and their corresponding degrees of atomic-level defects in the subsurface layer of the interface can be vacancy density, substitution density, or disorder density, respectively.

[0037] After obtaining the quantitative correspondence between the material type of the dielectric layer, the degree of atomic-level defects in the subsurface layer of the interface corresponding to the target diffusion index value can be obtained from the quantitative correspondence, thus obtaining the detection result of atomic-level defects in the subsurface layer of the dielectric layer.

[0038] In two-dimensional heterostructures, excitons (electron-hole pairs) and their transport are highly sensitive to local disorder and interface coupling strength. Ultrafast pump-probe transient absorption microscopy can directly track the exciton diffusion process with femtosecond time resolution and spatial scanning, providing kinetic evidence that is difficult to obtain with traditional steady-state spectroscopy. Thus, atomic-level defects at the interface and subsurface can be detected using the diffusion index of hybrid excitons. This method is applicable to various two-dimensional heterostructure material systems and various types of defects introduced by friction / polishing. It can serve as a feedback index for optimizing interface treatment processes (such as AFM cleaning, polishing / planarization parameters) and provide a basis for defect tolerance assessment in large-scale manufacturing.

[0039] In this invention, by scanning the transient absorption image of excitons in the device, the diffusion of excitons generated in the two-dimensional transition metal dichalcogenide layer on the two-dimensional transition metal dichalcogenide layer can be obtained. This allows for further querying the quantitative correspondence between the material types of the dielectric layer, thus obtaining the detection results of atomic-level defects at the interface subsurface level of the dielectric layer. This allows for the detection of atomic-level defects at the interface subsurface level without stripping the capping layer or disassembling the device, enabling the detection of these defects even when the device structure is intact. It is suitable for reliability assessment after device packaging.

[0040] Diffusion indices can be diffusion variance increment, diffusion coefficient, or diffusion length, etc. In one possible implementation, taking diffusion variance increment as an example, in... Figure 1 Based on the illustrated embodiments, the step of calculating the diffusion index to obtain the target diffusion index value according to each of the transient absorption images includes: Step A1: Perform Gaussian fitting on the spatial distribution of excitons in the transient absorption images shown under different delays to obtain the standard deviation and variance.

[0041] At each delay time t, the spatial distribution of excitons in the transient absorption image is fitted, assuming a Gaussian distribution: ; Where I(x, t) represents the spatial distribution of excitons, x represents the position of the excitons, and t is the time delay. The standard deviation σ at this moment is obtained by fitting the data. t (corresponding to σ(t) in the formula), and then calculate the standard deviation and variance. .

[0042] Step A2: Obtain the initial variance of the pump light, and calculate the value of the diffusion variance increment based on the standard deviation and the initial variance, wherein the diffusion index includes the diffusion variance increment.

[0043] In one example, the value of the diffusion variance increment is calculated according to the following formula: = - ; in, This represents the diffusion variance increment. The standard deviation and variance are; This represents the initial variance, i.e., the standard deviation and variance at t=0.

[0044] In this embodiment of the invention, the diffusion variance increment is calculated based on the spatial distribution of excitons in transient absorption images under different delays. The diffusion variance increment is then used to represent the diffusion of excitons on a two-dimensional transition metal dichalcogenide layer. The subsurface atomic arrangement at the dielectric layer interface is strongly correlated with the diffusion of excitons, so the diffusion variance increment can be used to represent the subsurface atomic arrangement at the dielectric layer interface.

[0045] In one possible implementation, taking the diffusion index as the diffusion variance increment as an example, in... Figure 1 Based on the illustrated embodiments, the step of calculating the diffusion index to obtain the target diffusion index value according to each of the transient absorption images includes: Step B1: Perform Gaussian fitting on the spatial distribution of excitons in the transient absorption images shown under different delays to obtain the standard deviation and variance.

[0046] Step B2: Obtain the initial variance of the pump light, and calculate the value of the diffusion coefficient based on the standard deviation and the initial variance, wherein the diffusion index includes the diffusion coefficient.

[0047] In one example, the diffusion coefficient is calculated using the following formula: = ; in, For standard deviation and variance, Let be the initial variance, t be the delay time, and D be the diffusion coefficient.

[0048] In this embodiment of the invention, the diffusion coefficient is calculated based on the spatial distribution of excitons in transient absorption images under different delays. The diffusion coefficient is then used to represent the diffusion of excitons on a two-dimensional transition metal dichalcogenide layer. The subsurface atomic arrangement at the dielectric layer interface is strongly correlated with the diffusion of excitons, so the diffusion coefficient can be used to represent the subsurface atomic arrangement at the dielectric layer interface.

[0049] This invention also supports in-circuit testing of the device (testing while the device is in operation). In one possible implementation, the device is a dual-gate van der Waals heterostructure device, see [link to relevant documentation]. Figure 2The dual-gate van der Waals heterostructure device comprises a first gate layer 01, a first dielectric layer 02, a first two-dimensional transition metal dichalcogenide layer 03, a second two-dimensional transition metal dichalcogenide layer 04, a second dielectric layer 05, and a second gate layer 06 stacked sequentially. The first two-dimensional transition metal dichalcogenide layer 03 is fabricated on the interface of the first dielectric layer 04, and the pump light can excite the first two-dimensional transition metal dichalcogenide layer 03 to generate excitons.

[0050] exist Figure 1 Based on the illustrated embodiments, see also Figure 3 The method further includes step S301, applying a voltage / electric field of a specified intensity through the first gate layer and the second gate layer.

[0051] Step S103, querying the quantitative correspondence of the material type of the dielectric layer to determine the degree of atomic-level defects in the subsurface layer of the interface corresponding to the target diffusion index value, and obtaining the detection result of atomic-level defects in the subsurface layer of the dielectric layer, includes: Step S1031, querying the quantitative correspondence of the material type of the dielectric layer under a specified voltage / electric field to determine the degree of atomic-level defects in the subsurface layer of the interface corresponding to the target diffusion index value, and obtaining the detection result of atomic-level defects in the subsurface layer of the dielectric layer.

[0052] The pump light needs to be able to excite the first two-dimensional transition metal dichalcogenide layer to generate excitons. In one example, the pump light cannot excite the second two-dimensional transition metal dichalcogenide layer to generate excitons, thereby eliminating the influence of the second two-dimensional transition metal dichalcogenide layer and further improving the accuracy of detection.

[0053] The voltage / electric field of a specified intensity is the operating voltage / electric field of the dual-gate van der Waals heterostructure device. The quantitative correspondence at this point is the quantitative correspondence between the material type and the voltage / electric field parameters. The correspondence between the diffusion index and the degree of subsurface atomic-level defects at the interface under a specified voltage / electric field can be pre-measured to obtain the quantitative correspondence of the material type under the specified voltage / electric field.

[0054] In this embodiment of the invention, atomic-level defects at the subsurface interface of the dielectric layer can be detected when the dual-gate van der Waals heterostructure device is in operation, thus realizing online detection in the working state.

[0055] The following describes the method for establishing quantitative correspondences. In one possible implementation, see [link to implementation details]. Figure 4 Methods for establishing quantitative correspondences include: Step S401: Use a scanning transmission electron microscope to detect the subsurface atomic-level defects at the interface of the dielectric layer of the sample to obtain the degree of sample defects.

[0056] In this step, a two-dimensional transition metal dichalcogenide layer has not yet been prepared on the interface of the sample dielectric layer. Therefore, scanning transmission electron microscopy can be used to directly detect the subsurface atomic-level defects at the interface of the sample dielectric layer, thereby obtaining the degree of sample defects. The defect type of the subsurface atomic-level defects at the interface of the sample dielectric layer is one of vacancies, substitutions, or disorder. In one example, defects can be added to the sample dielectric layer artificially.

[0057] Step S402: Prepare a two-dimensional transition metal dichalcogenide layer on the interface of the sample dielectric layer to obtain the sample device.

[0058] Step S403: Irradiate the sample device with pump light and perform spatial scanning with delayed probe light to obtain a transient absorption image of the sample, wherein the pump light can excite the sample's two-dimensional transition metal dichalcogenide layer to generate excitons.

[0059] Step S404: Calculate the diffusion index based on the transient absorption images of each sample to obtain the sample diffusion index value.

[0060] The calculation process for the sample diffusion index value can be found in the calculation process for the target diffusion index value in the above embodiments, and will not be repeated here.

[0061] Step S405: Establish the correspondence between the degree of sample defect and the sample diffusion index value.

[0062] In one example, different degrees of sample defects can be set at different locations on the surface of the sample dielectric layer, thereby establishing a correspondence between multiple sets of sample defect degrees and sample diffusion index values ​​through a single measurement.

[0063] Step S406: Select other sample dielectric layers to continue establishing the correspondence between defect degree and diffusion index value until a preset number of pairs of correspondences are obtained. The sample dielectric layer and the other sample dielectric layers have the same material type and the same defect type of the interface subsurface atomic level defects.

[0064] In establishing the same quantitative correspondence, the selected samples have the same dielectric layer material type and the same defect type. The preset number can be customized according to the actual situation; the more preset numbers, the more accurate the obtained quantitative correspondence.

[0065] Step S407: Fit the correspondence of the preset quantity pairs to obtain the quantitative correspondence of the material type of the sample dielectric layer.

[0066] Before fitting, obviously abnormal correspondences can be filtered out to ensure the accuracy of quantitative correspondences. The fitting method here can be selected according to the actual situation, such as polynomial fitting, linear regression, nonlinear least squares, spline fitting, etc.

[0067] In this embodiment of the invention, a quantitative correspondence is established for a specified material type, which can be applied to scenarios where atomic-level defects at the subsurface interface of the dielectric layer of a device are detected non-destructively.

[0068] To achieve online detection, a voltage / electric field can be applied during the establishment of the quantitative correspondence. In one possible implementation, see [link to relevant documentation]. Figure 5 Methods for establishing quantitative correspondences include: Step S501: Use a scanning transmission electron microscope to detect the subsurface atomic-level defects at the interface of the dielectric layer of the first sample to obtain the degree of sample defects.

[0069] The first sample dielectric layer is fabricated based on the first sample gate layer. That is, one side of the first sample dielectric layer is the first sample gate layer, while the other side has not yet had the first two-dimensional transition metal dichalcogenide layer fabricated. Therefore, the subsurface atomic-level defects at the interface of the sample dielectric layer can be directly detected using scanning transmission electron microscopy, thus obtaining the degree of sample defects. The defect type of the subsurface atomic-level defects at the interface of the first sample dielectric layer is one of vacancies, substitutions, or disorder. In one example, defects can be artificially added to the first sample dielectric layer.

[0070] Step S502: Prepare a first sample two-dimensional transition metal dichalcogenide layer on the interface of the first sample dielectric layer to obtain the sample device.

[0071] A first sample two-dimensional transition metal dichalcogenide layer is fabricated on a first sample dielectric layer. A second sample two-dimensional transition metal dichalcogenide layer is fabricated on the first sample two-dimensional transition metal dichalcogenide layer. A second sample dielectric layer is fabricated on the second sample two-dimensional transition metal dichalcogenide layer. A second sample gate layer is fabricated on the second sample dielectric layer, thereby obtaining a sample device. The first sample dielectric layer and the second sample dielectric layer can be made of the same or different materials, but the first sample two-dimensional transition metal dichalcogenide layer and the second sample two-dimensional transition metal dichalcogenide layer can be made of different materials.

[0072] Step S503: Apply a voltage / electric field of a specified intensity through the first sample gate layer and the second sample gate layer.

[0073] Step S504: Irradiate the sample device with pump light and perform spatial scanning with delayed probe light to obtain a transient absorption image of the sample, wherein the pump light can excite the two-dimensional transition metal dichalcogenide layer of the first sample to generate excitons.

[0074] The pump light needs to be able to excite the two-dimensional transition metal dichalcogenide layer of the first sample to generate excitons. In one example, the pump light cannot excite the two-dimensional transition metal dichalcogenide layer of the second sample to generate excitons, thereby eliminating the influence of the two-dimensional transition metal dichalcogenide layer of the second sample and further improving the accuracy of detection.

[0075] Step S505: Calculate the diffusion index value of each sample based on the transient absorption image of each sample.

[0076] Step S506: Establish the correspondence between the degree of sample defect and the value of the sample diffusion index.

[0077] In one example, different degrees of sample defects can be set at different locations on the surface of the dielectric layer of the first sample, so that the correspondence between the degree of multiple sample defects and the sample diffusion index value can be established through a single measurement.

[0078] Step S507: Select other sample dielectric layers to continue establishing the correspondence between defect degree and diffusion index value until a preset number of pairs of correspondences are obtained. The sample dielectric layer and the other sample dielectric layers have the same material type and the same defect type of the interface subsurface atomic level defects.

[0079] In establishing the same quantitative correspondence, the selected samples have the same dielectric layer material type and the same defect type. The preset number can be customized according to the actual situation; the more preset numbers, the more accurate the obtained quantitative correspondence.

[0080] Step S508: Fit the correspondence of the preset number pairs to obtain the quantitative correspondence of the material type of the sample dielectric layer under a specified voltage / electric field.

[0081] In this embodiment of the invention, by combining the state transition threshold and broadening driven by the vertical electric field, as well as the shielding effect under exciton density / doping conditions, a multi-dimensional defect fingerprint can be formed, improving the ability to distinguish different defect sources (friction vacancies, interface residues, local strain, etc.). Introducing voltage / electric field conditions during the establishment of quantitative correspondences allows for the acquisition of quantitative correspondences under specified voltage / electric field intensities, thus making it applicable to online detection of dual-gate van der Waals heterostructure devices in operation.

[0082] The following is a specific example illustrating the method for establishing the quantitative correspondence of the present invention, including: Step C1: Prepare a first dielectric layer of hBN material on the first gate layer (graphene material).

[0083] Step C2 involves controlled tribology on the surface of the first dielectric layer using a contact AFM probe to introduce subsurface atomic-level disorder or vacancy defects with tunable density. Tribology parameters can be characterized by normal load, scanning speed, number of cycles, and scanning area size. This step can also be replaced by other controlled tribology / polishing processes (e.g., micro-area chemical mechanical polishing (CMP), nano-scraping, etc.) to introduce defects of different types or densities.

[0084] Step C3 involves calibrating the first dielectric layer after adding defects using electron microscopy (e.g., STEM). Taking vacancy defects as an example, vacancy sites are identified based on the decrease in atomic pillar intensity, and the number of vacancies Nv and area A within the region are statistically analyzed. The vacancy density nd = Nv / A is calculated as the degree of atomic-level defects in the subsurface layer of the interface. The correspondence between different normal loading forces and different vacancy densities is as follows: Figure 6 As shown, from Figure 6 As can be seen, when the normal force of the contact AFM probe is 100nN, 1000nN, 2000nN, and 3000nN, the friction force is between 0nN and 2nN, and the corresponding defect (vacancy) density is 1.52 × 10⁻⁶. 12 cm -2 4.57×10 12 cm -2 6.10×10 12 cm -2 9.14×10 12 cm -2 The functional relationship between the frictional force in the corresponding region and the normal load is as follows: Figure 7 As shown, the error bars at each point represent the standard deviation based on measurements of 512 friction cycles. Through analysis of... Figure 7 The friction coefficient extracted by linear fitting of the friction force-normal load curve can yield a functional relationship between the friction coefficient and the change in vacancy density, for example... Figure 8 As shown.

[0085] Step C4 continues to complete the fabrication of the dual-gate van der Waals heterostructure device, including: a first two-dimensional transition metal dichalcogenide layer (WS2 material), a second two-dimensional transition metal dichalcogenide layer (MoSe2 material), a second dielectric layer (hBN material), and a second gate layer (graphene material).

[0086] Step C5 involves performing spatiotemporally resolved measurements of hybrid excitons in the device using ultrafast pump-probe transient absorption microscopy: electrons are excited using pump light, and a transient absorption image is acquired by spatial scanning with delayed probe light; in one embodiment, see [link to embodiment]. Figure 9 The pump light energy is 1.67 eV, the probe light energy is 1.98 eV, and the vertical electric field is Ez=0. The optically injected exciton density is approximately 1×10⁻⁶. 12 cm -2 Under certain conditions, diffusion images (i.e., transient absorption images) with different delay times are obtained, such as... Figure 10 and Figure 11 As shown, ΔR is the relative change in reflectivity of the first dielectric layer interface (Delta Reflectance), which is the normalized value of the difference between the sample reflection signal measured by the probe light at different delay times after pump light excitation and the initial state. Figure 12 for Figure 10 Representative line profiles extracted along the x-direction from the mid-space mapping, and Gaussian fitting results for different pump-probe delay times. Figure 13 The transmission variance increment extracted based on the Gaussian width ( - It can be seen that the vacancy density increases from 0.78 × 10⁻⁶. 13 cm -2 Increased to 6.25×10 13 cm -2 At that time, the hybrid exciton diffusion distance decreased by nearly an order of magnitude.

[0087] Step C6: Perform Gaussian fitting on the spatial distribution of excitons in the transient absorption image at each delay time to obtain the standard deviation and variance. Define the diffusion variance increment = - In step C3, the vacancy density of each region has been obtained. The correspondence between the vacancy density at each location and the increase in diffusion variance has been established, as follows: Figure 6 As shown, the vacancy density is 1.52 × 10⁻⁶. 12 cm -2 4.57×10 12 cm -2 6.10×10 12 cm -2 9.14×10 12 cm -2 At that time, the corresponding diffusion variance increment - The corresponding depths are 0.23 μm, 0.18 μm, 0.14 μm, and 0.11 μm. In other possible examples, for isotropic two-dimensional conventional diffusion, the following can be used: = Extracting the diffusion coefficient It can also be used with a fixed delay time (e.g., 500ps). As a characteristic quantity that monotonically corresponds to the defect density, the final quantitative correspondence of hBN under zero electric field is as follows: Figure 14 As shown.

[0088] It is understood that the above embodiments are merely examples. This invention is applicable to various two-dimensional heterostructure material systems and various types of defects introduced by friction / polishing. It can serve as a feedback index for optimizing interface treatment processes (such as AFM cleaning, polishing / planarization parameters), providing a basis for defect tolerance assessment in large-scale manufacturing. It can be repeatedly measured under different exciton densities or charge doping conditions to evaluate the degree of attenuation of the defect effect by carrier shielding, characterize the "defect-Coulomb shielding" coupling mechanism, and improve the inversion robustness under complex operating conditions. Furthermore, the material system can be extended to other two-dimensional semiconductor heterostructures such as WSe2 / MoSe2, MoS2 / WSe2, and WS2 / WSe2; the defect types can be extended to sulfur / selenium vacancies, boron / nitrogen vacancies, substitutional impurities, and local disorder caused by interface contamination residues. All of these are within the scope of protection of this application.

[0089] The apparatus for nondestructive testing of subsurface atomic-level defects based on exciton diffusion provided by the present invention is described below. The apparatus for nondestructive testing of subsurface atomic-level defects based on exciton diffusion described below can be referred to in correspondence with the method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion described above.

[0090] The device for nondestructive testing of subsurface atomic-level defects based on exciton diffusion provided by the present invention includes: An image acquisition module is used to irradiate a device with pump light and perform spatial scanning with delayed probe light to obtain a transient absorption image. The device includes a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The two-dimensional transition metal dichalcogenide layer and the dielectric layer are arranged in contact. The pump light can excite the two-dimensional transition metal dichalcogenide layer to generate excitons. The index calculation module is used to calculate the diffusion index based on each of the transient absorption images to obtain the target diffusion index value; The result determination module is used to query the quantitative correspondence between the material type of the dielectric layer, determine the degree of atomic-level defects in the subsurface interface corresponding to the target diffusion index value, and obtain the detection result of the atomic-level defects in the subsurface interface of the dielectric layer. The quantitative correspondence is a pre-established correspondence between the diffusion index and the degree of atomic-level defects in the subsurface interface.

[0091] In one possible implementation, the index calculation module is specifically used to: perform Gaussian fitting on the spatial distribution of excitons in the transient absorption image shown under different delays to obtain the standard deviation and variance; obtain the initial variance of the pump light; and calculate the value of the diffusion variance increment based on the standard deviation and variance and the initial variance, wherein the diffusion index includes the diffusion variance increment.

[0092] In one possible implementation, the index calculation module is specifically used to: calculate the value of the diffusion variance increment according to the following formula: = - ;in, For the diffusion variance increment, For standard deviation and variance, This represents the initial variance.

[0093] In one possible implementation, the index calculation module is specifically used to: perform Gaussian fitting on the spatial distribution of excitons in the transient absorption image shown under different delays to obtain the standard deviation and variance; obtain the initial variance of the pump light; and calculate the value of the diffusion coefficient based on the standard deviation and variance and the initial variance, wherein the diffusion index includes the diffusion coefficient.

[0094] In one possible implementation, the index calculation module is specifically used to: calculate the value of the diffusion coefficient according to the following formula: = ;in, For standard deviation and variance, Let be the initial variance, t be the delay time, and D be the diffusion coefficient.

[0095] In one possible implementation, the device is a dual-gate van der Waals heterostructure device, comprising a first gate layer, a first dielectric layer, a first two-dimensional transition metal dichalcogenide layer, a second two-dimensional transition metal dichalcogenide layer, a second dielectric layer, and a second gate layer stacked sequentially; the first two-dimensional transition metal dichalcogenide layer is fabricated on the interface of the first dielectric layer, and the pump light can excite the first two-dimensional transition metal dichalcogenide layer to generate excitons; the device further includes an electric field application module for applying a voltage / electric field of a specified intensity through the first gate layer and the second gate layer; the quantitative correspondence is the quantitative correspondence of the material type of the dielectric layer under the specified intensity of voltage / electric field.

[0096] In one possible implementation, the apparatus further includes: a quantitative correspondence, used for: detecting subsurface atomic-level defects at the interface of the sample dielectric layer using a scanning transmission electron microscope to obtain the sample defect degree; preparing a sample two-dimensional transition metal dichalcogenide layer on the interface of the sample dielectric layer to obtain a sample device; irradiating the sample device with pump light and performing spatial scanning with delayed probe light to obtain a sample transient absorption image, wherein the pump light can excite the sample two-dimensional transition metal dichalcogenide layer to generate excitons; calculating a diffusion index value based on each sample transient absorption image to obtain a sample diffusion index value; establishing a correspondence between the sample defect degree and the sample diffusion index value; selecting other sample dielectric layers to continue establishing a correspondence between the defect degree and the diffusion index value until a preset number of correspondences are obtained, wherein the sample dielectric layer and the other sample dielectric layers have the same material type and the same defect type at the subsurface atomic level; fitting the preset number of correspondences to obtain a quantitative correspondence corresponding to the material type of the sample dielectric layer.

[0097] In one possible implementation, the sample device includes a first sample gate layer, a first sample dielectric layer, a first sample two-dimensional transition metal dichalcogenide layer, a second sample two-dimensional transition metal dichalcogenide layer, a second sample dielectric layer, and a second sample gate layer stacked sequentially; the first sample two-dimensional transition metal dichalcogenide layer is fabricated on the interface of the first sample dielectric layer, and the pump light can excite the first sample two-dimensional transition metal dichalcogenide layer to generate excitons; the quantitative correspondence is further used to: apply a voltage / electric field of a specified intensity through the first sample gate layer and the second sample gate layer; fit the correspondence of the preset number pairs to obtain a quantitative correspondence of the material type of the sample dielectric layer under the specified intensity of voltage / electric field.

[0098] In one possible implementation, the defect type of the interface subsurface atomic-level defect is one of vacancy, substitution, or disorder.

[0099] In one possible implementation, the material of the same dielectric layer is one of the following: hexagonal boron nitride, silicon dioxide, aluminum oxide, hafnium dioxide, and titanium dioxide.

[0100] In one possible implementation, the material of the same two-dimensional transition metal dichalcogenide layer is one of the following: tungsten disulfide, molybdenum diselenide, tungsten diselenide, or molybdenum disulfide.

[0101] Figure 15 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 15As shown, the electronic device may include a processor 810, a communications interface 820, a memory 830, and a communication bus 840, wherein the processor 810, the communications interface 820, and the memory 830 communicate with each other via the communication bus 840. The processor 810 can call logical instructions in the memory 830 to execute any of the exciton diffusion-based nondestructive testing methods for subsurface atomic-level defects described in this application.

[0102] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0103] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute any of the exciton diffusion-based nondestructive testing methods for subsurface atomic-level defects described in this application.

[0104] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform any of the exciton diffusion-based nondestructive testing methods for subsurface atomic-level defects described in this application.

[0105] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0106] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, characterized in that, include: The device is irradiated with pump light and spatially scanned with delayed probe light to obtain transient absorption images. The device includes a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The two-dimensional transition metal dichalcogenide layer and the dielectric layer are arranged in contact. The pump light can excite the two-dimensional transition metal dichalcogenide layer to generate excitons. Based on the transient absorption images described above, the diffusion index is calculated to obtain the target diffusion index value; The quantitative correspondence between the material type of the dielectric layer is queried to determine the degree of atomic-level defects in the subsurface layer of the interface corresponding to the target diffusion index value, thereby obtaining the detection result of the atomic-level defects in the subsurface layer of the dielectric layer. The quantitative correspondence is a pre-established correspondence between the diffusion index and the degree of atomic-level defects in the subsurface layer of the interface.

2. The method according to claim 1, characterized in that, The step of calculating the diffusion index to obtain the target diffusion index value based on each of the transient absorption images includes: Gaussian fitting was performed on the spatial distribution of excitons in the transient absorption images under different delays to obtain the standard deviation and variance. Obtain the initial variance of the pump light, and calculate the value of the diffusion variance increment based on the standard deviation and the initial variance, wherein the diffusion index includes the diffusion variance increment.

3. The method according to claim 1, characterized in that, The step of calculating the diffusion index to obtain the target diffusion index value based on each of the transient absorption images includes: Gaussian fitting was performed on the spatial distribution of excitons in the transient absorption images under different delays to obtain the standard deviation and variance. Obtain the initial variance of the pump light, and calculate the value of the diffusion coefficient based on the standard deviation and the initial variance, wherein the diffusion index includes the diffusion coefficient.

4. The method according to claim 3, characterized in that, The calculation of the diffusion coefficient value based on the standard deviation, variance, and initial variance includes: The diffusion coefficient is calculated using the following formula: = ； in, For standard deviation and variance, Let be the initial variance, t be the delay time, and D be the diffusion coefficient.

5. The method according to claim 1, characterized in that, The device is a dual-gate van der Waals heterostructure device, which includes a first gate layer, a first dielectric layer, a first two-dimensional transition metal dichalcogenide layer, a second two-dimensional transition metal dichalcogenide layer, a second dielectric layer, and a second gate layer stacked sequentially. The first two-dimensional transition metal dichalcogenide layer is fabricated on the interface of the first dielectric layer, and the pump light can excite the first two-dimensional transition metal dichalcogenide layer to generate excitons. The method further includes: applying a voltage / electric field of a specified intensity through the first gate layer and the second gate layer; The quantitative correspondence is the quantitative correspondence between the material type of the dielectric layer and the voltage / electric field of a specified intensity.

6. The method according to claim 1, characterized in that, The steps for pre-establishing the quantitative correspondence include: The degree of defect in the sample was obtained by detecting subsurface atomic-level defects in the dielectric layer of the sample using scanning transmission electron microscopy. A two-dimensional transition metal dichalcogenide layer is prepared on the interface of the sample dielectric layer to obtain the sample device. The sample device is irradiated with pump light, and a transient absorption image of the sample is obtained by spatial scanning with delayed probe light. The pump light can excite the two-dimensional transition metal dichalcogenide layer of the sample to generate excitons. Based on the transient absorption images of each sample, the diffusion index is calculated to obtain the sample diffusion index value; Establish the correspondence between the degree of sample defect and the value of the sample diffusion index; Select other sample dielectric layers to continue establishing the correspondence between defect degree and diffusion index value until a preset number of pairs of correspondence are obtained. The sample dielectric layer and the other sample dielectric layers have the same material type and the same defect type of the interface sub-surface atomic level defect. By fitting the correspondence of the preset number pairs, a quantitative correspondence is obtained for the material type of the sample dielectric layer.

7. The method according to claim 6, characterized in that, The sample device comprises a first sample gate layer, a first sample dielectric layer, a first sample two-dimensional transition metal dichalcogenide layer, a second sample two-dimensional transition metal dichalcogenide layer, a second sample dielectric layer, and a second sample gate layer stacked sequentially; the first sample two-dimensional transition metal dichalcogenide layer is prepared on the interface of the first sample dielectric layer, and the pump light can excite the first sample two-dimensional transition metal dichalcogenide layer to generate excitons; The method further includes: applying a voltage / electric field of a specified intensity through the first sample gate layer and the second sample gate layer; The step of fitting the correspondence of the preset number pairs to obtain the quantitative correspondence of the material type of the sample dielectric layer includes: fitting the correspondence of the preset number pairs to obtain the quantitative correspondence of the material type of the sample dielectric layer under a specified voltage / electric field.

8. The method according to claim 1 or 6, characterized in that, The defect type of the subsurface atomic-level defect at the interface is one of vacancy, substitution, or disorder.

9. The method according to claim 1, characterized in that, The dielectric layer is made of one of the following materials: hexagonal boron nitride, silicon dioxide, aluminum oxide, hafnium dioxide, and titanium dioxide; the two-dimensional transition metal dichalcogenide layer is made of one of the following materials: tungsten disulfide, molybdenum diselenide, tungsten diselenide, and molybdenum disulfide.

10. A device for nondestructive testing of subsurface atomic-level defects based on exciton diffusion, characterized in that, include: An image acquisition module is used to irradiate a device with pump light and perform spatial scanning with delayed probe light to obtain a transient absorption image. The device includes a two-dimensional transition metal dichalcogenide layer and a dielectric layer. The two-dimensional transition metal dichalcogenide layer and the dielectric layer are arranged in contact. The pump light can excite the two-dimensional transition metal dichalcogenide layer to generate excitons. The index calculation module is used to calculate the diffusion index based on each of the transient absorption images to obtain the target diffusion index value; The result determination module is used to query the quantitative correspondence between the material type of the dielectric layer, determine the degree of atomic-level defects in the subsurface interface corresponding to the target diffusion index value, and obtain the detection result of the atomic-level defects in the subsurface interface of the dielectric layer. The quantitative correspondence is a pre-established correspondence between the diffusion index and the degree of atomic-level defects in the subsurface interface.

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