Perovskite crystal gamma-ray photon counter structure and method of making same

Abstract

The application discloses a perovskite crystal gamma ray photon counter structure and a preparation method thereof. The perovskite crystal gamma ray photon counter structure comprises a perovskite crystal with a band gap gradient distribution and without doping, a p-type perovskite layer and an n-type perovskite layer. The perovskite crystal has opposite first and second surfaces, the p-type perovskite layer is arranged on the first surface, and the n-type perovskite layer is arranged on the second surface. The energy band gap of the perovskite crystal gradually increases or decreases from the first surface to the second surface. The perovskite crystal with a band gap gradient distribution and without doping between the p-type perovskite layer and the n-type perovskite layer improves the lattice matching rate between the crystal layers, effectively inhibits ion migration of the perovskite, and reduces the baseline drift and noise of a detection signal.

Description

Technical Field

[0001] This invention relates to the field of radiation detection technology, and in particular to a perovskite crystal gamma-ray photon counter structure and its preparation method. Background Technology

[0002] Gamma rays are composed of high-energy photons (tens of kiloelectron volts to hundreds of megaelectron volts), exhibiting both wave and particle properties. Due to their high photon energy, gamma rays possess strong penetrating power, making them crucial for applications in medical diagnosis and treatment, nuclear radiation technology, space exploration, materials science, industrial non-destructive testing, and biotechnology. These applications require knowledge of the intensity and energy distribution of gamma rays as they pass through the object being detected; therefore, gamma ray intensity and energy detection is of paramount importance.

[0003] Gamma-ray detection can generally be divided into two forms: direct detection and indirect detection. Of these two methods, direct detection offers higher quantum efficiency and resolution, and is more widely used. Photon counting is the mainstream technique for obtaining gamma-ray intensity and energy spectrum distribution, and is used for direct detection. In recent years, the use of lead halide perovskite crystals for X-ray and gamma-ray detection has been proposed, as they are inexpensive and can operate at room temperature. Using perovskite crystals for gamma-ray photon counting could potentially yield very high counting performance.

[0004] Currently, most commercially available gamma-ray photon counters use HPGe, CZT, CdTe, or other inorganic semiconductor materials as the sensing active material. These gamma-ray photon counters are limited by cost and fabrication processes, making it difficult to achieve large-scale array detection. Perovskite crystals have a simple fabrication process and are easy to obtain large-size single crystals, making them promising candidates for gamma-ray photon counters and energy dispersive spectrometers. However, perovskite crystals are typical ionic crystals, and under an electric field, ion migration occurs, causing baseline drift and additional noise in the detection signal, ultimately affecting the resolution of the perovskite gamma-ray photon counter. Therefore, suppressing ion migration in perovskite gamma-ray photon counters is a key problem that needs to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a perovskite crystal gamma-ray photon counter structure and its preparation method that can suppress the migration of ions in perovskite crystals.

[0006] The technical solution adopted by the present invention to solve its technical problem is: to provide a perovskite crystal γ-ray photon counter structure, including a perovskite crystal with a bandgap gradient distribution and no doping, a p-type perovskite layer and an n-type perovskite layer;

[0007] The perovskite crystal has a first surface and a second surface opposite to each other. The p-type perovskite layer is disposed on the first surface, and the n-type perovskite layer is disposed on the second surface. The energy band gap of the perovskite crystal gradually increases or gradually decreases from the first surface to the second surface.

[0008] Preferably, the p-type perovskite layer is metal ion-doped MAPbBr3; the n-type perovskite layer is metal ion-doped MAPbCl3;

[0009] The metal ion doped in the p-type perovskite layer is Ag. + Cs + Li + or In 3+ The metal ions doped in the n-type perovskite layer are Bi. 3+ Cu 2+ Sb 3+ or Mg 2+ .

[0010] Preferably, the perovskite crystal comprises an undoped MAPbBr3 layer and an undoped MAPbBr3 layer sequentially disposed between the p-type perovskite layer and the n-type perovskite layer. 2.5 Cl 0.5 The layer includes a layer of undoped MAPbCl3.

[0011] Preferably, the perovskite crystal comprises undoped MAPbBr2 strands sequentially between the p-type perovskite layer and the n-type perovskite layer. 2.5 Cl 0.5 Layer, undoped MAPbBr2Cl layer and undoped MAPbBr 1.5 Cl 1.5 layer.

[0012] Preferably, in the perovskite crystal γ-ray photon counter structure, the perovskite crystal serves as an undoped intrinsic layer, forming a pin junction with the p-type perovskite layer and the n-type perovskite layer;

[0013] During gamma-ray detection, a positive bias voltage is applied to the n-type perovskite layer, the p-type perovskite layer is grounded, and a reverse bias voltage is applied to the pin junction. The p / i and n / i layers form a depletion layer, and the electric field of the depletion layer is used to suppress dark-state current injection. Because the perovskite crystal has a bandgap gradient distribution, ion junctions are formed between the layers. The built-in electric field of the ion junctions weakens the ion migration of the perovskite, thereby reducing the baseline drift and noise of the detection signal.

[0014] This invention also provides a method for preparing a perovskite crystal gamma-ray photon counter structure, comprising the following steps:

[0015] S1. The first undoped crystal layer is grown using the reverse temperature method;

[0016] S2. An undoped second crystal layer is epitaxially grown on the first crystal layer;

[0017] S3. An undoped third crystal layer is epitaxially grown on the second crystal layer;

[0018] S4. Bi ions are doped onto the third crystal layer to form an n-type perovskite layer;

[0019] S5. Ag ions are doped on the side of the first crystal layer facing away from the second crystal layer to form a p-type perovskite layer.

[0020] The first crystal layer, the second crystal layer, and the third crystal layer together form an undoped perovskite crystal, and the energy band gap of the perovskite crystal gradually increases or decreases from the first crystal layer to the third crystal layer.

[0021] Preferably, the p-type perovskite layer is Ag ion-doped MAPbBr3; the n-type perovskite layer is Bi ion-doped MAPbCl3.

[0022] Preferably, the first crystal layer is an undoped MAPbBr3 layer, and the second crystal layer is an undoped MAPbBr3 layer. 2.5 Cl 0.5 The third crystal layer is an undoped MAPbCl3 layer.

[0023] Preferably, the first crystal layer is undoped MAPbBr 2.5 Cl 0.5 The second crystal layer is an undoped MAPbBr2Cl layer, and the third crystal layer is an undoped MAPbBr2Cl layer. 1.5 Cl 1.5 layer.

[0024] Preferably, in the perovskite crystal γ-ray photon counter structure, the perovskite crystal serves as an undoped intrinsic layer, forming a pin junction with the p-type perovskite layer and the n-type perovskite layer;

[0025] During gamma-ray detection, a positive bias voltage is applied to the n-type perovskite layer, the p-type perovskite layer is grounded, and a reverse bias voltage is applied to the pin junction. The p / i and n / i layers form a depletion layer, and the electric field of the depletion layer is used to suppress dark-state current injection. Because the perovskite crystal has a bandgap gradient distribution, ion junctions are formed between the layers (first to third crystal layers). The built-in electric field of the ion junctions weakens the ion migration of the perovskite, thereby reducing the baseline drift and noise of the detection signal.

[0026] The perovskite crystal gamma-ray photon counter structure of the present invention improves the lattice matching rate between the crystal layers by using an undoped perovskite crystal with a bandgap gradient distribution between the p-type and n-type perovskite layers, effectively suppressing ion migration of the perovskite and reducing baseline drift and noise of the detection signal.

[0027] By reducing detection noise, the resolution of the gamma-ray energy spectrum can be improved. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0029] Figure 1 This is a schematic diagram of the structure of a perovskite crystal gamma-ray photon counter according to an embodiment of the present invention;

[0030] Figure 2 This is a SEM image of a MAPbBr3 layer epitaxially grown directly on an n-type MAPbCl3 perovskite crystal;

[0031] Figure 3 Is Figure 2 SEM images with added buffer layers on top of the existing ones (also for) Figure 1 (Corresponding SEM image);

[0032] Figure 4 This is a surface potential curve of a bilayer crystal semiconductor junction;

[0033] Figure 5 This is a surface potential curve of another type of bilayer crystal semiconductor junction;

[0034] Figure 6 It is a surface potential curve of a four-layer crystalline semiconductor junction;

[0035] Figure 7 This is the JV curve of a single-layer crystal layer;

[0036] Figure 8 It is a JV curve diagram of two crystal layers;

[0037] Figure 9 It is a JV curve diagram of three crystal layers;

[0038] Figure 10 This is a JV curve diagram of four crystal layers;

[0039] Figure 11 This is a flowchart illustrating the fabrication process of a perovskite crystal gamma-ray photon counter structure according to an embodiment of the present invention. Detailed Implementation

[0040] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] like Figure 1 As shown, a perovskite crystal gamma-ray photon counter structure according to an embodiment of the present invention includes a p-type perovskite layer 10, an n-type perovskite layer 20, and a perovskite crystal 30; the perovskite crystal 30 has a first surface and a second surface opposite to each other, the p-type perovskite layer 10 is disposed on the first surface of the perovskite crystal 30, and the n-type perovskite layer 20 is disposed on the second surface of the perovskite crystal 30.

[0042] In this structure, both the p-type perovskite layer 10 and the n-type perovskite layer 20 are ion-doped crystal layers; the perovskite crystal 30, as an undoped intrinsic layer (i-type layer), is a γ-ray photon absorber and is located between the p-type perovskite layer 10 and the n-type perovskite layer 20. Together, the three form a pin junction. This semiconductor junction not only facilitates the transport of photogenerated carriers but also effectively suppresses dark-state currents and noise.

[0043] The perovskite crystal 30 is not a single-bandgap crystal, but has a bandgap gradient distribution. The bandgap energy of the perovskite crystal 30 gradually increases or decreases from the first surface to the second surface.

[0044] The p-type perovskite layer 10 is a metal ion-doped MAPbBr3, wherein the doped metal ion can be Ag. + Cs + Li + or In 3+ For example, p-type perovskite layer 10 is Ag ion-doped MAPbBr3. n-type perovskite layer 20 is metal ion-doped MAPbCl3, where the doped metal ion is Bi. 3+ Cu 2+ Sb 3+ or Mg 2+ For example, the n-type perovskite layer 20 is Bi ion-doped MAPbCl3.

[0045] Due to the lattice constant of the n-type MAPbCl3 perovskite crystal (i.e., n-type perovskite layer 20) The lattice constant of p-type MAPbBr3 perovskite crystal (i.e., p-type perovskite layer 10) The phase difference is significant, with a lattice mismatch rate reaching 2.3%. If the two are directly stacked and connected, defects are likely to occur at the interface. (Reference) Figure 2 It shows scanning electron microscope (SEM) images of a MAPbBr3 layer epitaxially grown directly on an n-type MAPbCl3 perovskite crystal. Figure 2As can be seen, a clear interface exists between the two layers, which is caused by interface defects due to lattice mismatch. To solve this problem, this invention inserts a perovskite crystal 30 with a bandgap gradient distribution as a buffer layer between the p-type perovskite layer 10 and the n-type perovskite layer 20, so that the lattice mismatch rate between the p-type perovskite layer 10 and the n-type perovskite layer 20 is less than 3%. The overall SEM images of the p-type perovskite layer 10, the n-type perovskite layer 20, and the perovskite crystal 30 are shown below. Figure 3 As shown, from Figure 3 As can be seen, after adding perovskite crystal 30 as a buffer layer, no obvious interface defects were observed.

[0046] The perovskite crystal 30 has multiple crystal layers (at least two crystal layers) according to the band gap gradient distribution, such as a first crystal layer 31, a second crystal layer 32 and a third crystal layer 33 with successively decreasing energy band gaps.

[0047] In a preferred embodiment, the perovskite crystal 30 includes an undoped MAPbBr3 layer and an undoped MAPbBr3 layer sequentially disposed between a p-type perovskite layer 10 and an n-type perovskite layer 20. 2.5 Cl 0.5 The crystal consists of a first crystal layer and an undoped MAPbCl3 layer. The undoped MAPbBr3 layer, serving as the first crystal layer 31, has the largest band gap. 2.5 Cl 0.5 The first layer and the second layer (32) and the third layer (33) (undoped MAPbCl3) are respectively used as the second crystal layer 32 and the third crystal layer 33, with the energy band gap decreasing sequentially.

[0048] In another preferred embodiment, the perovskite crystal 30 is an undoped MAPbBr crystal located sequentially between a p-type perovskite layer 10 and an n-type perovskite layer 20. 2.5 Cl 0.5 Layer, undoped MAPbBr2Cl layer and undoped MAPbBr 1.5 Cl 1.5 Layer. Among them, undoped MAPbBr 2.5 Cl 0.5 Layer 31, as the first crystal layer, has the largest energy band gap. The undoped MAPbBr2Cl layer and the undoped MAPbBr... 1.5 Cl 1.5 The layers serve as the second crystal layer 32 and the third crystal layer 33, respectively, with the energy band gap decreasing sequentially.

[0049] In this invention, due to the presence of a series of semiconductor junctions (ion junctions) in the perovskite crystal 30 with a bandgap gradient distribution, the built-in electric field of these semiconductor junctions can effectively suppress ion migration. The analysis of the effect of the perovskite crystal 30 with a bandgap gradient distribution on improving carrier transport capability and suppressing ion migration is as follows:

[0050] The surface potential distribution of perovskite crystal 30 was measured using a Kelvin probe (KFM). An infrared laser was focused onto the tip of a magnetic probe. As the probe scanned across the perovskite crystal surface, the change in surface potential caused minute vibrations in the probe. These minute vibrations were detected by an infrared detector, allowing the calculation of the surface potential change. Figure 4 As shown, the surface potential difference of the bilayer MAPbCl3 / MAPbBr3 crystalline semiconductor junction is 0.073 eV, the heterojunction width is 15 μm, and the calculated built-in electric field of the junction region is 4.86 V / mm. -1 .like Figure 5 As shown, if the heterojunction is changed to MAPbCl3 / MAPbBr 2.5 Cl 0.5 and MAPbBr 2.5 Cl 0.5 / MAPbBr3, whose semiconductor junction surface potential difference and junction width are 0.074 eV and 24 μm, respectively (e.g., ... Figure 5 (as shown in (a)) and 0.013 eV, 3 μm (as shown in (a)) Figure 5 As shown in (b), the calculated electric field strength is 3.08 V / mm. -1 and 4.3Vmm -1 .like Figure 6 As shown in (a), (b), and (c), if the number of crystal layers is increased to four, MAPbCl3 / MAPbBr 1.5 Cl 1.5 MAPbCl3 / MAPbBr 2.5 Cl 0.5 and MAPbBr 2.5 Cl 0.5 The surface potential differences of the MAPbCl3 / MAPbBr3 junction regions were 0.017 eV, 0.024 eV, and 0.013 eV, respectively, and the junction widths were 7 μm, 18 μm, and 3 μm. The calculated MAPbCl3 / MAPbBr ... 1.5 Cl 1.5 The built-in electric field of the junction is 2.4V / mm. -1 MAPbCl3 / MAPbBr 2.5 Cl 0.5 The built-in electric field of the junction is 1.3Vmm. -1 The surface potential difference and junction width of a conventional MAPbCl3 homogeneous pn junction are 0.84 eV and 0.84 μm, respectively. This means that the semiconductor junction formed by perovskite crystals with a bandgap gradient distribution has a wider depletion layer, which is more conducive to the detection of high-energy photons.

[0051] The JV hysteresis curve of perovskite crystals is generally used to characterize the effect of ion migration: due to the polarity of ions, if there is strong ion migration in the semiconductor, the JV curves will show significant differences when scanning the semiconductor with positive and negative bias voltages, i.e., the hysteresis curve of the JV curve will be large. Conversely, if the ion migration is small, the hysteresis curve of the JV curve will be small. (The last sentence appears to be an incomplete thought and is left untranslated.) 2.5 Cl 0.5 The hysteresis properties of the crystal's JV curve are as follows Figure 7 As shown, two-layer perovskite crystals (MAPbCl3 / MAPbBr3) and three-layer perovskite crystals (MAPbCl3 / MAPbBr3) are also shown. 2.5 Cl 0.5 The hysteresis properties of / MAPbBr3 are as follows: Figure 8 and Figure 9 As shown. In Figure 7 In the middle, the JV curves of the forward and reverse scans show a large difference, that is, the hysteresis line of the JV curve is large. This indicates that the monolayer MAPbBr 2.5 Cl 0.5 Ion migration is more severe in crystals; while Figure 8 and Figure 9 In the middle, the difference between the JV curves of forward scan and reverse scan is significantly greater than that of the middle. Figure 7 The smaller size shown indicates that the ion migration of bilayer and trilayer perovskite crystals is greater than that of other crystals. Figure 7 The single-layer structure is weakened. Figure 9 The three-layer structure is superior to Figure 8 The double layer.

[0052] like Figure 10 As shown, when the epitaxial perovskite crystal increases to four layers (MAPbCl3 / MAPbBr), 1.5 Cl 1.5 / MAPbBr 2.5 Cl 0.5 After / MAPbBr3), the JV curve shows a smaller hysteresis, indicating that at this point, MAPbCl3 / MAPbBr 1.5 Cl 1.5 / MAPbBr 2.5 Cl 0.5 The ion migration of / MAPbBr3 is relatively small because of the MAPbCl3 / MAPbBr 1.5 Cl 1.5 / MAPbBr 2.5 Cl 0.5 The energy band gap gradient distribution of / MAPbBr3 and the ion junctions between the layers prevent the migration of ions in the perovskite.

[0053] In response, this invention achieves the goal of effectively suppressing ion migration by using an appropriate energy level gradient distribution (i.e., band gap gradient distribution).

[0054] In summary, the noise of a gamma-ray photon counter originates from dark current fluctuations injected by the external bias power supply and baseline drift caused by perovskite ion migration. This invention addresses this by placing a p-type perovskite layer 10 at the top and an n-type perovskite layer 20 at the bottom, respectively, utilizing the built-in electric field of the depletion layer to block the injected dark current. A wider ion junction is formed using a perovskite crystal 30 with a bandgap gradient distribution. This ion junction suppresses baseline drift caused by ion migration, further reducing the noise of the photon counter.

[0055] refer to Figure 1 and Figure 11 The method for fabricating a perovskite crystal gamma-ray photon counter structure of the present invention, taking an undoped perovskite crystal 30 with three crystal layers as an example, may include the following steps:

[0056] S1. An undoped first crystal layer 31 is grown using a reverse temperature method.

[0057] S2. An undoped second crystal layer 32 is epitaxially grown on the first crystal layer 31.

[0058] The second crystal layer 32 is located on one side of the first crystal layer 31. The energy band gap of the second crystal layer 32 is smaller than that of the first crystal layer 31.

[0059] S3. An undoped third crystal layer 33 is epitaxially grown on the second crystal layer 32.

[0060] The formed third crystal layer 33 is located on the side of the second crystal layer 32 that faces away from the first crystal layer 31. The energy band gap of the third crystal layer 33 is smaller than that of the second crystal layer 32.

[0061] S4. Bi ions are doped onto the third crystal layer 33 to epitaxially generate an n-type perovskite layer 20.

[0062] The n-type perovskite layer 20 is located on the side of the third crystal layer 33 that faces away from the second crystal layer 32.

[0063] S5. Ag ions are doped on the side of the first crystal layer 31 facing away from the second crystal layer 32 to epitaxially generate a p-type perovskite layer 10.

[0064] The first crystal layer 31, the second crystal layer 32 and the third crystal layer 33 together form an undoped perovskite crystal 30 (i-type layer). The perovskite crystal 30 has a bandgap gradient distribution, and its energy bandgap gradually increases or decreases from the first crystal layer 31 to the third crystal layer 33.

[0065] Preferably, the p-type perovskite layer 10 is Ag ion-doped MAPbBr3; the n-type perovskite layer 20 is Bi ion-doped MAPbCl3.

[0066] Correspondingly, in a selective embodiment, the first crystal layer 31 is an undoped MAPbBr3 layer, and the second crystal layer 32 is an undoped MAPbBr3 layer. 2.5 Cl 0.5 The third crystal layer 33 is an undoped MAPbCl3 layer. The stacked structure formed by these three crystal layers, together with the p-type perovskite layer 10 and the n-type perovskite layer 20, is: doped MAPbBr3 / undoped MAPbBr3 layer / undoped MAPbBr3 layer. 2.5 Cl 0.5 Layer / Undoped MAPbCl3 layer / Doped MAPbCl3.

[0067] In another selective embodiment, the first crystal layer 31 is undoped MAPbBr. 2.5 Cl 0.5 The first crystal layer 32 is an undoped MAPbBr2Cl layer, and the second crystal layer 33 is an undoped MAPbBr2Cl layer. 1.5 Cl 1.5 Layers. The stacked structure formed by the above three crystal layers, together with the p-type perovskite layer 10 and the n-type perovskite layer 20, is: doped MAPbBr3 / undoped MAPbBr3. 2.5 Cl 0.5 Layer / Undoped MAPbBr2Cl layer / Undoped MAPbBr 1.5 Cl 1.5 Layer / doped MAPbCl3.

[0068] Understandably, the specific operations of the epitaxial growth, doping and other processes in the above steps can be implemented with reference to existing technologies, and will not be described in detail here.

[0069] In the perovskite crystal gamma-ray photon counter structure of the present invention, the perovskite crystal 30 serves as an undoped intrinsic layer, forming a pin junction with the p-type perovskite layer 10 and the n-type perovskite layer 20. The perovskite crystal 30 exhibits a bandgap gradient, and ion junctions are formed between the layers. The built-in electric field of the ion junctions weakens the ion migration of the perovskite, thereby suppressing baseline drift of the detection signal caused by ion migration.

[0070] In the application of the perovskite crystal gamma-ray photon counter structure of the present invention, the side containing the p-type perovskite layer 10 serves as the incident end, and the n-type perovskite layer 20 serves as the exit end. During gamma-ray detection, a positive bias voltage is applied to the n-type perovskite layer 20, the p-type perovskite layer 10 is grounded, and a reverse bias voltage is applied to the pin junction. The p / i and n / i junctions form a depletion layer, and the built-in electric field of the depletion layer is used to suppress / block dark-state current injection.

[0071] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A perovskite crystal gamma-ray photon counter structure, characterized in that, This includes undoped perovskite crystals with a bandgap gradient distribution, p-type perovskite layers, and n-type perovskite layers. The perovskite crystal has a first surface and a second surface opposite to each other, the p-type perovskite layer is disposed on the first surface, and the n-type perovskite layer is disposed on the second surface; the energy band gap of the perovskite crystal gradually increases or gradually decreases from the first surface to the second surface. The p-type perovskite layer is doped with metal ion MAPbBr3; the n-type perovskite layer is doped with metal ion MAPbCl3; the metal ion doped in the p-type perovskite layer is Ag. + Cs + Li + or In 3+ The metal ions doped in the n-type perovskite layer are Bi. 3+ Cu 2+ Sb 3+ or Mg 2+ ; The perovskite crystal comprises an undoped MAPbBr3 layer and an undoped MAPbBr3 layer sequentially located between the p-type perovskite layer and the n-type perovskite layer. 2.5 Cl 0.5 The perovskite crystal comprises a p-type perovskite layer and an undoped MAPbCl3 layer; or, the perovskite crystal comprises an undoped MAPbBr layer sequentially positioned between the p-type and n-type perovskite layers. 2.5 Cl 0.5 Layer, undoped MAPbBr2Cl layer and undoped MAPbBr 1.5 Cl 1.5 layer.

2. The perovskite crystal gamma-ray photon counter structure according to claim 1, characterized in that, In the perovskite crystal gamma-ray photon counter structure, the perovskite crystal serves as an undoped intrinsic layer, forming a pin junction with the p-type and n-type perovskite layers; During gamma-ray detection, a positive bias voltage is applied to the n-type perovskite layer, the p-type perovskite layer is grounded, and a reverse bias voltage is applied to the pin junction. The p / i and n / i layers form a depletion layer, and the electric field of the depletion layer is used to suppress dark-state current injection. Because the perovskite crystal has a bandgap gradient distribution, ion junctions are formed between the layers. The built-in electric field of the ion junctions weakens the ion migration of the perovskite, thereby reducing the baseline drift and noise of the detection signal.

3. A method for fabricating a perovskite crystal gamma-ray photon counter structure, characterized in that, Includes the following steps: S1. The first undoped crystal layer is grown using the reverse temperature method; S2. An undoped second crystal layer is epitaxially grown on the first crystal layer; S3. An undoped third crystal layer is epitaxially grown on the second crystal layer; S4. Bi ions are doped onto the third crystal layer to form an n-type perovskite layer; S5. Ag ions are doped on the side of the first crystal layer facing away from the second crystal layer to form a p-type perovskite layer. The first crystal layer, the second crystal layer, and the third crystal layer together form an undoped perovskite crystal, and the energy band gap of the perovskite crystal gradually increases or decreases from the first crystal layer to the third crystal layer. The p-type perovskite layer is Ag ion-doped MAPbBr3; the n-type perovskite layer is Bi ion-doped MAPbCl3. The first crystal layer is an undoped MAPbBr3 layer, and the second crystal layer is an undoped MAPbBr3 layer. 2.5 Cl 0.5 The third crystal layer is an undoped MAPbCl3 layer; or, the first crystal layer is an undoped MAPbBr. 2.5 Cl 0.5 The second crystal layer is an undoped MAPbBr2Cl layer, and the third crystal layer is an undoped MAPbBr2Cl layer. 1.5 Cl 1.5 layer.

4. The method for preparing the perovskite crystal γ-ray photon counter structure according to claim 3, characterized in that, In the perovskite crystal gamma-ray photon counter structure, the perovskite crystal serves as an undoped intrinsic layer, forming a pin junction with the p-type and n-type perovskite layers; During gamma-ray detection, a positive bias voltage is applied to the n-type perovskite layer, the p-type perovskite layer is grounded, and a reverse bias voltage is applied to the pin junction. The p / i and n / i layers form a depletion layer, and the electric field of the depletion layer is used to suppress dark-state current injection. Because the perovskite crystal has a bandgap gradient distribution, ion junctions are formed between the layers. The built-in electric field of the ion junctions weakens the ion migration of the perovskite, thereby reducing the baseline drift and noise of the detection signal.

Images