Semiconductor single crystal film, preparation method thereof and photoelectric detector

Abstract

The invention discloses a semiconductor single crystal film, a preparation method thereof and a photoelectric detector, and relates to the technical field of photoelectric detectors. The semiconductor single crystal thin film comprises a substrate, a PbS buffer layer and a semiconductor single crystal layer. The PbS buffer layer is formed by taking a PbS single crystal block layer grown on the surface of the substrate as a raw material and continuously growing on the surface of the substrate. The method has the beneficial effects that the PbS is used as the buffer layer to grow the semiconductor film with high quality and excellent single crystal property in a lattice matching manner, and meanwhile, the continuous growth of the PbS buffer layer and the semiconductor single crystal layer is realized by utilizing the temperature gradient generated by non-uniform heating of the tubular furnace in the chemical vapor deposition process, so that the temperature rise time is effectively shortened, the cost is reduced, and the production efficiency is improved. Meanwhile, interface pollution and defect introduction caused by multiple times of transfer are avoided, and the quality and performance of the thin film are remarkably improved. The photoelectric detector prepared based on the technology has higher sensitivity and can be widely applied to the fields of infrared detection and the like.

Description

Technical Field

[0001] The invention relates to the field of photoelectric detectors, and in particular to a semiconductor single crystal film and a preparation method thereof, and a photoelectric detector. Background Art

[0002] With the continuous advancement of science and technology, semiconductor single crystal thin films are increasingly used in optoelectronic devices, such as photodetectors, solar cells, light-emitting diodes, etc. However, traditional semiconductor single crystal thin film growth technology faces many challenges when facing non-layered materials or materials with large lattice mismatch with the substrate. For example, direct growth often leads to a large number of defects in the film, affecting its performance and application effects, while the use of buffer layer lattice matching can effectively avoid the above situation.

[0003] Although the existing buffer layer technology can improve the quality of the film, it has limitations. Some buffer layer materials have a low lattice match with the semiconductor film, resulting in many defects during epitaxial growth. At the same time, the traditional buffer layer preparation process is complex and costly, and is not compatible with mainstream semiconductor processes, which limits its application scope.

[0004] Therefore, finding a buffer layer technology with simple process and low cost has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a semiconductor single crystal thin film and a preparation method thereof and a photodetector, specifically a PbS buffer layer assisted semiconductor single crystal thin film growth method and a photodetector.

[0006] The technical solution of the present invention is as follows: A first aspect of the present invention provides a semiconductor single crystal thin film, comprising a substrate, a PbS buffer layer grown on the substrate, and a semiconductor single crystal layer grown on the PbS buffer layer; The PbS buffer layer is formed by continuous growth on the surface of the substrate using a PbS single crystal bulk layer as a raw material.

[0007] Optionally, the thickness of the PbS single crystal block layer is 1 micron-10 microns, preferably 2 microns-5 microns, to ensure that it can be fully epitaxially grown on the substrate without any residue, thereby reducing contamination for the subsequent growth of semiconductor single crystal thin films.

[0008] Optionally, the thickness of the PbS buffer layer is 5 nanometers to 50 nanometers.

[0009] Optionally, the PbS single crystal block layer is a PbS single crystal block layer grown on a substrate, and specifically, the PbS single crystal block layer can be grown on the surface of the substrate by physical vapor deposition or chemical vapor deposition to obtain a PbS single crystal block layer grown on the substrate; the substrate is at least one of strontium titanate, silicon and silicon dioxide, and the crystal orientation of strontium titanate is (100).

[0010] Optionally, the semiconductor single crystal layer and the PbS buffer layer are prepared in the same method, and by controlling the heating temperature, PbS single crystals are first continuously grown on the surface of the substrate to form the PbS buffer layer, and then semiconductor single crystals are continuously grown on the PbS buffer layer to form the semiconductor single crystal layer.

[0011] Specifically, the method for preparing a PbS buffer layer on a substrate and the method for growing a semiconductor single crystal thin film on the PbS buffer layer are chemical vapor deposition (CVD), and in the same CVD process, the continuous growth of the PbS buffer layer and the semiconductor single crystal layer is achieved by controlling the temperature gradient generated by uneven heating in a tube furnace.

[0012] Optionally, the material of the semiconductor single crystal layer is a semiconductor material with a face-centered cubic crystal structure, such as SeSn, PbTe, etc.

[0013] Optionally, the semiconductor single crystal layer is at least one of a SeSn single crystal layer and a PbSnTe single crystal layer, and the thickness of the semiconductor single crystal layer is 0.5 microns to 1 microns. Preferably, the thickness of the PbSnTe single crystal layer is 0.7μm - 1μm, which can be adjusted according to specific application requirements to achieve effective detection of infrared light in different bands.

[0014] Optionally, the substrate is strontium titanate, and the crystal orientation is (100).

[0015] A second aspect of the present invention provides a method for preparing a semiconductor single crystal thin film, comprising the following steps: S1. Growing a PbS single crystal block layer on the surface of a substrate by physical vapor deposition or chemical vapor deposition to obtain a substrate having a PbS single crystal block layer grown thereon; S2. Place the raw material for preparing the semiconductor single crystal layer, the substrate with the PbS single crystal block layer grown thereon, and the substrate in the chemical vapor deposition equipment in sequence along the flow direction of the carrier gas, control the heating temperature, and transport the vapor formed by the PbS single crystal block layer to the surface of the substrate by the carrier gas to form a PbS buffer layer, and then transport the vapor formed by the raw material for preparing the semiconductor single crystal layer to the surface of the PbS buffer layer by the carrier gas to form a semiconductor single crystal layer.

[0016] Optionally, the specific steps of S1 include: Place PbS powder, S powder and substrate in the device and evacuate the device to 5×10 -4 Pa-2×10 -3 Pa, then heating up, then keeping the temperature, and finally cooling down, the steam formed by the PbS powder and the S powder evaporates onto the substrate, forming a PbS single crystal block layer on the surface of the substrate; The heating temperature of the PbS powder is 500°C-700°C, the heating rate is ≤10°C / min, and the time from room temperature to the heating temperature of the PbS powder is 50min-60min; The heating temperature of the S powder is 200°C-300°C, and the heating rate is ≤5°C / min; The heating temperature of the substrate is 200°C-300°C; The insulation time is 5 min-7 min.

[0017] Optionally, the specific steps of S2 include: Along the flow direction of the carrier gas, the raw material for preparing the semiconductor single crystal layer, the substrate with the PbS single crystal block layer grown thereon, and the substrate are placed in sequence from the center to the tail of the chemical vapor deposition equipment, evacuated, then heated up, then kept warm, and finally cooled down. The vapor formed by the PbS single crystal block layer continuously grows on the surface of the substrate to form a PbS buffer layer, and the vapor formed by the raw material for preparing the semiconductor single crystal layer continuously grows on the surface of the PbS buffer layer to form a semiconductor single crystal layer.

[0018] Optionally, in S2, The raw material for preparing the semiconductor single crystal layer is a mixture of SnTe powder and Pb powder in a mass ratio of 4-6:5-7, or a mixture of SnSe powder and Se powder in a mass ratio of 1-2:2-4; The heating temperature of the raw material for preparing the semiconductor single crystal layer is 700°C-800°C, the heating rate is ≤10°C / min, and the time from room temperature to the heating temperature is 70min-80min; The heating temperature of the substrate on which the PbS single crystal block layer is grown is 500° C.-600° C., and the heating rate is ≤10° C. / min; The heating temperature of the substrate is 200°C-300°C; The insulation time is 3min-15min; The vacuum is evacuated to a vacuum degree of 2Pa-4Pa, and the carrier gas flow rate is controlled to be 100sccm-250sccm.

[0019] A third aspect of the present invention provides a photodetector, comprising the semiconductor single crystal thin film described above or the semiconductor single crystal thin film obtained by the above preparation method.

[0020] The present invention has at least one of the following beneficial effects: 1. The present invention utilizes PbS as a buffer layer grown on a substrate, and then grows a semiconductor single crystal layer on the buffer layer, which helps to obtain a high-quality semiconductor film with excellent single crystal properties, thereby solving the problem of lattice mismatch and other problems in the prior art in which semiconductor films are grown directly on substrates, resulting in a large number of defects in the film. In addition, the present invention first grows a PbS single crystal block layer on a substrate, and then uses the PbS single crystal block layer grown on the surface of the substrate as a raw material, and uses a chemical vapor deposition method to continuously grow the raw material on the surface of the substrate to form the PbS buffer layer, and then grows a semiconductor single crystal layer on the PbS buffer layer. Compared with growing a semiconductor single crystal layer directly on a PbS single crystal block layer, the method of the present invention can reduce the thickness of the PbS buffer layer and the thickness of the semiconductor single crystal layer, making it easier to control their thickness for the next step of processing, thereby improving the quality and performance of the film.

[0021] 2. The present invention utilizes the temperature gradient generated by the uneven heating of the tube furnace during the chemical vapor deposition process to achieve the continuous growth of the PbS buffer layer and the semiconductor single crystal layer in the same preparation method, which not only effectively reduces the heating time, reduces the cost, and controls the thickness of the buffer layer, but also avoids the interface contamination and defect introduction caused by multiple transfers, significantly improving the quality and performance of the film. The photodetector prepared based on this technology has higher sensitivity and response speed, and can be widely used in infrared detection and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the process of the PbS buffer layer-assisted semiconductor single crystal thin film growth method in Examples 1 and 2 of the present invention; Figure 2 Schematic diagram of a method for realizing continuous growth of a PbS buffer layer and a semiconductor single crystal thin film by using a temperature gradient in Examples 1 and 2 of the present invention; Figure 3 The scanning electron microscope surface morphology images of PbSnTe grown with a PbS buffer layer in Example 1 of the present invention and PbSnTe grown without a PbS buffer layer in Comparative Example 1; wherein a is a scanning electron microscope surface morphology image of PbSnTe grown with a PbS buffer layer in Example 1, and b is a scanning electron microscope surface morphology image of PbSnTe grown without a PbS buffer layer in Comparative Example 1; Figure 4 The scanning electron microscope side morphology image of the PbSnTe film obtained by continuously growing the PbS buffer layer and PbSnTe in Example 1 of the present invention and the scanning electron microscope side morphology image of the PbSnTe film directly grown on the surface of the PbS single crystal bulk layer in Comparative Example 2; wherein a corresponds to Example 1, and b corresponds to Comparative Example 2; Figure 5 The X-ray diffraction pattern of the PbSnTe film obtained by continuously growing the PbS buffer layer and PbSnTe in Example 1 of the present invention and the X-ray diffraction pattern of the PbSnTe film grown by using the PbS single crystal bulk layer in Comparative Example 2; wherein a corresponds to Comparative Example 2, and b corresponds to Example 1; Figure 6 The results of the energy spectrometer test of the PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention.

[0023] Figure 7 This is a light microscopic image of a PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention; Figure 8 The long-wave infrared detection performance of PbSnTe grown with a PbS buffer layer in Example 1 of the present invention is characterized. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Example 1 This embodiment provides a method for growing a PbSnTe single crystal thin film with the assistance of a PbS buffer layer, which specifically comprises the following steps: Schematic diagram of the chemical vapor growth process of PbS buffer layer assisted PbSnTe single crystal thin film growth Figure 1 As shown in FIG. 1 , a schematic diagram of a method for realizing continuous growth of a PbS buffer layer and a semiconductor single crystal thin film using a temperature gradient is shown in FIG. Figure 2 As shown, the specific steps include: (1) Growth of PbS single crystal bulk layer.

[0026] 0.2g of PbS (99.99%) powder was placed on the heat source as an evaporation source material, and 0.4g of sulfur powder was placed on another heat source as a supplementary source. Both PbS and sulfur powder were located at the bottom of the high-temperature furnace. The purchased strontium titanate substrate with a crystal orientation of (100) plane was placed on the top of the high-temperature furnace. After the high-temperature furnace was sealed, a mechanical pump and a molecular pump were used to pump 5×10 -4 Pa.

[0027] The heating temperature of the sulfur powder supplement source is 300°C, the heating temperature of the PbS powder is set to 500°C, the heating rate is 10°C / min, and the heating temperature of the strontium titanate substrate is set to 250°C, and the heating rate is 5°C / min; the time for the high-temperature furnace to heat up from room temperature to the heating temperature of the PbS powder (500°C) is 60 minutes, and the steam formed by the PbS powder and the sulfur powder supplement source evaporates to the surface of the strontium titanate substrate and reacts for 6 minutes, then the heating power of the high-temperature furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a 2-micron thick PbS single crystal block layer grown on the surface of the strontium titanate substrate.

[0028] (2) Continuous growth of PbS buffer layer and PbSnTe single crystal layer.

[0029] like Figure 2 As shown, on the basis of the strontium titanate substrate on which the PbS single crystal block layer has been grown, along the flow direction of the carrier gas (argon gas) from upstream to downstream, 0.2g of SnTe (99.999%) and 0.2g of Pb (99.999%) are mixed as evaporation source materials and placed in the center of a horizontal tube furnace with a diameter of 2 inches; the strontium titanate substrate on which the PbS single crystal block layer has been grown is set at the end of the furnace 10cm away from the outlet, and the substrate strontium titanate is set at the end of the furnace 3cm away from the outlet; after the tube furnace is sealed, a mechanical pump is used to evacuate the vacuum to a vacuum degree of 2Pa, and the carrier gas flow rate is controlled to be 100sccm. The heating temperature of the evaporation source material is set to 780°C, and the heating rate is 10°C / min. The heating temperature of the PbS single crystal block layer along the temperature gradient is 550°C, and the heating rate is 10°C / min. The heating temperature of the substrate strontium titanate is set to 250°C, and the heating rate is 10°C / min. The time for the tubular furnace to heat up from room temperature to the heating temperature (780°C) of the evaporation source material is 78 minutes. The steam first formed by heating the PbS single crystal block layer grown on the strontium titanate substrate is transported by a carrier gas to the surface of the substrate strontium titanate for reaction for 30 seconds, and a PbS buffer layer is continuously grown on the surface of the substrate strontium titanate. The steam formed by the evaporation source after heating is then transported by a carrier gas to the surface of the substrate strontium titanate with the PbS buffer layer formed thereon for reaction for 5 minutes, and a PbSnTe single crystal layer is continuously grown on the PbS buffer layer. The heating power of the tubular furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a PbSnTe single crystal film.

[0030] Comparative Example 1 The only difference from Example 1 is that step (1) is not performed, and in step (2), there is no need to add a strontium titanate substrate on which a PbS single crystal bulk layer is grown, and a PbSnTe single crystal thin film is grown directly on the surface of the strontium titanate substrate. The other steps are the same as in Example 1.

[0031] Comparative Example 2 The only difference from Example 1 is that in step (2), no substrate strontium titanate needs to be added, and the PbSnTe single crystal layer is directly grown on the surface of the strontium titanate substrate on which the PbS single crystal bulk layer has been grown in step (1).

[0032] The performance of the PbSnTe thin film grown with a PbS buffer layer prepared in Example 1 and the PbSnTe thin films prepared in Comparative Example 1 and Comparative Example 2 was tested, and the test results are as follows: Figure 3 The SEM surface morphology of the PbSnTe film grown with a PbS buffer layer in Example 1 of the present invention and the PbSnTe film grown without a PbS buffer layer in Comparative Example 1 is shown in the figure. It can be seen from the figure that the PbSnTe film grown with a PbS buffer layer prepared in Example 1 ( Figure 3 a) The surface density is significantly better than that of the comparative example 1 in which the PbSnTe film is grown without a PbS buffer layer ( Figure 3 b), which shows that by first forming a PbS buffer layer on the substrate and then growing a semiconductor single crystal (PbSnTe) thin film on the PbS buffer layer, it helps to make the growth orientation of PbSnTe consistent while ensuring that the single crystal film can meet a requirement for light detection.

[0033] Figure 4 The SEM side morphology of the PbSnTe film obtained by continuously growing the PbS buffer layer and PbSnTe in Example 1 of the present invention and the SEM side morphology of the PbSnTe film directly grown on the surface of the PbS single crystal block layer in Comparative Example 2. From the data in the figure, it can be seen that the thickness of the PbSnTe film obtained by continuously growing the PbS buffer layer and PbSnTe is only 0.71μm ( Figure 4 a), while the total thickness of the PbSnTe film grown directly on the surface of the PbS single crystal bulk layer is about 2.3-6μm ( Figure 4 b), which shows that obtaining the PbSnTe film by continuously growing the PbS buffer layer and PbSnTe helps to reduce the surface thickness of the PbSnTe and the thickness of the PbS buffer layer, making it easier to control their thickness for the next step of processing.

[0034] Figure 5 The X-ray diffraction pattern of the PbSnTe film obtained by continuously growing the PbS buffer layer and PbSnTe in Example 1 of the present invention ( Figure 5 b) and the X-ray diffraction pattern of the PbSnTe film grown directly on the surface of the PbS single crystal bulk layer in Comparative Example 2 ( Figure 5a in the figure); it can be seen from the figure that both growth methods can obtain PbSnTe films with good single crystal performance, but the PbSnTe film grown directly on the surface of the PbS single crystal block layer can clearly see the characteristic peak position of the PbS crystal, which further explains its thickness.

[0035] Figure 6 The results of the energy spectrometer test of the PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention are shown in the figure. From the data in the figure, it can be seen that the elements are evenly distributed.

[0036] Figure 7 This is an optical microscopic image of a PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention; combined with the scanning electron microscopic image, it can be seen that the film has a uniform texture and has the luster of a semiconductor film.

[0037] Figure 8 The long-wave infrared detection performance of the PbSnTe device grown with a PbS buffer layer in Example 1 of the present invention is characterized. From the characterization results, it can be seen that the PbSnTe device grown with a PbS buffer layer can still achieve a photoelectric response of the microvolt level under the conditions of a light power of the microwatt level, demonstrating its reliability in the field of infrared photoelectric detection.

[0038] Example 2 This embodiment provides a method for PbS buffer layer-assisted SnSe single crystal thin film growth, which specifically comprises the following steps: Schematic diagram of chemical vapor growth process of PbS buffer layer assisted SnSe single crystal thin film growth Figure 1 As shown, including: (1) Growth of PbS single crystal bulk layer.

[0039] 0.2 g of PbS (99.99%) powder was placed on the heat source as an evaporation source material, and 0.4 g of sulfur powder was placed on another heat source as a supplementary source, both of which were located at the bottom of the high-temperature furnace. The purchased strontium titanate substrate with a crystal orientation of (100) plane was placed on the top of the high-temperature furnace. After the high-temperature furnace was sealed, a mechanical pump and a molecular pump were used to pump 5×10 -4 Pa.

[0040] The heating temperature of the sulfur powder supplement source is 300°C, the heating temperature of the PbS powder is set to 500°C, the heating rate is 10°C / min, and the heating temperature of the strontium titanate substrate is set to 250°C, and the heating rate is 5°C / min; the time for the high-temperature furnace to heat up from room temperature to the heating temperature of the PbS powder (500°C) is 60 minutes, and the steam formed by the PbS powder and the sulfur powder supplement source evaporates to the surface of the strontium titanate substrate and reacts for 6 minutes, then the heating power of the high-temperature furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a 2-micron thick PbS single crystal block layer grown on the surface of the strontium titanate substrate.

[0041] (2) Continuous growth of PbS buffer layer and SnSe single crystal layer.

[0042] like Figure 2 As shown, on the basis of the strontium titanate substrate on which the PbS single crystal block layer has been grown, along the flow direction of the carrier gas from upstream to downstream, 0.1g of SnSe (99.999%) and 0.2g of Se (99.999%) are mixed as evaporation source materials and placed in the center of a horizontal tube furnace with a diameter of 2 inches; the PbS single crystal block layer is set at the end of the furnace 10cm away from the outlet, and the substrate strontium titanate is set at the end of the furnace 3cm away from the outlet. After the tube furnace is sealed, a mechanical pump is used to evacuate the vacuum to 2Pa, and the carrier gas flow rate is controlled to be 100sccm. The heating temperature of the evaporation source material was set to 700°C, and the heating rate was 10°C / min. The temperature of the PbS single crystal block layer along the temperature gradient was 550°C, and the heating rate was 10°C / min. The substrate strontium titanate temperature was set to 250°C, and the heating rate was 10°C / min. The time for the tubular furnace to heat up from room temperature to the heating temperature (700°C) of the evaporation source material was 70 minutes. The vapor formed by the PbS single crystal block layer was first transported to the surface of the strontium titanate substrate by a carrier gas to react for 1 minute. Then, the vapor formed by the reaction source was transported to the surface of the strontium titanate substrate by a carrier gas to react for 5 minutes. Then, the heating power of the tubular furnace was cut off, and the furnace body was naturally cooled to room temperature to obtain a SnSe single crystal thin film.

[0043] Comparative Example 3 The only difference from Example 2 is that step (1) is not performed, and in step (2), there is no need to add a strontium titanate substrate on which a PbS single crystal bulk layer is grown, and a SnSe single crystal thin film is grown directly on the surface of the strontium titanate substrate. The other steps are the same as in Example 1.

[0044] Comparative Example 4 The only difference from Example 2 is that in step (2), no substrate strontium titanate needs to be added, and the SnSe single crystal thin film is directly grown on the surface of the strontium titanate substrate on which the PbS single crystal bulk layer is grown in step (1).

[0045] Performance tests were performed on the SnSe single crystal thin film grown with a PbS buffer layer prepared in Example 2 and the SnSe single crystal thin films prepared in Comparative Examples 3 and 4, and the test results were similar to those in Example 1, Comparative Examples 2 and 3, that is, the surface density of the SnTe thin film grown with a PbS buffer layer prepared in Example 2 was significantly better than that of the SnTe thin film grown without a PbS buffer layer prepared in Comparative Example 3. This shows that by first forming a PbS buffer layer on a substrate and then growing a semiconductor single crystal (SnTe) thin film on the PbS buffer layer, it is helpful to make the SnTe growth orientation consistent while ensuring that a requirement of the single crystal thin film for light detection can be met.

[0046] Similarly, Example 2 obtains a SnTe film by continuously growing a PbS buffer layer and SnTe. The thickness of the SnTe film obtained is thinner than that of the comparative example 4, indicating that the method of the present invention helps to reduce the surface thickness of SnTe and the thickness of the PbS buffer layer, making it easier to control the thickness for the next step of processing.

[0047] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A semiconductor single crystal thin film, characterized in that: It includes a substrate, a PbS buffer layer grown on the substrate, and a semiconductor single crystal layer grown on the PbS buffer layer; The PbS buffer layer is formed by continuous growth on the surface of the substrate using a PbS single crystal bulk layer as a raw material.

2. The semiconductor single crystal thin film according to claim 1, characterized in that: The thickness of the PbS single crystal block layer is 1 micrometer to 10 micrometers, and the thickness of the PbS buffer layer is 5 nanometers to 50 nanometers.

3. The semiconductor single crystal thin film according to claim 1, characterized in that: The PbS single crystal bulk layer is a PbS single crystal bulk layer grown on a substrate; The semiconductor single crystal layer and the PbS buffer layer are prepared in the same method. By controlling the heating temperature, PbS single crystals are firstly continuously grown on the surface of the substrate to form the PbS buffer layer, and then semiconductor single crystals are continuously grown on the PbS buffer layer to form the semiconductor single crystal layer.

4. The semiconductor single crystal thin film according to claim 1, characterized in that: The material of the semiconductor single crystal layer is a semiconductor material with a face-centered cubic crystal structure; the thickness of the semiconductor single crystal layer is 0.5 micrometer to 1 micrometer.

5. The semiconductor single crystal thin film according to claim 1, characterized in that: The semiconductor single crystal layer is at least one of a SeSn single crystal layer and a PbSnTe single crystal layer; and the substrate is strontium titanate.

6. A method for preparing a semiconductor single crystal thin film according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Growing a PbS single crystal block layer on the surface of a substrate by physical vapor deposition or chemical vapor deposition to obtain a substrate having a PbS single crystal block layer grown thereon; S2. Place the raw material for preparing the semiconductor single crystal layer, the substrate with the PbS single crystal block layer grown thereon, and the substrate in the chemical vapor deposition equipment in sequence along the flow direction of the carrier gas, control the heating temperature, and transport the vapor formed by the PbS single crystal block layer to the surface of the substrate by the carrier gas to form a PbS buffer layer, and then transport the vapor formed by the raw material for preparing the semiconductor single crystal layer to the surface of the PbS buffer layer by the carrier gas to form a semiconductor single crystal layer.

7. The preparation method according to claim 6, characterized in that: The specific steps of S1 include: Place PbS powder, S powder and substrate in the device and evacuate the device to 5×10 -4 Pa-2×10 -3 Pa, then heating up, then keeping the temperature, and finally cooling down, the steam formed by the PbS powder and the S powder evaporates onto the substrate, forming a PbS single crystal block layer on the surface of the substrate; The heating temperature of the PbS powder is 500°C-700°C, the heating rate is ≤10°C / min, and the time from room temperature to the heating temperature of the PbS powder is 50min-60min; The heating temperature of the S powder is 200°C-300°C, and the heating rate is ≤5°C / min; The heating temperature of the substrate is 200°C-300°C; The insulation time is 5 min-7 min.

8. The preparation method according to claim 6, characterized in that: The specific steps of S2 include: Along the flow direction of the carrier gas, the raw material for preparing the semiconductor single crystal layer, the substrate with the PbS single crystal block layer grown thereon, and the substrate are placed in sequence from the center to the tail of the chemical vapor deposition equipment, evacuated, then heated up, then kept warm, and finally cooled down. The vapor formed by the PbS single crystal block layer continuously grows on the surface of the substrate to form a PbS buffer layer, and the vapor formed by the raw material for preparing the semiconductor single crystal layer continuously grows on the surface of the PbS buffer layer to form a semiconductor single crystal layer.

9. The preparation method according to claim 8, characterized in that: In S2, The raw material for preparing the semiconductor single crystal layer is a mixture of SnTe powder and Pb powder in a mass ratio of 4-6:5-7, or a mixture of SnSe powder and Se powder in a mass ratio of 1-2:2-4; The heating temperature of the raw material for preparing the semiconductor single crystal layer is 700°C-800°C, the heating rate is ≤10°C / min, and the time from room temperature to the heating temperature is 70min-80min; The heating temperature of the substrate on which the PbS single crystal block layer is grown is 500° C.-600° C., and the heating rate is ≤10° C. / min; The heating temperature of the substrate is 200°C-300°C; The insulation time is 3min-15min; The vacuum is evacuated to a vacuum degree of 2Pa-4Pa, and the carrier gas flow rate is controlled to be 100sccm-250sccm.

10. A photoelectric detector, characterized in that: Comprising the semiconductor single crystal thin film as described in any one of claims 1 to 5.

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