Method for repairing cadmium zinc telluride radiation detector with low energy resolution

Abstract

The invention provides a method for repairing a low-energy-resolution tellurium-zinc-cadmium radiation detector, and solves the problem that the detection performance of the detector is deteriorated or even completely damaged to influence the use due to the fact that the existing tellurium-zinc-cadmium radiation detector is damaged by the external environment in the service process. The core of the method is that the annealing furnace with the uniform temperature field is adopted, the tellurium-zinc-cadmium crystal is slowly heated to the set temperature in the inert gas atmosphere and then subjected to heat preservation, the crystal is cooled to the room temperature along with the furnace after heat preservation is finished, the performance of the tellurium-zinc-cadmium detector can be remarkably repaired, and the resistivity and the energy resolution of the detector are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of compound semiconductor crystal processing, and particularly relates to a repair method for a cadmium zinc telluride radiation detector with low energy resolution. Background Art

[0002] A cadmium zinc telluride (CdZnTe) radiation detector is a high-performance room-temperature semiconductor detector, which has advantages such as good room-temperature performance, fast response speed, high sensitivity, relatively high carrier mobility and large lifetime product. Therefore, cadmium zinc telluride radiation detectors are widely used in fields such as environmental monitoring, nuclear medicine, industrial non-destructive testing, security inspection, aerospace, astrophysics and high-energy physics.

[0003] However, due to the influence of the external environment (such as irradiation, high temperature, etc.) or the lack of strict control of the growth conditions during the crystal growth process, the detection performance of the detector deteriorates (the energy resolution decreases), and it loses its use value. Therefore, there is an urgent need to explore a method for repairing a cadmium zinc telluride detector with low energy resolution, repairing the detection material used, so that the detector can continue to serve.

[0004] Currently, the repair of detection materials mainly adopts annealing methods. For example, Literature 1 "K.H.Kim. The Effect of Low-Temperature Annealing on a CdZnTe Detector[J]. IEEE Transactions on Nuclear Science, 2016, 63(4): 2278-2282." reported that annealing cadmium zinc telluride crystals at 80-120 °C in air showed that the resistivity of the crystal increased, the leakage current decreased, but the energy resolution decreased. Literature 2 "W.J.Kim. Effect of Cd-annealing on the IR Transmittance of CdTe Wafers Grown by the Bridgman Method[J]. Journal of Crystal Growth. 1990, 104: 677-682." reported that the infrared transmittance of CdTe crystals increased monotonically with the extension of annealing time. After annealing in Cd atmosphere for 5 hours, the infrared transmittance of CdTe crystals increased to 65%, approaching the theoretical maximum transmittance, but it did not involve the improvement of detector performance. Literature 3 "Guo Xin. Interaction between Gas Atmosphere and CdZnTe Crystal during Annealing Process[M]. Xi'an: Northwestern Polytechnical University, 2015." reported that cadmium zinc telluride crystals were annealed at 700 °C in H2 atmosphere. After annealing, the infrared transmittance of the crystal decreased significantly, the resistivity decreased by one order of magnitude, and the leakage current of the crystal increased significantly. Moreover, the H2 atmosphere has potential safety hazards. There are many such literatures exploring annealing processes to improve crystal performance, but they all re-improve the performance of finished crystals and there is no method to repair cadmium zinc telluride crystals that are damaged during service and cause deterioration of performance (energy resolution is zero) or extremely poor performance (extremely low energy resolution) due to growth defects and other reasons.

[0005] In view of this, it is necessary to propose a repair method that can repair the performance of cadmium zinc telluride crystals and is relatively safe. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem that the detection performance of the detector deteriorates or is even completely damaged due to being damaged by the external environment during the service of existing cadmium zinc telluride crystals as detection materials, and to provide a repair method for cadmium zinc telluride radiation detectors with low energy resolution.

[0007] To achieve the above purpose, the technical solution provided by the present invention is:

[0008] A repair method for cadmium zinc telluride crystals with low energy resolution, characterized in that it includes the following steps:

[0009] S1. Pretreatment

[0010] Polish the low - energy - resolution cadmium zinc telluride (CZT) crystal that has been damaged (such as affected by irradiation during use) or is a defective product (such as having defects in crystal growth) to remove foreign matters such as the oxide layer on the crystal surface, the previously evaporated metal electrodes, and adhesives.

[0011] S2. Annealing

[0012] S21. Place the CZT crystal pretreated in S1 at the center of an annealing furnace with a uniform temperature field.

[0013] S22. Use a vacuum pump to evacuate the annealing furnace until the vacuum degree in the furnace is 10 Pa - 1.0×10 - 3 Pa.

[0014] S23. While closing the vacuum pump, introduce an inert gas into the annealing furnace to evacuate the air in the furnace as the annealing protective gas.

[0015] S24. Keep the temperature at 100 - 300 °C for heat preservation annealing for 5 - 15 h, where the heating rate is 1 - 15 °C / min.

[0016] S25. After the heat preservation ends, let the CZT crystal cool naturally to room temperature.

[0017] S3. Post - annealing treatment

[0018] Polish the CZT crystal annealed in S2 to remove the damaged layer formed on the surface after annealing, and obtain a repaired CZT crystal.

[0019] Furthermore, in S1 and S3, the specific polishing operation is as follows:

[0020] First, coarsely polish the crystal with a magnesium oxide grinding fluid, and then finely polish the crystal with a hydrogen peroxide - silica sol grinding fluid with a ratio of 1:1 until there are no visible scratches on the surface. After ultrasonic cleaning and nitrogen drying, chemically polish the crystal with a 2% by mass bromine - methanol solution to remove the oxide skin or damaged layer on the crystal surface.

[0021] Furthermore, S21 is specifically: Place the CZT crystal pretreated in S1 in a quartz boat, and then place the quartz boat at the center of the furnace tube of a tube - type annealing furnace. The heating elements in the tube - type annealing furnace are evenly distributed outside the furnace tube and parallel to the furnace tube to ensure the uniformity of the temperature field.

[0022] Furthermore, in S23, the inert gas is nitrogen with a flow rate of 30 - 150 mL / min.

[0023] Further, in order to improve the repair effect, in S24, the preferred temperature is 150 °C, the heat preservation time is 10 h, and the heating rate is 2 °C / min.

[0024] Meanwhile, based on the above repair method of cadmium telluride zinc crystals, the present invention provides a repair method for a cadmium telluride zinc radiation detector with low energy resolution, which is characterized by including the following steps:

[0025] 1) Remove the cadmium telluride zinc crystal in the detector;

[0026] 2) Repair the cadmium telluride zinc crystal according to the above repair method;

[0027] 3) Reassemble the detector.

[0028] Further, step 3) is specifically:

[0029] 3.1) Put the cadmium telluride zinc crystal repaired in step 2) into a vacuum evaporation coater;

[0030] 3.2) Under the pressure of 1×10 -3 -5×10 -3 Pa, use the vacuum evaporation coater to evaporate metal electrodes on both sides of the cadmium telluride zinc crystal;

[0031] 3.3) Use conductive glue to adhere the cadmium telluride zinc crystal obtained in step 3.2) to the PCB board, and assemble to obtain the repaired cadmium telluride zinc detector.

[0032] Further, in step 3.2), the metal electrode is Au.

[0033] The mechanism of the present invention:

[0034] After irradiation, a large number of intrinsic point defects exist in damaged or defective crystals, such as vacancies, interstitials, antisites, and defect complexes. These defects will be ionized to varying degrees, forming trapping or recombination centers that trap or recombine carriers, thereby shortening the effective drift length of carriers and limiting the mobility and lifetime of carriers. Under the process conditions of 100 - 300 °C, a holding time of 5 - 15 h, and a heating rate of 1 - 15 °C / min, annealing the irradiated-damaged or defective cadmium telluride crystals can effectively improve their resistivity and energy resolution. Within this temperature range, the atoms in the crystal have sufficient energy for diffusion and migration, and can effectively repair the point defects, dislocations, and other crystal defects generated by irradiation damage, thereby reducing the scattering and capture of carriers by defects, increasing the resistivity of the crystal, and at the same time avoiding excessive activation of atoms inside the crystal due to too high temperature, which may generate new defects or reactivate the repaired defects; while a holding time of 5 - 15 h can not only provide sufficient time for the repair of crystal defects and the diffusion of atoms, making the crystal structure tend to be stable and complete, but also avoid the excessive diffusion and aggregation of atoms inside the crystal due to too long time, which may form new defects or change the microstructure of the crystal, thereby ensuring the improvement of the crystal performance after annealing; a heating rate of 1 - 15 °C / min is relatively slow, which can not only effectively control the thermal stress in the crystal during annealing, avoid the generation of large thermal stress inside the crystal due to rapid heating, resulting in defects such as microcracks or dislocations, but also provide sufficient time and energy for the diffusion and migration of atoms, enabling the atoms to fully move to the appropriate positions for defect repair, and at the same time contributing to the gradual release of the internal stress of the crystal, avoiding the formation of defects due to stress concentration, thereby increasing the resistivity and energy resolution of the crystal. The three parameters of annealing temperature, holding time, and heating rate affect and restrict each other, jointly determining the annealing effect. Within the above annealing process range, the atomic structure and chemical bonds of cadmium telluride crystals can better adapt to this heat treatment process to achieve performance optimization; while beyond this range, it may damage the structural stability of the crystal, resulting in poor annealing effects.

[0035] Advantages of the present invention:

[0036] 1. The repair method of the present invention is simple and easy to operate, and the effect is outstanding. Compared with the existing repair methods of cadmium telluride radiation detectors, it can significantly repair the performance of cadmium telluride crystals, increase the resistivity and energy resolution of the detectors; it can be used to repair cadmium telluride detectors whose detection performance deteriorates after being damaged by the outside world during service and defective cadmium telluride crystals (collectively referred to as cadmium telluride crystals with low energy resolution), extend the service life of the detectors, and realize the effective utilization of defective products.

[0037] 2. The present invention uses an annealing furnace with a uniform temperature field (such as a tube annealing furnace) to slowly heat the cadmium telluride crystal to the set temperature in an inert gas atmosphere and then hold the temperature. After the heat preservation ends, the crystal is cooled to room temperature with the furnace. Compared with before annealing, the resistivity of the cadmium telluride detector is significantly increased, and the detector is more sensitive to 241 the response of Am@59.5keV γ-rays is more sensitive, and the energy resolution is significantly improved.

[0038] 3. The repair method of the present invention uses inert gas as the annealing atmosphere, with relatively high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram of the device of the present invention;

[0040] The reference numerals are as follows:

[0041] 1 - heating element, 2 - cadmium telluride crystal, 3 - quartz boat, 4 - vacuum pump;

[0042] Figure 2 is the I-V curve of the cadmium telluride detector before and after annealing in Example 1; a is the change diagram of the leakage current before and after annealing, and b is the change diagram of the resistivity before and after annealing;

[0043] Figure 3 is the γ-ray energy spectrum of the cadmium telluride detector before and after annealing in Example 1 ( 241 Am@59.5keV);

[0044] Figure 4 is the I-V curve of the cadmium telluride detector before and after annealing in Example 2; a is the change diagram of the leakage current before and after annealing, and b is the change diagram of the resistivity before and after annealing;

[0045] Figure 5 is the γ-ray energy spectrum of the cadmium telluride detector before and after annealing in Example 2 ( 241 Am@59.5keV).

[0046] Figure 6 is the I-V curve of the cadmium telluride detector before and after annealing in Example 3; a is the change diagram of the leakage current before and after annealing, and b is the change diagram of the resistivity before and after annealing;

[0047] Figure 7 is the γ-ray energy spectrum of the cadmium telluride detector before and after annealing in Example 3 ( 241 Am@59.5keV);

[0048] Figure 8 is the I-V curve of the cadmium telluride detector before and after annealing in Comparative Example 1; a is the change diagram of the leakage current before and after annealing, and b is the change diagram of the resistivity before and after annealing;

[0049] Figure 9I-V curves of CdZnTe detectors before and after annealing for Comparative Example 2; a is the change diagram of leakage current before and after annealing, and b is the change diagram of resistivity before and after annealing. Detailed implementation manners

[0050] The following further describes the content of the present invention in detail with reference to the drawings and specific embodiments:

[0051] Example 1

[0052] A repair method for a low energy resolution CdZnTe radiation detector includes the following steps:

[0053] S1. Pretreatment of CdZnTe crystal:

[0054] Perform a polishing operation on the damaged CdZnTe crystal (without energy resolution) in the detector. First, use magnesium oxide grinding fluid to perform rough polishing on the crystal (each surface is rough polished 100 - 150 times), and then use a hydrogen peroxide - silica sol grinding fluid with a ratio of 1:1 to perform fine polishing on the crystal. After fine polishing, there are no visible scratches on the crystal surface. After ultrasonic cleaning and nitrogen drying, use a 2% bromine - methanol solution to perform chemical polishing on the sample to remove the damaged layer on the crystal surface;

[0055] S2. Annealing of CdZnTe crystal:

[0056] Perform annealing treatment on the CdZnTe crystal pretreated in S1. Place the CdZnTe crystal in a quartz boat with dimensions of 20mm×10mm×2mm, and then place the quartz boat in the center of the furnace tube of a tube - type annealing furnace. For the used tube - type annealing furnace, the heating elements are parallel to the furnace tube and are evenly distributed outside the furnace tube to ensure the uniformity of the temperature field. Use a vacuum pump to perform a vacuuming operation on the tube - type annealing furnace until the vacuum degree in the tube - type annealing furnace is 1.0×10 -3 Pa. While closing the vacuum pump, introduce nitrogen into the tube - type annealing furnace (flow rate is 30mL / min). Set the annealing process parameters, the heating rate is 1℃ / min, the target temperature is 300℃, and keep the temperature for 5 hours at the target temperature. After the heat preservation ends, the CdZnTe crystal naturally cools down to room temperature;

[0057] S3. Post - treatment after annealing of CdZnTe crystal:

[0058] Perform a polishing operation on the CdZnTe crystal annealed in step S2. First, use magnesium oxide grinding fluid to perform rough polishing on the crystal (each surface is rough polished 100 - 150 times), and then use a hydrogen peroxide - silica sol grinding fluid with a ratio of 1:1 to perform fine polishing on the crystal. After fine polishing, there are no visible scratches on the crystal surface. After ultrasonic cleaning and nitrogen drying, use a 2% bromine - methanol solution to perform chemical polishing on the sample to remove the damaged layer on the crystal surface;

[0059] S4. Detector preparation:

[0060] Put the cadmium telluride (CdTe) crystal after S3 polishing treatment into a vacuum evaporation coater. Under a pressure of 5×10 -3 Pa, use the vacuum evaporation coater to evaporate Au electrodes on both sides of the CdTe crystal. Adhere the CdTe crystal with evaporated Au electrodes to a PBC board using conductive adhesive to obtain a repaired CdTe detector.

[0061] The repaired CdTe detector in this embodiment consists of Figure 2 From the I-V curve, it can be seen that its resistivity increases significantly, from 1.52×10 7 Ω·cm before annealing to 1.93×10 10 Ω·cm, and the leakage current decreases significantly. The leakage current at 100V decreases from 9.06×10 -6 A before annealing to 3.23×10 -9 A. From Figure 3 the energy spectrum, it can be seen that the detection performance of the detector after annealing is significantly improved. Before annealing, due to the excessive leakage current, the detection spectral peak of γ-rays is covered by the noise formed by the leakage current, while the energy resolution at 500V after annealing reaches 8.37%; it can be seen that the detector in this embodiment is successfully repaired.

[0062] Example 2

[0063] A method for repairing a cadmium telluride radiation detector with low energy resolution, comprising the following steps:

[0064] S1. Pretreatment of the cadmium telluride crystal:

[0065] Perform a polishing operation on the damaged cadmium telluride crystal (without energy resolution) in the detector. First, use a magnesium oxide grinding fluid to perform rough polishing on the crystal (rough polish each surface 100 - 150 times), and then use a hydrogen peroxide-silica sol grinding fluid with a ratio of 1:1 to perform fine polishing on the crystal. After fine polishing, there are no visible scratches on the crystal surface. After ultrasonic cleaning and nitrogen drying, use a 2% bromine-methanol solution to chemically polish the sample to remove the damaged layer on the crystal surface;

[0066] S2. Annealing of the cadmium telluride crystal:

[0067] Anneal the cadmium telluride (CdTe) crystal after pre-treatment in S1. Place the CdTe crystal in a quartz boat with dimensions of 20 mm × 10 mm × 2 mm, and then place the quartz boat in the center of the furnace tube of a tube annealing furnace. For the used tube annealing furnace, the heating elements are parallel to the furnace tube and evenly distributed outside the furnace tube to ensure the uniformity of the temperature field. Use a vacuum pump to evacuate the tube annealing furnace until the vacuum degree inside the furnace reaches 10 Pa. While closing the vacuum pump, introduce nitrogen gas (flow rate: 100 mL / min) into the tube annealing furnace. Set the annealing process parameters: the heating rate is 15 °C / min, the target temperature is 100 °C, and keep it at the target temperature for 15 hours. After the insulation ends, let the CdTe crystal cool down naturally to room temperature;

[0068] S3. Post-treatment of the annealed cadmium telluride crystal:

[0069] Perform a polishing operation on the annealed cadmium telluride crystal in step S2. First, rough polish the crystal with a magnesium oxide grinding liquid (each face is rough polished 100 - 150 times), and then fine polish the crystal with a hydrogen peroxide-silica sol grinding liquid with a ratio of 1:1. After fine polishing, there are no visible scratches on the crystal surface. After ultrasonic cleaning and nitrogen drying, use a 2% bromo-methanol solution to chemically polish the sample to remove the damaged layer on the crystal surface;

[0070] S4. Preparation of the detector:

[0071] Place the cadmium telluride crystal after polishing treatment in S3 into a vacuum evaporation machine, and deposit Au electrodes on both sides of the cadmium telluride crystal under a pressure of 5×10 -3 Pa using the vacuum evaporation machine. Adhere the cadmium telluride crystal with deposited Au electrodes to a PBC board with conductive glue to obtain a repaired cadmium telluride detector.

[0072] The repaired cadmium telluride detector in this embodiment Figure 4 From the I-V curve, it can be seen that its resistivity increases significantly, from 1.67×10 7 Ω·cm before annealing to 6.16×10 9 Ω·cm, and the leakage current decreases significantly. The leakage current at 100 V decreases from 3.91×10 -5 A before annealing to 3.85×10 -9 A. From the Figure 5 energy spectrum, it can be seen that the detection performance of the detector after annealing is significantly improved. Before annealing, due to excessive leakage current, the detection spectrum peak of γ-rays was covered by the noise formed by the leakage current, while the energy resolution at 500 V after annealing reached 7.35%; it can be seen that the detector in this embodiment is successfully repaired.

[0073] Example 3

[0074] Repair method for a low energy resolution cadmium zinc telluride radiation detector, comprising the following steps:

[0075] S1. Pretreatment of cadmium zinc telluride crystal:

[0076] Perform a polishing operation on the damaged cadmium zinc telluride crystal (without energy resolution) in the detector. First, use magnesium oxide grinding fluid to coarsely polish the crystal (coarsely polish each surface 100 - 150 times), and then use a hydrogen peroxide - silica sol grinding fluid with a ratio of 1:1 to finely polish the crystal. After fine polishing, there are no visible scratches on the crystal surface. After ultrasonic cleaning and nitrogen drying, use a 2% bromine - methanol solution to chemically polish the sample to remove the damaged layer on the crystal surface;

[0077] S2. Annealing of cadmium zinc telluride crystal:

[0078] Perform annealing treatment on the cadmium zinc telluride crystal pretreated in S1. Place the cadmium zinc telluride crystal into a quartz boat with dimensions of 20mm×10mm×2mm, and then place the quartz boat in the center of the furnace tube of a tube - type annealing furnace. For the used tube - type annealing furnace, the heating elements are parallel to the furnace tube and are evenly distributed outside the furnace tube to ensure the uniformity of the temperature field. Use a vacuum pump to evacuate the tube - type annealing furnace until the vacuum degree in the tube - type annealing furnace is 1.0×10 -3 Pa. While closing the vacuum pump, introduce nitrogen into the tube - type annealing furnace (flow rate is 150 mL / min). Set the annealing process parameters, the heating rate is 2℃ / min, the target temperature is 150℃, and keep it at the target temperature for 10 hours. After the insulation ends, the cadmium zinc telluride crystal naturally cools down to room temperature;

[0079] S3. Post - treatment after annealing of cadmium zinc telluride crystal:

[0080] Perform a polishing operation on the cadmium zinc telluride crystal annealed in step S2. First, use magnesium oxide grinding fluid to coarsely polish the crystal (coarsely polish each surface 100 - 150 times), and then use a hydrogen peroxide - silica sol grinding fluid with a ratio of 1:1 to finely polish the crystal. After fine polishing, there are no visible scratches on the crystal surface. After ultrasonic cleaning and nitrogen drying, use a 2% bromine - methanol solution to chemically polish the sample to remove the damaged layer on the crystal surface;

[0081] S4. Detector preparation:

[0082] Put the cadmium zinc telluride crystal polished in S3 into a vacuum evaporation machine, and under a pressure of 5×10 -3 Pa, use the vacuum evaporation machine to evaporate Au electrodes on both sides of the cadmium zinc telluride crystal. Use conductive glue to adhere the cadmium zinc telluride crystal with evaporated Au electrodes to a PBC board to obtain a repaired cadmium zinc telluride detector.

[0083] The repaired cadmium zinc telluride detector in this embodiment is composed of Figure 6It can be seen from the I-V curve that its resistivity increases significantly, from 1.36×10 7 Ω·cm before annealing to 5.53×10 10 Ω·cm. The leakage current decreases significantly. The leakage current at 100V decreases from 2.50×10 -5 A before annealing to 4.90×10 -9 A. From Figure 7 the energy spectrum, it can be seen that the detection performance of the detector is significantly improved after annealing. Before annealing, due to the excessive leakage current, the detection spectrum peak of γ-rays is covered by the noise formed by the leakage current. After annealing, the energy resolution at 500V reaches 12.52%. It can be seen that in this embodiment, the detector is successfully repaired and the repair effect is the best.

[0084] Through Examples 1-3, the repair effect of the damaged cadmium zinc telluride crystal (without energy resolution) in the detector can be undoubtedly determined. This method must be applicable to the repair of defective cadmium zinc telluride crystals (with extremely low energy resolution). This has also been verified by experiments. After annealing the defective cadmium zinc telluride crystals using this method, their performance is significantly improved. For the detector made of the repaired cadmium zinc telluride crystal, its resistivity, leakage current, and energy resolution can all meet the service requirements.

[0085] Comparative Example 1

[0086] The difference from Example 3 is that:

[0087] In the annealing process parameters of S2, the heating rate is 1℃ / min, the target temperature is 80℃, and it is kept at the target temperature for 20 hours.

[0088] This comparative example obtains an annealed cadmium zinc telluride detector. From Figure 8 the I-V curve, it can be seen that the resistivity of the detector before and after annealing changes little, both in the order of 10 7 Ω·cm, and the leakage current changes little. The leakage current at 100V is both in the order of 10 -6 Ω·cm. Due to the excessive leakage current, the detection spectrum peaks of the energy resolution before and after annealing for γ-rays are covered by the noise formed by the leakage current. Under this condition, the detection performance of the detector before and after annealing has not been improved.

[0089] Comparative Example 2

[0090] The difference from Example 3 is that:

[0091] In the annealing process parameters of S2, the heating rate is 17℃ / min, the target temperature is 350℃, and it is kept at the target temperature for 4 hours.

[0092] This comparative example obtains an annealed cadmium zinc telluride detector. From Figure 9It can be seen from the I-V curve that the resistivity of the detector before and after annealing changes little, both in the order of 10 7 Ω·cm, and the leakage current changes little. The leakage current at 100V is all in the order of 10 -6 Ω·cm. Due to the excessive leakage current, the detection spectral peaks of γ-rays of the energy resolution before and after annealing are covered by the noise formed by the leakage current. Under this condition, the detection performance of the detector before and after annealing has not been improved.

[0093] It can be seen from the comparison between the examples and the comparative examples that annealing the damaged or defective cadmium telluride crystal outside the temperature range of 100-300 °C and the holding time range of 5-15 h cannot achieve effective repair. Only by adopting the repair method of the present invention can the resistivity and energy resolution of the damaged detector be improved simultaneously, the service life of the detector be extended, and the detector can continue to serve.

[0094] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or replacements, and these modifications or replacements should be covered within the protection scope of the present invention.

Claims

1. A method for repairing a cadmium zinc telluride crystal with low energy resolution, characterized in that It includes the following steps: S1. Pretreatment Polish the damaged or defective cadmium telluride (CdTe) crystal. S2. Annealing S21. Place the CdTe crystal pretreated in S1 at the center of an annealing furnace with a uniform temperature field. S22. Use a vacuum pump to evacuate the annealing furnace until the vacuum degree inside the furnace is 10 Pa - 1.0×10 -3 Pa; S23. While closing the vacuum pump, introduce an inert gas into the annealing furnace. S24. Keep the temperature at 100 - 300 °C for heat preservation annealing for 5 - 15 h, where the heating rate is 1 - 15 °C / min. S25. After the heat preservation ends, let the CdTe crystal cool naturally to room temperature. S3. Post - annealing treatment Polish the CdTe crystal annealed in S2 to obtain a repaired CdTe crystal.

2. The repair method of the cadmium zinc telluride crystal with low energy resolution according to claim 1, wherein, In S1 and S3, the specific polishing operation is as follows: First, rough - polish the crystal with a magnesium oxide grinding liquid, and then fine - polish the crystal with a hydrogen peroxide - silica sol grinding liquid with a ratio of 1:1 until there are no visible scratches on the surface. After ultrasonic cleaning and nitrogen drying, chemically polish the crystal with a 2% by mass bromine - methanol solution.

3. The repair method of the cadmium zinc telluride crystal with low energy resolution according to claim 1 or 2, characterized in that, S21 is specifically: Place the CdTe crystal pretreated in S1 into a quartz boat, and then place the quartz boat at the center of the furnace tube of a tube - type annealing furnace.

4. The repair method of the low - energy - resolution cadmium telluride crystal according to claim 3, wherein: In S23, the inert gas is nitrogen with a flow rate of 30 - 150 mL / min.

5. The repair method of the low - energy - resolution cadmium telluride crystal according to claim 4, wherein: In S24, the temperature is 150 °C, the heat - preservation time is 10 h, and the heating rate is 2 °C / min.

6. Method for repairing a cadmium zinc telluride radiation detector with low energy resolution, characterized in that, It includes the following steps: 1) Remove the CdTe crystal in the detector; 2) Repair the CdTe crystal according to the repair method described in any one of claims 1 - 5; 3) Re - assemble the detector.

7. The repair method of the low energy resolution cadmium zinc telluride radiation detector according to claim 6, characterized in that, Step 3) is specifically: 3.1) Place the CdTe crystal repaired in step 2) into a vacuum evaporation machine; 3.2) At a pressure of 1×10 -3 - 5×10 -3 Pa, a metal electrode is vapor-deposited on both sides of the cadmium telluride zinc crystal using a vacuum evaporation coater; 3.3) Use conductive glue to adhere the CdTe crystal obtained in step 3.2) to the PCB board to assemble and manufacture a repaired CdTe detector.

8. The repair method of the low - energy - resolution cadmium telluride radiation detector according to claim 7, wherein: In step 3.2), the metal electrode is Au.

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