Nondestructive testing method for surface carrier mobility of high-resistance semiconductor material for radiation detection

Abstract

The invention provides a nondestructive testing method for the surface carrier mobility of a high-resistance semiconductor material for radiation detection. The nondestructive testing method solves the problems that according to an existing testing method for the surface carrier mobility of the high-resistance semiconductor material for radiation detection, testing conditions are tedious, and the surface of the material is damaged in the testing process. According to the invention, based on a low-energy electrode bonding process, nondestructive contact and separation between the electrode and the surface of the to-be-detected sample are realized by adopting a flexible patch, and rapid and accurate detection of the carrier mobility on the surface of the to-be-detected sample is realized by preparing a field effect transistor structure on the surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor nondestructive testing, and in particular relates to a nondestructive testing method for surface carrier mobility of a high-resistance semiconductor material for radiation detection. Background Art

[0002] Radiation, as an electromagnetic wave with high energy and penetrating power, can carry information such as the thickness and material of the objects it passes through. Radiation detection technology holds an irreplaceable position as a core technology in fields such as security inspection, medical imaging, and industrial non-destructive testing. However, radiation is an electromagnetic wave signal that cannot be directly collected and must be converted into an electrical signal using a radiation detector. The performance of the detection material, a core component of radiation detectors, directly determines the effectiveness of detection.

[0003] Among the many detection materials, many high-resistance semiconductors (resistivity of 1×10 8 -1×10 12 Ω·cm) can directly detect radiation. Leveraging its high atomic number and wide bandgap, it enables high-precision radiation detection at room temperature. Radiation detection devices fabricated with high-resistance semiconductors as their core materials are widely used. However, the fabrication process of high-resistance semiconductor single crystals often faces complex heat and mass transfer conditions, making them prone to the formation of tiny, difficult-to-observe defects such as compositional segregation, interstitial atoms, and atomic vacancies, which can degrade material properties. Furthermore, subsequent processing steps such as cutting, polishing, and passivation can also affect material properties.

[0004] Carrier mobility is one of the most important indicators affecting the radiation detection capability of high-resistance semiconductors and has always been the key to performance testing. However, for high-resistance, low-mobility materials (such as CdZnTe and CdTe), traditional Hall effect test results cannot reflect the carrier mobility of radiation detection devices during operation, and the test results are completely inconsistent with the actual situation. Therefore, realizing carrier mobility testing of high-resistance semiconductor radiation detection materials represented by CdZnTe is of great significance to the application and promotion of high-resistance semiconductors for radiation detection and the future development of the radiation detection field.

[0005] Reference 1 “R. Guo, W. Jie, G. Zha, Y. Xu, T. Feng, T. Wang, and Z. Du, Effect of de-trapping on carrier transport process in semi-insulating CdZnTe, Chinese Phys. B, 24(6), 067203, 2015” reported that a self-built LBIC (Laser Beam Induced Transient Current, LBIC) detection system can be used to test key parameters of CdZnTe materials that affect the radiation detection performance of the material, such as carrier mobility and space charge concentration. However, the test process requires that the laser pulse width be much smaller than the transit time of the material. For CdZnTe materials, the required picosecond laser is expensive. At the same time, an appropriate amount of photogenerated carrier injection is also required. Too much or too little injection will seriously affect the accuracy of the test results. Moreover, fluctuations in the performance of the material itself will bring about cumbersome test condition changes and matching requirements, resulting in low detection efficiency.

[0006] Reference 2, "Erickson J., Yao H., James R., et al. Time of flight experimental studies of CdZnTe radiation detectors [J]. Journal of Electronic Materials, 2000, 29 (6): 699-703," reported that the use of a TCT (Transient Current Technique) detection system can measure the carrier mobility of CdZnTe and CdTe materials. However, the test results are severely affected by the electric field distribution inside the semiconductor material, and the electric field distortion will cause the test results to not match the actual values. Affected by the polarization effect, the electric field inside the CdZnTe material will be distorted over time, and the long-term stability of the electric field cannot be guaranteed. Therefore, the data results obtained from the TCT test can only reflect the instantaneous carrier mobility, and the errors in the results of multiple tests are large.

[0007] The above reports all used electrical test analysis to measure the carrier mobility of high-resistance semiconductors and obtained experimental results with reference value. However, the above test methods still face problems such as cumbersome test methods and unstable test results. At the same time, the above electrical test analysis all require the use of evaporation, magnetron sputtering and other methods to prepare electrodes on the surface of the material to realize signal extraction, but the preparation of the electrode itself will destroy the surface state of the material, causing changes in the performance of the material and causing obvious damage. In view of the problems existing in the current carrier mobility test of high-resistance semiconductors for radiation detection, it is urgent to propose a method that can achieve fast, stable and non-destructive carrier mobility testing of high-resistance semiconductor materials such as cadmium zinc telluride for radiation detection. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems of the current method for testing the carrier mobility of high-resistance semiconductor materials for radiation detection, such as complicated testing conditions and damage to the material surface during the testing process, and to provide a non-destructive testing method for the surface carrier mobility of high-resistance semiconductor materials for radiation detection.

[0009] To achieve the above objectives, the technical solutions provided by the present invention are:

[0010] A nondestructive testing device for surface carrier mobility of high-resistance semiconductor materials used for radiation detection. Its unique features include: a flexible patch, a volt-ampere test system, a high-voltage source, and a host computer. In actual use, some auxiliary tooling may also be used, such as a patch base and a sample table.

[0011] The flexible patch is used to be attached to the surface of a sample to be tested during testing, and includes a flexible substrate, a gate, and electrodes. The gate and electrodes are respectively arranged on the upper and lower surfaces of the flexible substrate. The electrodes include a source electrode and a drain electrode arranged at intervals. The gate does not directly contact the sample to be tested and only serves as a medium for providing an external electric field. The flexible patch must meet the following requirements:

[0012] ① The conductivity of the material used for the source electrode and the drain electrode is greater than 10 6 S / M, work function ≥ 5eV, avoid the influence of Schottky barrier of gold-semiconductor contact on test results, ensure near-ohmic contact on semiconductor surface; 10nm≤thickness≤1μm;

[0013] The conductivity of the gate material is greater than 10 6 S / M, 10 nm ≤ thickness ≤ 1 μm;

[0014] The size, shape, and position distribution of the source and drain electrodes must ensure that a uniform electric field can be established on the surface of the sample material to be tested, and that this can be achieved under test conditions where the voltage does not exceed 1000V, with a maximum uniform electric field strength of ≥500V / cm; the position and size of the gate should be able to completely cover the uniform electric field area between the drain and source electrodes;

[0015] ② The lower surface of the flexible substrate (i.e., the surface where the electrode is located, the area that contacts the surface of the sample to be tested) is adhesive, and when it is attached to the sample to be tested and then separated, the adhesion work between the electrode and the sample to be tested is less than the adhesion work between the flexible substrate and the electrode; there are no special requirements for the upper surface of the flexible substrate, as long as the gate and the flexible substrate are firmly bonded;

[0016] ③ The average relative dielectric constant of the material used for the flexible substrate is 1-5, and the thickness is 0.1mm≤≤1mm (the requirements for dielectric constant and thickness are to ensure that subsequent electrical tests can proceed smoothly and that the required test conditions can be easily provided without providing ultra-high voltages exceeding 2kV to ensure the feasibility of the detection experiment). At the same time, the surface undulation error of the flexible substrate is less than 1% of the thickness, and the size of the flexible substrate can achieve electrode extraction while ensuring full coverage of the test sample; here, the undulation error is similar to the description of material surface flatness, and is used to characterize the flatness of the area where the flexible patch and the test material are bonded;

[0017] Assume that the entire flexible substrate is composed of 1, 2, 3, ..., n types of materials stacked in a uniform thickness, and their thicknesses are d1, d2, d3, ..., d n , whose relative dielectric constants are ε1, ε2, ε3, ..., ε n ; The average relative dielectric constant of the integrated flexible substrate is It can be calculated by the following formula:

[0018] Total thickness of flexible substrate:

[0019] Average relative dielectric constant:

[0020] If the entire flexible substrate does not meet the requirements of laminated integration with uniform thickness, the relative dielectric constant of the entire flexible substrate should be ensured to be uniform using a standard dielectric constant test method to obtain the average relative dielectric constant of the flexible substrate;

[0021] ④ There are no independent requirements for the flexibility of the flexible substrate, gate, and electrode. However, the thickness of the fully integrated flexible patch is required to be 0.1-1mm. When the flexible patch is bent at an angle of θ = 180°, if elastic deformation occurs, its bending radius is less than 50% of the length of the flexible patch. The elastic modulus of the flexible patch is 1-5GPM.

[0022] ⑤ The flexible patch has the ability to be stored in air at room temperature and pressure for at least 72 hours without changing its physical and chemical properties;

[0023] The flexible patch meets the above requirements to ensure that the flexible patch can fit tightly with the surface of the sample material to be tested and perform the test normally;

[0024] The voltammetric testing system is connected to the electrodes;

[0025] The high voltage source is connected to the gate;

[0026] The host computer is connected to the volt-ampere test system and the high voltage source, and is used to realize continuous voltage change of the high voltage source and the volt-ampere test system and collect data.

[0027] Furthermore, after the lower surface of the flexible substrate contacts the sample to be tested, the equivalent trapped charge concentration per unit area of the lower surface is 10 -10 -10 -7 C / cm -2 There is no requirement on the upper surface of the flexible substrate.

[0028] Furthermore, when the separation tip speed is 0.1-0.001 mm / s, the adhesion work between the flexible substrate and the electrode is greater than 0.2 J / m 2 .

[0029] Furthermore, the source electrode and the drain electrode are made of the same material, which is beneficial to subsequent test result analysis.

[0030] Furthermore, the flexible substrate, electrodes and gate can be integrated with a variety of materials; for example, the flexible substrate can adopt a composite substrate of PDMS-PC (polydimethylsiloxane-polycarbonate copolymer), in which the PDMS used as the adhesive layer can also be replaced by polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyimide (PI), etc., which can meet the requirements.

[0031] At the same time, the present invention also provides a nondestructive testing method for the surface carrier mobility of a high-resistance semiconductor material for radiation detection using the above-mentioned nondestructive testing device, which is special in that it includes the following steps:

[0032] Step 1: Process the sample to be tested

[0033] Before processing, the sample to be tested should be a complete single crystal without macro defects (such as grain boundaries, holes, cracks, inclusions, etc.), and the resistivity of the sample material to be tested should be: 1×10 8 -1×10 12 Ω·cm; after treatment, the sample to be tested meets the following requirements:

[0034] ① The length and width of the sample to be tested are both ≥ 1mm; this requirement is intended to achieve the minimum contact area requirement for carrier mobility detection. Since the present invention uses a flexible patch for detection, a slightly larger area is not a problem, so only the minimum size is limited;

[0035] ② The waviness of the surface of the sample to be tested is greater than 5mm (the greater the waviness, the better the flatness, and the more favorable it is for the flexible patch to fit), and the maximum height of the surface roughness profile is less than 100nm (the smaller the roughness value, the better the flatness, but there is a certain processing limit due to the influence of the processing technology. However, for the present invention, this requirement can be achieved using a common grinding and polishing process). Both of these requirements put forward requirements for the surface flatness of the sample to be tested, aiming to ensure that the flexible patch and the sample to be tested fit smoothly without bubbles or wrinkles; in order to prevent the sample to be tested from scratching the electrode and affecting the test, the edge chamfer is 35° < 55°;

[0036] The sample to be tested meeting the above requirements is conducive to the complete fit of the flexible patch used for testing and the surface of the sample material to be tested, thereby avoiding large detection errors or no test results;

[0037] The surface of the sample material to be tested may be polished or passivated with chemical reagents (gases), but the difference in test results caused by the treatment should not be considered as experimental error of the detection equipment. Those skilled in the art know how to identify the source of error. The repeatability comparison of the test results of the present invention should be carried out on the same material samples to be tested using the same surface treatment process;

[0038] Step 2: Attach the flexible patch of the nondestructive testing device to the surface of the sample to be tested

[0039] Lay the side of the flexible patch with electrodes on the surface of the sample to be tested (avoid wrinkles and bubbles when laminating to ensure that a uniform electric field can be formed between the source electrode and the drain electrode on the surface of the sample material to be tested during subsequent testing). Connect the source electrode and the drain electrode to the voltage source of the voltammetric test system through a conductive material, and connect the gate to an independent high-voltage source. Ensure that the connection resistance between the three electrodes of the flexible patch and their respective voltage sources is ≤10Ω. In practice, the smaller the connection resistance, the better;

[0040] Step 3: Use the flexible patch to test the electrical properties of the sample to be tested

[0041] Test conditions: The maximum voltage between the source and drain electrodes can ensure that the source-drain current is ≥100nA, and the independent high-voltage source used for the gate can achieve a voltage supply of 0-2000V;

[0042] Conduct electrical performance tests according to the above test conditions to obtain the transfer characteristic curve of the sample to be tested;

[0043] The carrier mobility of the sample to be tested is obtained by fitting the transfer characteristic curve.

[0044] Furthermore, the thickness of the sample to be tested is ≤5 mm.

[0045] Furthermore, the sample material to be tested is cadmium zinc telluride.

[0046] The concept and principle of the present invention are:

[0047] High-resistance semiconductors, such as cadmium zinc telluride (CdZnTe), are ternary compounds. During material preparation, they inevitably develop various defects that affect surface carrier mobility, necessitating crystal performance testing before further application. However, current methods for testing CdZnTe surface carrier mobility suffer from cumbersome testing conditions and surface damage during testing. Therefore, developing a method for rapid and non-destructive testing of high-resistance semiconductor surfaces is crucial for their application and development in radiation detection.

[0048] After careful analysis, the research team behind this invention concluded that surface damage in existing testing methods stems from high-energy metal bombardment during electrode preparation, which severely damages the original surface state of the sample material being tested, rendering the test destructive. Therefore, constructing a non-destructive electrode can avoid surface damage caused by testing. This invention, based on a low-energy electrode bonding process, achieves non-destructive contact and separation between the metal electrode and the surface of the sample material being tested, avoiding surface damage to the sample material. The reusable transfer electrode also significantly simplifies the preparation process required for device testing.

[0049] The detection of carrier mobility requires exciting non-equilibrium carriers and understanding the law of change in the number of excited non-equilibrium carriers. Although the existing test methods are based on the Hall magnetic field effect and the semiconductor photoelectric effect, they can achieve the quantitative injection of non-equilibrium carriers, but they are affected by the internal self-built electric field, and the carrier transport process is disturbed, which affects the accuracy of the detection. The non-equilibrium carrier excitation method based on the electric field effect can simultaneously achieve the quantitative injection and electric field control of non-equilibrium carriers, but the required excitation conditions are closely related to the characteristics of the sample material itself. For common low-resistance semiconductors, such as Si, Ge, etc., if a flexible patch is designed based on the idea of the present invention (i.e., based on the field effect transistor principle) to detect its surface carrier mobility, the required flexible patch thickness does not exceed several hundred nanometers. This design does not have the conditions for physically achieving lossless contact and separation, and has no practical feasibility. For insulating materials, such as metal oxides like Al2O3 and SiO2, designing a flexible patch based on the principles of the present invention to test their surface carrier mobility requires not only a thickness exceeding tens of millimeters but also a gate voltage of several thousand volts. The ultra-high voltage electric field conditions required for this design are too demanding for common testing methods and are also impractical. However, for the high-resistance semiconductor materials discussed in this invention, the required flexible patch thickness is on the millimeter level, meeting the physical requirements for lossless contact and separation. The required gate voltage is several hundred volts, well within an acceptable range, allowing testing in an ordinary laboratory.

[0050] To this end, the present invention proposes a non-destructive testing scheme for the surface mobility of high-resistance semiconductors for radiation detection. A flexible patch is used to achieve non-destructive contact between the electrode and the surface of cadmium zinc telluride. Further, a field-effect transistor structure is prepared on the surface to achieve rapid and accurate detection of the surface carrier mobility of cadmium zinc telluride.

[0051] The advantages of the present invention are:

[0052] 1. The present invention enables rapid detection of carrier mobility in samples. While the sample processing of the present detection method is consistent with detection techniques such as LBIC and TCT, subsequent testing does not require the preparation of electrodes on the surface of the sample to be tested. This allows for direct testing of samples after raw material processing, reducing testing time and significantly improving sample detection efficiency.

[0053] 2. The present invention enables non-destructive testing of carrier mobility on the sample surface. For any detection technology that requires electrodes to be prepared on the sample surface for testing, after the surface electrodes are prepared using methods such as thermal evaporation and magnetron detection, the sample surface will inevitably produce a damaged layer due to the impact of high-energy atoms. This damage occurs during the detection process, but will affect the subsequent use of the sample. In the present invention, the contact between the flexible patch and the sample surface is carried out in a low-energy state, avoiding the appearance of a damaged layer and not affecting the subsequent use process.

[0054] 3. This invention enables repeated testing and continuous testing of multiple samples. The flexible detection system has a stability of over 72 hours under common conditions. After testing a sample once, the flexible patch can be non-destructively separated from the sample surface to continue testing the next sample, enabling continuous testing of multiple samples.

[0055] 4. This invention can significantly reduce testing costs. Compared to detection technologies such as LBIC and TCT, which use lasers to generate non-equilibrium carriers, the present invention's nondestructive testing device for surface carrier mobility in high-resistance semiconductor materials for radiation detection has a simple structure and can achieve carrier excitation using voltage alone. This non-customized high-voltage source offers significant cost advantages over customized picosecond lasers, which have specific requirements for laser wavelength and laser energy.

[0056] 5. The present invention can improve detection coverage and sample utilization. For any detection technology that requires electrodes to be prepared on the sample surface for detection, if the sample needs to be continued to be used after the detection is completed, if there is a need to change the electrodes, it will need to be reprocessed, which is time-consuming and labor-intensive, and the physical parameters of the sample will inevitably change. Detection using the present invention will not have any impact on the sample, and will not result in the discarding of random inspection samples. It can improve the utilization rate of processed samples while increasing the detection coverage, ensuring the stability of production samples.

[0057] 6. Patch-type contacts are commonly used in the transfer process of various two-dimensional materials and are used to achieve lossless contact between semiconductors and metal electrodes. The present invention is the first to realize the construction of a field-effect transistor of a high-resistance semiconductor based on patch-type contacts and achieve surface carrier mobility. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the principle of the flexible patch in the nondestructive testing device of the present invention;

[0059] The reference numerals are as follows:

[0060] 1-sample to be tested, 2-flexible substrate, 3-gate, 4-electrode;

[0061] Figure 2 This is a physical picture of the PDMS-PC composite substrate, gold electrode, and graphite gate flexible patch prepared in Example 1 of the present invention;

[0062] Figure 3 The transfer characteristic curve of the flexible patch prepared in Example 1 of the present invention tested on a cadmium zinc telluride sample at a gate voltage of -100-500V;

[0063] Figure 4 This is a transfer characteristic curve of the flexible patch prepared in Example 2 of the present invention tested on a cadmium zinc telluride sample at a gate voltage of -100-500V. DETAILED DESCRIPTION

[0064] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments:

[0065] The main innovation of the present invention is to construct a field-effect transistor of a high-resistance semiconductor based on patch-type contact and achieve surface carrier mobility. To this end, the present invention designs a non-destructive testing device for high-resistance semiconductors, including a flexible patch, a volt-ampere testing system, a high-voltage source and a host computer.

[0066] The flexible patch is used to adhere to the surface of the sample to be tested during testing. It includes a flexible substrate, a gate, and electrodes. The gate and electrodes are respectively arranged on the upper and lower surfaces of the flexible substrate. The electrodes include a source electrode and a drain electrode arranged at intervals. The preparation of the flexible patch must meet the following requirements:

[0067] ① The conductivity of the material used for the source electrode and the drain electrode is greater than 10 6 S / M, work function ≥ 5 eV, 10 nm ≤ thickness ≤ 1 μm;

[0068] The conductivity of the gate material is greater than 10 6 S / M, 10 nm ≤ thickness ≤ 1 μm;

[0069] The size, shape, and position distribution of the source and drain electrodes must ensure that a uniform electric field can be established on the surface of the sample material to be tested, and that this can be achieved under test conditions where the voltage does not exceed 1000V, with a maximum uniform electric field strength of ≥500V / cm; the position and size of the gate should be able to completely cover the uniform electric field area between the drain and source electrodes;

[0070] ② The lower surface of the flexible substrate is sticky, and when it is attached to the sample and then separated, the adhesion work between the electrode and the sample is smaller than the adhesion work between the flexible substrate and the electrode;

[0071] ③ The average relative dielectric constant of the material used for the flexible substrate is 1-5, the thickness is 0.1mm≤≤1mm, and the surface fluctuation error of the flexible substrate is less than 1% of the thickness. The size of the flexible substrate can ensure full coverage of the sample to be tested while enabling the electrode to be drawn out;

[0072] ④ The overall thickness of the flexible patch is 0.1-1mm. When the flexible patch is bent at an angle θ=180°, if elastic deformation occurs, the bending radius is less than 50% of the length of the flexible patch; the elastic modulus of the flexible patch is 1-5GPM;

[0073] ⑤ The flexible patch has the ability to be stored in air at room temperature and pressure for at least 72 hours without changing its physical and chemical properties;

[0074] The voltammetric test system is connected to the electrodes, and the maximum voltage between the source electrode and the drain electrode can ensure that the source-drain current is ≥100nA;

[0075] The high voltage source is connected to the gate, and the high voltage source used by the gate can achieve a voltage supply of 0-2000V;

[0076] The host computer is connected to the volt-ampere test system and the high voltage source to realize continuous voltage change of the high voltage source and the volt-ampere test system and collect data.

[0077] Example 1:

[0078] A nondestructive testing method for surface carrier mobility of a high-resistance semiconductor material for radiation detection comprises the following steps:

[0079] Step 1: Prepare the sample and flexible patch

[0080] Select a complete CdZnTe single crystal ingot and cut it into 5×5×2mm 3 The cadmium zinc telluride wafer is then mechanically polished, chemically polished, and chamfered to meet the requirements of the sample to be tested.

[0081] In this embodiment, a composite substrate of PDMS-PC (polydimethylsiloxane-polycarbonate copolymer) is selected as the flexible substrate of the flexible patch. A PDMS with a certain thickness and adhesiveness is prepared on the surface of PC. The thickness of the two is 0.8 mm, the average relative dielectric constant is 2.4, and the size is 7×10 mm. 2 , elasticity, viscosity and other related parameters meet the requirements. Subsequently, PDMS is used to tear off the pre-patterned gold electrode from the silicon wafer surface to realize the preparation of the source electrode and drain electrode. The spacing between the source electrode and the drain electrode is 2.5mm. Finally, carbon glue is applied to the PC surface and dried at room temperature for 30 minutes to realize the preparation of the gate. The prepared flexible patch is as follows Figure 2 shown.

[0082] Step 2: Attach the flexible patch to the surface of the sample to be tested

[0083] The electrode-equipped side of the flexible patch was placed on the surface of the CdZnTe material to be tested, achieving close contact between the two. The source and drain electrodes were extracted from the material surface using conductive rubber and conductive carbon adhesive. This was then connected to a Keithley 6517B volt-ampere characteristics test system to measure the IV characteristics between the source and drain electrodes after the flexible patch was bonded to the surface of the sample under test. The gate was connected to a Changsheng CS5051A high-voltage source to provide the required high voltage.

[0084] Step 3: Use the flexible patch to test the electrical properties of the sample to be tested

[0085] After confirming conduction, apply a voltage of 20-200V with a 10V interval between the source and drain electrodes, and test the change of source-drain current when the gate voltage changes from -100 to 500V at each source-drain voltage to obtain the transfer characteristic curve of the sample under different voltages, such as Figure 3 As shown, the electron carrier mobility of the sample to be tested is fitted to be 1029cm 2 / Vs.

[0086] This embodiment carried out multi-point testing, and the error of the test results did not exceed 5%, which can prove the stability of the nondestructive testing device and method of the present invention.

[0087] Example 2:

[0088] A nondestructive testing method for surface carrier mobility of a high-resistance semiconductor material for radiation detection comprises the following steps:

[0089] Step 1: Prepare the sample to be tested

[0090] Select a complete CdZnTe single crystal ingot and cut it into 5×5×1mm 3 The cadmium zinc telluride wafer is subsequently mechanically polished, chemically polished, and chamfered to meet the test sample requirements.

[0091] In this embodiment, a PDMS-PET composite substrate is selected as the flexible patch substrate. A PDMS with a certain thickness and adhesiveness is prepared on the PET surface. The thickness of the two is 0.4 mm, the average relative dielectric constant is 3.8, and the size is 6×10 mm. 2 , elasticity, viscosity, and other related parameters meet the requirements. PDMS is then used to peel the pre-patterned gold electrodes from the silicon wafer surface to fabricate the source and drain electrodes, with a spacing of 1 mm between them. Finally, silver paste is applied to the PC surface and dried at 120°C for 30 minutes, allowing the paste to completely solidify and complete the gate fabrication.

[0092] Step 2: Lay the flexible patch on the surface of the sample to be tested

[0093] The electrode-equipped side of the flexible patch was placed on the surface of the CdZnTe material to be tested, achieving close contact between the two. The source and drain electrodes were extracted from the material surface using conductive rubber and conductive carbon adhesive. These electrodes were then connected to a Keithley 6517B volt-ampere characteristics test system for subsequent IV characteristic curve testing of the device. The gate was connected to a Changsheng CS5051A high-voltage source to provide the required high voltage.

[0094] Step 3: Use the flexible patch to test the electrical properties of the sample to be tested

[0095] After confirming the conduction, a voltage of 20-200V with a 10V interval is applied between the source electrode and the drain electrode, and the change of the source-drain current when the gate voltage changes from -100 to 500V is tested at each source-drain voltage to obtain the transfer characteristic curve of the sample at different voltages, as shown in the figure below. Figure 4 As shown, the electron carrier mobility of the sample is fitted to be 1096 cm 2 / Vs.

[0096] Likewise, this embodiment conducted multi-point testing, and the error of the test results did not exceed 5%, further demonstrating the stability of the nondestructive testing device and method of the present invention.

[0097] In summary, the present invention not only has a simple testing method, high feasibility of testing conditions, stable test results, and can avoid damaging the surface of the sample material during the test process, but also can significantly reduce the testing cost, realize continuous testing of multiple samples, and improve testing efficiency.

[0098] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present invention, and these modifications or replacements should all be included in the scope of protection of the present invention.

Claims

1. A nondestructive testing device for surface carrier mobility of high-resistance semiconductor materials for radiation detection, characterized by: Including flexible patch, volt-ampere test system, high voltage source and host computer; The flexible patch is used to be attached to the surface of the sample to be tested during detection, and includes a flexible substrate, a gate, and electrodes; wherein the gate and the electrodes are respectively arranged on the upper surface and the lower surface of the flexible substrate; the electrodes include a source electrode and a drain electrode arranged at intervals; the flexible patch must meet the following requirements: ① The conductivity of the material used for the source electrode and the drain electrode is greater than 10 6 S / M, work function ≥ 5 eV, 10 nm ≤ thickness ≤ 1 μm; The conductivity of the gate material is greater than 10 6 S / M, 10 nm ≤ thickness ≤ 1 μm; The size, shape, and position distribution of the source and drain electrodes must ensure that a uniform electric field can be established on the surface of the sample material to be tested, and that this can be achieved under test conditions where the voltage does not exceed 1000V, with a maximum uniform electric field strength of ≥500V / cm; the position and size of the gate should be able to completely cover the uniform electric field area between the drain and source electrodes; ② The lower surface of the flexible substrate is sticky, and when it is attached to the sample and then separated, the adhesion work between the electrode and the sample is smaller than the adhesion work between the flexible substrate and the electrode; ③ The average relative dielectric constant of the material used for the flexible substrate is 1-5, and the surface fluctuation error of the flexible substrate is less than 1% of the thickness. The size of the flexible substrate can ensure full coverage of the sample to be tested while enabling the electrode to be drawn out; ④ The overall thickness of the flexible patch is 0.1-1mm. When the flexible patch is bent at an angle θ=180°, if elastic deformation occurs, the bending radius is less than 50% of the length of the flexible patch; the elastic modulus of the flexible patch is 1-5GPM; ⑤ The flexible patch has the ability to be stored in air at room temperature and pressure for at least 72 hours without changing its physical and chemical properties; The voltammetric testing system is connected to the electrodes; The high voltage source is connected to the grid; The host computer is connected to the volt-ampere test system and the high voltage source, and is used to realize continuous voltage change of the high voltage source and the volt-ampere test system and collect data.

2. The nondestructive testing device for surface carrier mobility of high-resistance semiconductor materials for radiation detection according to claim 1, characterized in that: After the lower surface of the flexible substrate contacts the sample to be tested, the equivalent trap charge concentration per unit area of the lower surface is 10 -10 -10 -7 C / cm -2 .

3. The nondestructive testing device for surface carrier mobility of high-resistance semiconductor materials for radiation detection according to claim 1 or 2, characterized in that: When the separation tip speed is 0.1-0.001 mm / s, the adhesion work between the flexible substrate and the electrode is greater than 0.2 J / m 2 .

4. The nondestructive testing device according to claim 3, characterized in that: The source electrode and the drain electrode are made of the same material.

5. The nondestructive testing method according to claim 4, characterized in that: The flexible substrate, electrodes and gate can be integrated from a variety of materials.

6. A method for nondestructive testing of surface carrier mobility of a high-resistance semiconductor material for radiation detection using the nondestructive testing device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Process the sample to be tested to meet the following requirements: ①The length and width of the sample to be tested are both ≥1mm; ② The waviness of the sample surface to be tested is greater than 5mm, the maximum height of the surface roughness profile is less than 100nm, and the edge chamfer is less than 35° and less than 55°; Step 2: Attach the flexible patch of the nondestructive testing device to the surface of the sample to be tested Place the side of the flexible patch with electrodes on the surface of the sample to be tested, lead the source electrode and drain electrode through the conductive material and connect them to the voltage source of the voltammetric test system, connect the gate to the high voltage source, and ensure that the connection resistance between the three electrodes of the flexible patch and their respective voltage sources is ≤10Ω; Step 3: Test the electrical properties of the sample to be tested Test conditions: The maximum voltage between the source and drain electrodes can ensure that the source-drain current is ≥100nA, and the high-voltage source used for the gate can achieve a voltage supply of 0-2000V; Conduct electrical performance tests according to the above test conditions to obtain the transfer characteristic curve of the sample to be tested; The carrier mobility of the sample to be tested is obtained by fitting the transfer characteristic curve.

7. The nondestructive testing method according to claim 6, characterized in that: The thickness of the sample to be tested is ≤5mm.

8. The nondestructive testing method according to claim 6, characterized in that: The sample material to be tested is cadmium zinc telluride.

Images