CsPbBr3 single-crystal-based gamma-ray energy spectrum detector and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor radiation detection, in particular to a structure and a preparation method of a CsPbBr3 single crystal based gamma ray energy spectrum detector. The structure of the CsPbBr3 single crystal-based gamma ray energy spectrum detector sequentially comprises a first metal electrode layer, a first PbO layer, a CsPbBr3 single crystal layer, a second PbO layer and a second metal electrode layer from top to bottom. The PbO layer is obtained by irradiating the surface of a single crystal with high-pulse energy density ultraviolet laser; the first metal electrode layer and the second metal electrode layer are deposited on the outer side of the PbO layer through vacuum thermal evaporation. Due to the existence of the PbO layer on the surface of the CsPbBr3 single crystal, the surface state of the surface of the single crystal can be weakened, so that the non-radiative recombination of photon-generated carriers is reduced; due to the existence of PbO, the work function of the surface of the CsPbBr3 single crystal can be increased, so that a Schottky barrier formed with an indium electrode is improved, and the energy spectrum resolution of the device to gamma rays is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor-based gamma-ray detectors, and in particular relates to the structure of a CsPbBr3 single crystal-based gamma-ray energy spectrum detector and a method for preparing the detector. Background Art

[0002] Radiation detectors based on compound semiconductor materials have attracted great attention in the application of material analysis, environmental monitoring and medical imaging. Compared with early scintillator radiation detectors, semiconductor radiation detectors have significant advantages, including higher energy resolution, faster response time and smaller size. For example, CdZnTe (CZT), CdTe, TlBr, etc. At present, semiconductor-based gamma-ray detectors prepared based on CZT have excellent detection performance, for example, collecting 137 When the energy spectrum of Cs radiation source is measured, the highest resolution of 662keV photons is better than 1%. In addition, compared with high-purity silicon and high-purity germanium with lower band gap, this type of compound semiconductor does not require additional refrigeration facilities and has significant advantages in device size. However, the high preparation cost of this type of semiconductor and its stability at high temperature affect the large-scale application of this type of device.

[0003] In recent years, perovskite materials have gained great attention in the fields of solar cells, photodetectors, LEDs, etc. due to their excellent properties such as adjustable band gap, high absorption coefficient, high atomic number, high carrier mobility, etc. Current research on perovskite materials has found that this material can be synthesized by a variety of methods. For example, perovskite films are prepared by spin coating, perovskite single crystals are grown by solution method, and perovskite single crystals are grown by melt method. CsPbBr3 crystal material has excellent performance, and this semiconductor material can be synthesized by a variety of methods, such as solution method, melt method, etc. These synthesis processes are currently relatively mature and provide a basis for semiconductor radiation detection. He Yihui et al., using a CsPbBr3 single crystal-based gamma-ray detector prepared by the melt method, detected 662keV 137 Cs obtained a spectral resolution of 1.4%. Huang Jinsong et al. used a CsPbBr3 single crystal gamma-ray detector prepared by solution method to detect 662keV 137 Cs obtained an energy spectrum resolution of 5.4%. Since the grown single crystal needs to be processed by polishing, grinding and other treatment methods, this will inevitably lead to some surface defects on the surface. In addition, during the growth process of CsPbBr3 single crystal, due to changes in the environment, the growth rate will also change, resulting in the existence of some defects. These defects will cause surface states on the surface of the single crystal, which will enhance the non-radiative recombination of photogenerated carriers and thus affect the performance of the device.

[0004] In order to solve the defects at the interface, many researchers have proposed a variety of methods. The traditional method is to use chemical reagents to passivate the defects on the semiconductor surface, such as Lewis acid, Lewis base, high molecular polymer, phosphate, etc. Although these chemical reagents have been proven to passivate defects, the use of chemical reagents will introduce additional chemical elements. The use of chemical reagents will also make the process complicated. Some chemical reagents have certain biological and environmental toxicity. Summary of the invention

[0005] One of the purposes of the present invention is to provide a CsPbBr3 single crystal based gamma-ray energy spectrum detector, by adding a layer of PbO on the upper and lower surfaces of the semiconductor in the original metal electrode / semiconductor / metal electrode, thereby reducing the adverse effects of the surface state of the single crystal on the interface between the semiconductor and the electrode of the device and reducing the non-radiative recombination of photogenerated carriers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which structurally includes from top to bottom: a first metal electrode layer, a first PbO layer, a CsPbBr3 single crystal layer, a second PbO layer, and a second metal electrode layer.

[0007] As a further improvement of CsPbBr3 single crystal based gamma ray energy spectrum detector:

[0008] Preferably, the first metal electrode layer has a thickness of 10-100 nm and an area smaller than the first PbO layer. The first metal electrode layer is a low work function metal electrode and can form a Schottky junction with the CsPbBr3 single crystal.

[0009] Preferably, the second metal electrode layer 5 has a thickness of 10-100 nm, an area greater than or equal to that of the first metal electrode layer 1 , and forms a counter electrode with the first metal electrode layer 1 .

[0010] Preferably, the first metal electrode layer is an indium electrode (In), a gallium electrode (Ga) or a gallium-indium eutectic electrode (EGaIn), and the second metal electrode layer is a gold electrode (Au), a platinum electrode (Pt) or a silver electrode (Ag).

[0011] Preferably, the thickness of the CsPbBr3 single crystal layer is 1-10 mm.

[0012] Preferably, the thickness of the first PbO layer and the second PbO layer are both 5-100 nm.

[0013] The second object of the present invention is to provide a method for preparing a CsPbBr3 single crystal based gamma-ray energy spectrum detector as described in any one of the above, comprising the following steps:

[0014] S1, cutting, grinding and polishing the CsPbBr3 single crystal to obtain a CsPbBr3 single crystal layer for absorbing gamma rays;

[0015] S2, preparing a first PbO layer and a second PbO layer on the upper and lower surfaces of the CsPbBr3 single crystal layer respectively;

[0016] S3, preparing a first metal electrode layer on the surface of the first PbO layer and preparing a second metal electrode layer on the surface of the second PbO layer by vacuum evaporation or coating;

[0017] S4. Use conductive silver paste and wires to connect the first metal electrode layer and the second metal electrode layer in the structure of step S3 to the electrodes of the PCB board respectively, so as to prepare a CsPbBr3 single crystal-based gamma-ray energy spectrum detector.

[0018] As a further improvement of the preparation method of CsPbBr3 single crystal based gamma ray energy spectrum detector:

[0019] Preferably, the CsPbBr3 single crystal described in step S1 is prepared by a solution method or a melt method; the preparation method of the first PbO layer and the second PbO layer in step S2 is one of high pulse energy density ultraviolet laser surface irradiation, oxygen plasma treatment, and chemical vapor deposition.

[0020] Preferably, the preparation method of the first PbO layer 2 and the second PbO layer 4 in step S1 is as follows: by using a KrF excimer laser, the energy density of the laser is set to 20-60 mJ / cm 2 The laser operating frequency is set to 60 Hz, the pulse number is 20-200, and the upper and lower surfaces of the CsPbBr3 single crystal layer 3 are irradiated respectively to generate the first PbO layer 2 and the second PbO layer 4 in sequence.

[0021] Preferably, in step S3, the first metal electrode layer is prepared by vacuum evaporation method, and the pressure in the deposition chamber is not higher than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The deposition time is 1-50 minutes; the pressure of the second metal electrode layer in the deposition chamber is not higher than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The deposition time was 1–50 minutes.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The present invention provides a CsPbBr3 single crystal-based gamma-ray energy spectrum detector structure. On the basis of the original metal electrode / semiconductor (such as CsPbBr3 single crystal) / metal electrode, a PbO layer is prepared on the upper and lower surfaces of the semiconductor respectively. The PbO layer is used to reduce the surface state of the single crystal, thereby improving the collection of photogenerated carriers and improving the surface work function of the single crystal, which can reduce the adverse effects of the surface state of the single crystal on the interface between the semiconductor and the electrode of the device and reduce the non-radiative recombination of photogenerated carriers.

[0024] 2) The present invention uses PbO to improve the work function of the surface of the CsPbBr3 single crystal, and uses a metal with a low work function as an electrode to form a Schottky contact therewith. The work function of the surface of the CsPbBr3 single crystal is improved, which is beneficial to the increase of the Schottky barrier, can promote the stability of the device under high voltage and the collection of photogenerated carriers, and is beneficial to the performance improvement of the device.

[0025] 3) The present invention also provides a method for preparing a CsPbBr3 single crystal-based gamma-ray energy spectrum detector, wherein a first PbO layer and a second PbO layer are respectively prepared on the upper surface of the CsPbBr3 single crystal. The preparation of the PbO layer can be prepared by irradiating the surface with a high pulse energy density ultraviolet laser, wherein the laser decomposes the chemical bonds of CsPbBr3 on the surface of the single crystal, and then reacts with oxygen in the air to form a PbO layer; it can also be prepared by oxygen plasma treatment, wherein high-energy oxygen plasma bombards the surface of the single crystal, breaks the chemical bonds of CsPbBr3, and reacts with Pb on the surface to form a PbO layer; it can also be prepared by chemical vapor deposition, wherein Pb and O2 are used as reactants, which evaporate into a gaseous state at a high temperature, and finally react on the surface of the single crystal to form PbO. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural diagram of the CsPbBr3 single crystal based gamma-ray energy spectrum detector in Example 1;

[0027] Figure 2 The CsPbBr3 single crystal based detector with In / CsPbBr3 single crystal layer / Au structure obtained in the comparative example 137 Cs energy spectrum.

[0028] Figure 3 The CsPbBr3 single crystal based gamma ray energy spectrum detector with the In / PbO / CsPbBr3 single crystal layer / PbO / Au structure obtained in Example 1 137 Cs energy spectrum.

[0029] The meanings of the symbols in the accompanying drawings are as follows:

[0030] 1. First metal electrode layer; 2. First PbO layer; 3. CsPbBr3 single crystal layer; 4. Second PbO layer; 5. Second metal electrode layer. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a structure of a CsPbBr3 single crystal based gamma ray energy spectrum detector, as shown in the attached Figure 1 As shown, the structure includes from top to bottom: a first metal electrode layer 1, a first PbO layer 2, a CsPbBr3 single crystal layer 3, a second PbO layer 4, and a second metal electrode layer 5;

[0034] The thickness of the first metal electrode layer 1 is 10-100 nm, and its area is smaller than the first PbO layer 2. The first metal electrode layer 1 is a low work function metal electrode, and can form a Schottky junction with the CsPbBr3 single crystal. Specifically, the first metal electrode layer 1 is an indium electrode (In), a gallium electrode (Ga), or a gallium-indium eutectic electrode (EGaIn).

[0035] The thickness of the first PbO layer 2 and the second PbO layer 4 are both 5-100 nm;

[0036] The thickness of the CsPbBr3 single crystal layer 3 is 1-10 mm;

[0037] The second metal electrode layer 5 has a thickness of 10-100 nm, an area greater than or equal to the first metal electrode layer 1 and forms a counter electrode with the first metal electrode layer 1; specifically, the second metal electrode layer 5 is a gold electrode (Au), a platinum electrode (Pt) or a silver electrode (Ag).

[0038] Comparative Example 1

[0039] This embodiment provides a method for preparing an In / CsPbBr3 single crystal layer / Au structure detector, which specifically includes the following steps:

[0040] (1) After cutting a CsPbBr3 single crystal grown by an inversion growth method (solution method), the single crystal was polished using sandpapers of 5000 mesh, 7000 mesh, and 10000 mesh, respectively, to a thickness slightly greater than 2 mm, and then the single crystal was polished using a polishing liquid configured with 500 nm Al2O3 to a thickness of 2 mm, as a CsPbBr3 single crystal layer 3 that absorbs gamma rays;

[0041] (2) A first metal electrode layer 1 is deposited on the upper surface of the CsPbBr3 single crystal layer 3 by vacuum evaporation. The first metal electrode layer 1 is an In electrode. The vacuum thermal evaporation deposition process is performed under a pressure in the deposition chamber of no more than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The thickness of the first metal electrode layer 1 is 50 nm;

[0042] The second metal electrode layer 5 is deposited on the lower surface of the CsPbBr3 single crystal layer 3 by vacuum evaporation method. The second metal electrode layer 5 is an Au electrode. The vacuum thermal evaporation deposition process is carried out under the pressure of no more than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The thickness of the second metal electrode layer 5 is 50 nm;

[0043] (3) Using conductive silver paste and wires, the first metal electrode layer 1 and the second metal electrode layer 5 in the structure obtained in the above steps are connected to the electrodes of the PCB board respectively, to prepare a CsPbBr3 single crystal based detector, which is recorded as In / CsPbBr3 single crystal layer / Au structure detector.

[0044] Example 2

[0045] This embodiment provides a method for preparing a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which specifically includes the following steps:

[0046] (1) After the CsPbBr3 single crystal grown by the inversion growth method is cut, it is polished with sandpapers of 5000 mesh, 7000 mesh, and 10000 mesh respectively to a thickness slightly higher than 2 mm, and then the single crystal is polished with a polishing liquid configured with 500 nm Al2O3 to a thickness of 2 mm, as the CsPbBr3 single crystal layer 3 that absorbs gamma rays;

[0047] (2) Use a KrF excimer laser and set the laser energy density to 40 mJ / cm 2 The laser operating frequency is set to 1 Hz, the number of pulses is 50, and the upper and lower surfaces of the CsPbBr3 single crystal layer 3 are irradiated respectively, and the first PbO layer 2 and the second PbO layer 4 are sequentially generated, with thicknesses of 50 nm and 50 nm respectively;

[0048] (3) A first metal electrode layer 1 is deposited on the surface of the first PbO layer 2 by vacuum evaporation method. The area of ​​the first metal electrode layer 1 is smaller than that of the first PbO layer 2. The first metal electrode layer 1 is an In electrode. The vacuum thermal evaporation deposition process is performed under a pressure in the deposition chamber of no more than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The thickness of the first metal electrode layer 1 is 50 nm;

[0049] The second metal electrode layer 5 is deposited on the surface of the second PbO layer 4 by vacuum evaporation method. The second metal electrode layer 5 is an Au electrode. The vacuum thermal evaporation deposition process is performed under a pressure in the deposition chamber of no more than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The second metal electrode layer 5 has a thickness of 50 nm, an area greater than or equal to the first metal electrode layer 1 and forms a counter electrode with the first metal electrode layer 1;

[0050] (4) Using conductive silver paste and wires, the first metal electrode layer 1 and the second metal electrode layer 5 in the structure obtained in the above steps are connected to the electrodes of the PCB board respectively, to prepare a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which is recorded as In / PbO / CsPbBr3 single crystal layer / PbO / Au structure detector.

[0051] Example 3

[0052] This embodiment provides a method for preparing a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which specifically includes the following steps:

[0053] (1) After the CsPbBr3 single crystal grown by the inversion growth method is cut, it is polished with sandpapers of 5000 mesh, 7000 mesh, and 10000 mesh respectively to a thickness slightly higher than 1 mm, and then the single crystal is polished with a polishing liquid configured with 500 nm Al2O3 to a thickness of 1 mm, as the CsPbBr3 single crystal layer 3 that absorbs gamma rays;

[0054] (2) Use a KrF excimer laser and set the laser energy density to 60 mJ / cm 2 The laser operating frequency is set to 60 Hz, the number of pulses is 20, and the upper and lower surfaces of the CsPbBr3 single crystal layer 3 are irradiated respectively, and the first PbO layer 2 and the second PbO layer 4 are sequentially generated, with thicknesses of 5 nm and 5 nm respectively;

[0055] (3) using a coating method, a liquid gallium material is applied on the surface of the first PbO layer 2 using a brush as the first metal electrode layer 1, the area of ​​the first metal electrode layer 1 is smaller than the first PbO layer 2, and the thickness of the first metal electrode layer 1 is 10 nm;

[0056] The second metal electrode layer 5 is deposited on the surface of the second PbO layer 4 by vacuum evaporation method. The second metal electrode layer 5 is a platinum electrode. The vacuum thermal evaporation deposition process is performed at a pressure in the deposition chamber of no more than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The second metal electrode layer 5 has a thickness of 10 nm, an area greater than or equal to the first metal electrode layer 1 and forms a counter electrode with the first metal electrode layer 1;

[0057] (4) Using conductive silver paste and wires, the first metal electrode layer 1 and the second metal electrode layer 5 in the structure obtained in the above steps are connected to the electrodes of the PCB board respectively, to prepare a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which is denoted as Ga / PbO / CsPbBr3 single crystal layer / PbO / Pt structure detector.

[0058] Example 4

[0059] This embodiment provides a method for preparing a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which specifically includes the following steps:

[0060] (1) After the CsPbBr3 single crystal grown by the inversion growth method is cut, it is polished with sandpapers of 5000 mesh, 7000 mesh, and 10000 mesh respectively to a thickness slightly higher than 10 mm, and then the single crystal is polished with a polishing liquid configured with 500 nm Al2O3 to a thickness of 10 mm, as the CsPbBr3 single crystal layer 3 that absorbs gamma rays;

[0061] (2) Use a KrF excimer laser and set the laser energy density to 20 mJ / cm 2 The laser operating frequency is set to 100 Hz, the number of pulses is 200, and the upper and lower surfaces of the CsPbBr3 single crystal layer 3 are irradiated respectively, and the first PbO layer 2 and the second PbO layer 4 are sequentially generated, with thicknesses of 100 nm and 100 nm respectively;

[0062] (3) using a coating method, a liquid gallium-indium eutectic material is applied on the surface of the first PbO layer 2 using a brush as the first metal electrode layer 1, the area of ​​the first metal electrode layer 1 is smaller than the first PbO layer 2, and the thickness of the first metal electrode layer 1 is 100 nm;

[0063] The second metal electrode layer 5 is deposited on the surface of the second PbO layer 4 by vacuum evaporation method. The second metal electrode layer 5 is a silver electrode. The vacuum thermal evaporation deposition process is performed under a pressure in the deposition chamber of no more than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The second metal electrode layer 5 has a thickness of 100 nm, an area greater than or equal to that of the first metal electrode layer 1 and forms a counter electrode with the first metal electrode layer 1;

[0064] (4) Using conductive silver paste and wires, the first metal electrode layer 1 and the second metal electrode layer 5 in the structure obtained in the above steps are connected to the electrodes of the PCB board respectively, to prepare a CsPbBr3 single crystal based gamma-ray energy spectrum detector, which is denoted as EGaIn / PbO / CsPbBr3 single crystal layer / PbO / Ag structure detector.

[0065] Comparative Example 2

[0066] This comparative example provides a method for preparing a CsPbBr3 single crystal-based gamma-ray energy spectrum detector. The specific steps refer to Example 2, except that: in step (2), one surface of the CsPbBr3 single crystal layer 3 is irradiated to generate a first PbO layer 2; in step (3), a first metal electrode layer 1 is deposited on the surface of the first PbO layer 2, and a second metal electrode layer 5 is directly deposited on the other surface of the CsPbBr3 single crystal layer 3. Finally, an In / PbO / CsPbBr3 single crystal layer / Au structure detector is obtained.

[0067] Comparative Example 3

[0068] This comparative example provides a method for preparing a CsPbBr3 single crystal-based gamma-ray energy spectrum detector. The specific steps refer to Example 2, except that: in step (2), one surface of the CsPbBr3 single crystal layer 3 is irradiated to generate a second PbO layer 4; in step (3), a first metal electrode layer 1 is directly deposited on the other surface of the CsPbBr3 single crystal layer 3, and a second metal electrode layer 5 is deposited on the surface of the second PbO layer 4. Finally, an In / CsPbBr3 single crystal layer / PbO / Au structure detector is obtained.

[0069] The CsPbBr3 single crystal based detectors prepared in Examples 2-4 and Comparative Examples 1-3 were respectively 137 Cs energy spectrum test. The energy spectrum was recorded by a system consisting of a MA-01A charge-sensitive preamplifier, a DPU-1000-01 high-voltage power supply, and an MCA-01 multi-channel analyzer (Shaanxi Ditech New Materials Co., Ltd.), and the test conditions were: electric field strength (200 V / mm), acquisition time (300 s), rise time (2 μs), and gain (2).

[0070] Figure 2 The CsPbBr3 single crystal based detector with the In / CsPbBr3 single crystal layer / Au structure obtained in Comparative Example 1 was used. 137 Cs energy spectrum. Figure 2 It can be seen that the detector with this structure is very sensitive to 662keV 137 The energy resolution of Cs is 15.8%. Similarly, the detector of Comparative Example 2 with In / PbO / CsPbBr3 single crystal layer / Au structure is 662keV 137The energy resolution of Cs is 9.38%; Comparative Example 3 has a detector with an In / CsPbBr3 single crystal layer / PbO / Au structure for 662keV 137 The Cs energy resolution is 11.26%.

[0071] Figure 3 The CsPbBr3 single crystal based gamma ray energy spectrum detector obtained in Example 2 137 Energy spectrum of Cs. Figure 3 It can be seen that the detector with In / PbO / CsPbBr3 single crystal layer / PbO / Au structure is sensitive to 662keV 137 The energy resolution of Cs is 6.83%. Similarly, the detector of Example 3 with Ga / PbO / CsPbBr3 single crystal layer / PbO / Pt structure is 662keV 137 The energy resolution of Cs is 7.72%. The detector of Example 4 has a structure of EGaIn / PbO / CsPbBr3 single crystal layer / PbO / Ag for 662keV 137 The Cs energy resolution is 8.19%.

[0072] The detectors with different structures in Examples 2-4 and Comparative Examples 1-3 were used to detect 662keV 137 From the Cs energy resolution test structure, it can be seen that the detector with a double-layer PbO structure has the best resolution, and the resolution of the detector with a single-layer PbO structure is improved compared with that of the detector without a PbO layer structure; the difference between the detector structures in Comparative Example 2 and Comparative Example 3 is the position of the PbO layer. In Comparative Example 2, the PbO layer is located between the first metal electrode layer 1 and the CsPbBr3 single crystal layer 3, and in Comparative Example 3, the PbO layer is located between the second metal electrode layer 5 and the CsPbBr3 single crystal layer 3. From the comparison test results, it can be seen that the presence of a double PbO layer in the detector of the present application improves the detector performance in two aspects. One is to passivate the surface state of the surface and reduce the non-radiative recombination of photogenerated carriers. The other is that the improved surface work function promotes the improvement of the Schottky barrier, and the improvement of the Schottky barrier dominates the improvement of the detector performance.

[0073] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A CsPbBr3 single crystal based gamma ray energy spectrum detector, characterized in that: The structure comprises, from top to bottom, a first metal electrode layer (1), a first PbO layer (2), a CsPbBr3 single crystal layer (3), a second PbO layer (4), and a second metal electrode layer (5).

2. The CsPbBr3 single crystal based gamma-ray energy spectrum detector according to claim 1, characterized in that: The thickness of the first metal electrode layer (1) is 10-100 nm, and its area is smaller than that of the first PbO layer (2). The first metal electrode layer (1) is a low work function metal electrode and can form a Schottky junction with a CsPbBr3 single crystal.

3. The CsPbBr3 single crystal based gamma ray energy spectrum detector according to claim 1, characterized in that: The second metal electrode layer (5) has a thickness of 10-100 nm, an area greater than or equal to that of the first metal electrode layer (1), and forms a counter electrode with the first metal electrode layer (1).

4. The CsPbBr3 single crystal based gamma ray energy spectrum detector according to claim 1, characterized in that: The first metal electrode layer (1) is an indium electrode In, a gallium electrode Ga or a gallium-indium eutectic electrode EGaIn, and the second metal electrode layer (5) is a gold electrode Au, a platinum electrode Pt or a silver electrode Ag.

5. The CsPbBr3 single crystal based gamma ray energy spectrum detector according to claim 1, characterized in that: The thickness of the CsPbBr3 single crystal layer (3) is 1-10 mm.

6. The CsPbBr3 single crystal based gamma ray energy spectrum detector according to claim 1, characterized in that: The thickness of the first PbO layer (2) and the second PbO layer (4) are both 5-100 nm.

7. A method for preparing a CsPbBr3 single crystal based gamma-ray energy spectrum detector according to any one of claims 1 to 6, characterized in that: The steps include: S1, cutting, grinding and polishing a CsPbBr3 single crystal to obtain a CsPbBr3 single crystal layer (3) for absorbing gamma rays; S2, preparing a first PbO layer (2) and a second PbO layer (4) on the upper and lower surfaces of the CsPbBr3 single crystal layer (3), respectively; S3, using a vacuum evaporation method or a coating method to prepare a first metal electrode layer (1) on the surface of the first PbO layer (2), and to prepare a second metal electrode layer (5) on the surface of the second PbO layer (4); S4. Use conductive silver paste and wires to connect the first metal electrode layer (1) and the second metal electrode layer (5) in the structure of step S3 to the electrodes of the PCB board respectively, so as to prepare a CsPbBr3 single crystal based gamma-ray energy spectrum detector.

8. The method for preparing the CsPbBr3 single crystal based gamma-ray energy spectrum detector according to claim 6, characterized in that: The CsPbBr3 single crystal described in step S1 is prepared by a solution method or a melt method; the preparation method of the first PbO layer (2) and the second PbO layer (4) in step S2 is one of high pulse energy density ultraviolet laser surface irradiation, oxygen plasma treatment, and chemical vapor deposition.

9. The method for preparing a CsPbBr3 single crystal based gamma-ray energy spectrum detector according to claim 8, characterized in that: Step S1 The preparation method of the first PbO layer (2) and the second PbO layer (4) is as follows: by using a KrF excimer laser, the energy density of the laser is set to 20-60 mJ / cm 2 The laser operating frequency is set to 1-100 Hz, the number of pulses is 20-200, and the upper and lower surfaces of the CsPbBr3 single crystal layer (3) are irradiated respectively, thereby sequentially generating a first PbO layer (2) and a second PbO layer (4).

10. The method for preparing the CsPbBr3 single crystal based gamma-ray energy spectrum detector according to claim 7, characterized in that: In step S3, the vacuum evaporation method is used to prepare the first metal electrode layer (1) and the second metal electrode layer (5) during the deposition process. The pressure in the deposition chamber is not higher than 1×10 -4 Pa under vacuum conditions, the evaporation rate is The deposition time was 1–50 minutes.

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