A Semiconductor Single Crystal Thin Film, Its Preparation Method and Photoelectric Detector
By growing the PbS buffer layer on the substrate and growing the semiconductor single crystal layer thereon, the problems of many defects and complex buffer layer technology in traditional semiconductor thin film growth technology are solved, and high-quality and low-cost semiconductor thin film growth is achieved.
Patent Information
- Application Number
- CN202510386793.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-06-20
- Estimated Expiration
- 2045-03-31
AI Technical Summary
When traditional semiconductor single-crystal thin film growth technology faces non-layered materials or materials with large mismatch with the substrate lattice, it has a large number of defects, affecting its performance and application effect. The existing buffer layer technology is complex, high cost and insufficient compatibility with mainstream semiconductor processes.
The PbS buffer layer assists the thin film growth method of semiconductor single crystals. By continuously growing the PbS buffer layer on the substrate and growing the semiconductor single crystal layer thereon, the continuous growth is achieved by using chemical vapor deposition method and temperature gradient control to reduce the thickness and interface contamination of the film.
It has achieved high-quality and excellent single crystal growth, reduced defect density, improved the quality and performance of the film, and has simple process, low cost and good compatibility.
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Figure CN119913613B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of photodetectors, and particularly to a semiconductor single crystal thin film, a preparation method thereof, and a photodetector. Background Art
[0002] With the continuous progress of technology, semiconductor single crystal thin films are increasingly widely used in optoelectronic devices, such as photodetectors, solar cells, light-emitting diodes, etc. However, traditional semiconductor single crystal thin film growth technologies face many challenges when dealing with non-layered materials or materials with a large lattice mismatch with the substrate. For example, direct growth often results in a large number of defects in the thin film, affecting its performance and application effect, while using buffer layer lattice matching can effectively avoid the above situation.
[0003] Although existing buffer layer technologies can improve the quality of thin films, they have limitations. Some buffer layer materials have a low lattice matching degree with semiconductor thin films, resulting in many defects during epitaxial growth. At the same time, traditional buffer layer preparation processes are complex, costly, and have insufficient compatibility with mainstream semiconductor processes, restricting their application scope.
[0004] Therefore, finding a buffer layer technology with a 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, a preparation method thereof, and a photodetector, specifically a method for growing a semiconductor single crystal thin film assisted by a PbS buffer layer and a photodetector.
[0006] The technical solution of the present invention is as follows:
[0007] The first aspect of the present invention provides a semiconductor single crystal thin film, including a substrate, a PbS buffer layer grown on the substrate, and a semiconductor single crystal layer grown on the PbS buffer layer;
[0008] The PbS buffer layer is formed by continuously growing on the surface of the substrate using a PbS single crystal block layer as a raw material.
[0009] Optionally, the thickness of the PbS single crystal block layer is 1 micrometer - 10 micrometers, preferably 2 micrometers - 5 micrometers, to ensure that it can be fully epitaxially grown on the substrate without residue, reducing contamination for the subsequent growth of the semiconductor single crystal thin film.
[0010] Optionally, the thickness of the PbS buffer layer is 5 nanometers - 50 nanometers.
[0011] Optionally, the PbS single-crystal block layer is a PbS single-crystal block layer grown on a substrate. Specifically, a 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).
[0012] Optionally, the semiconductor single-crystal layer and the PbS buffer layer are formed in the same preparation method. By controlling the heating temperature, PbS single crystals are continuously grown on the surface of the substrate to form the PbS buffer layer first, and then semiconductor single crystals are continuously grown on the PbS buffer layer to form the semiconductor single-crystal layer.
[0013] Specifically, the method for preparing the PbS buffer layer on the substrate and the method for growing the 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.
[0014] 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.
[0015] Optionally, the semiconductor single-crystal layer is at least one of a SeSn single-crystal layer and a PbSnTe single-crystal layer. The thickness of the semiconductor single-crystal layer is 0.5 μm to 1 μm. Preferably, the thickness of the PbSnTe single-crystal layer is 0.7 μm - 1 μm, which can be adjusted according to specific application requirements to achieve effective detection of infrared light in different bands.
[0016] Optionally, the substrate is strontium titanate with a crystal orientation of (100).
[0017] The second aspect of the present invention provides a method for preparing a semiconductor single-crystal thin film, including the following steps:
[0018] S1. Grow a PbS single-crystal block layer on the surface of a substrate by physical vapor deposition or chemical vapor deposition to obtain a substrate with a PbS single-crystal block layer grown thereon;
[0019] S2. Along the flow direction of the carrier gas, place the raw materials for preparing the semiconductor single-crystal layer, the substrate with the PbS single-crystal block layer grown thereon, and the substrate in a chemical vapor deposition device in sequence. Control the heating temperature. The vapor formed by the PbS single-crystal block layer is transported by the carrier gas to the surface of the substrate to form a PbS buffer layer, and then the vapor formed by the raw materials for preparing the semiconductor single-crystal layer is transported by the carrier gas to the surface of the PbS buffer layer to form a semiconductor single-crystal layer.
[0020] Optionally, the specific steps of S1 include:
[0021] Place the PbS powder, S powder and substrate in the equipment, evacuate the equipment to 5×10 -4 Pa - 2×10 -3 Pa, then heat up, keep the temperature, and finally cool down. The vapor formed by the PbS powder and the S powder evaporates onto the substrate, and a PbS single crystal block layer is formed on the surface of the substrate;
[0022] Among them, the heating temperature of the PbS powder is 500°C - 700°C, the heating rate ≤ 10°C / min, and the time from room temperature to the heating temperature of the PbS powder is 50 min - 60 min;
[0023] The heating temperature of the S powder is 200°C - 300°C, and the heating rate ≤ 5°C / min;
[0024] The heating temperature of the substrate is 200°C - 300°C;
[0025] The time for keeping the temperature is 5 min - 7 min.
[0026] Optionally, the specific steps of S2 include:
[0027] Along the flow direction of the carrier gas, place the raw materials for preparing the semiconductor single crystal layer, the substrate with the PbS single crystal block layer grown on it, and the substrate in turn from the central position to the tail of the chemical vapor deposition equipment, evacuate, then heat up, keep the temperature, and finally cool 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 materials for preparing the semiconductor single crystal layer continuously grows on the surface of the PbS buffer layer to form a semiconductor single crystal layer.
[0028] Optionally, in S2,
[0029] The raw materials for preparing the semiconductor single crystal layer are a mixture of SnTe powder and Pb powder with a mass ratio of 4 - 6:5 - 7, or a mixture of SnSe powder and Se powder with a mass ratio of 1 - 2:2 - 4;
[0030] The heating temperature of the raw materials for preparing the semiconductor single crystal layer is 700°C - 800°C, the heating rate ≤ 10°C / min, and the time from room temperature to this heating temperature is 70 min - 80 min;
[0031] The heating temperature of the substrate with the PbS single crystal block layer grown on it is 500°C - 600°C, and the heating rate ≤ 10°C / min;
[0032] The heating temperature of the substrate is 200°C - 300°C;
[0033] The heat preservation time is 3 min - 15 min;
[0034] Vacuum is pumped to a vacuum degree of 2 Pa - 4 Pa, and the carrier gas flow rate is controlled to be 100 sccm - 250 sccm.
[0035] The third aspect of the present invention provides a photodetector, including the semiconductor single crystal thin film as described above or the semiconductor single crystal thin film obtained by the preparation method as described above.
[0036] The present invention has at least one of the following beneficial effects:
[0037] 1. The present invention uses PbS as a buffer layer to grow on a substrate, and then grows a semiconductor single crystal layer on this buffer layer, which helps to obtain a semiconductor thin film with high quality and excellent crystallinity, thereby solving the problems such as lattice mismatch in directly growing a semiconductor thin film on a substrate, resulting in a large number of defects in the thin film. Moreover, in the present invention, a PbS single crystal block layer is first grown on a substrate, and then, using the PbS single crystal block layer grown on the substrate surface as a raw material, the raw material is continuously grown on the substrate surface by chemical vapor deposition to form the PbS buffer layer, and then a semiconductor single crystal layer is grown on the PbS buffer layer. Compared with directly growing a semiconductor single crystal layer 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, facilitating the control of its thickness for the next processing, thereby improving the quality and performance of the thin film.
[0038] 2. The present invention utilizes the temperature gradient generated by the uneven heating of the tube furnace during the chemical vapor deposition process to simultaneously realize the continuous growth of the PbS buffer layer and the semiconductor single crystal layer in the same preparation method. This not only effectively reduces the heating time, lowers the cost, 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 thin film. The photodetector prepared based on this technology has higher sensitivity and response speed, and can be widely applied to fields such as infrared detection. Description of the Drawings
[0039] Figure 1 It is a flow chart of the method for growing a semiconductor single crystal thin film assisted by a PbS buffer layer in Embodiments 1 - 2 of the present invention;
[0040] Figure 2 It is a schematic diagram of the method for continuously growing a PbS buffer layer and a semiconductor single crystal thin film by utilizing the temperature gradient in Embodiments 1 - 2 of the present invention;
[0041] Figure 3Scanning electron microscope surface morphology diagrams 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; where, a is the scanning electron microscope surface morphology diagram of PbSnTe grown with a PbS buffer layer in Example 1, and b is the scanning electron microscope surface morphology diagram of PbSnTe grown without a PbS buffer layer in Comparative Example 1;
[0042] Figure 4 Scanning electron microscope side morphology diagrams of the PbSnTe thin film obtained by continuously growing a PbS buffer layer and PbSnTe in Example 1 of the present invention and the scanning electron microscope side morphology diagram of the PbSnTe thin film directly grown on the surface of a PbS single crystal block layer in Comparative Example 2; where, a corresponds to Example 1 and b corresponds to Comparative Example 2;
[0043] Figure 5 X-ray diffraction patterns of the PbSnTe thin film obtained by continuously growing a PbS buffer layer and PbSnTe in Example 1 of the present invention and the X-ray diffraction pattern of the PbSnTe thin film grown using a PbS single crystal block layer in Comparative Example 2; where, a corresponds to Comparative Example 2 and b corresponds to Example 1;
[0044] Figure 6 Energy spectrometer test results of the PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention.
[0045] Figure 7 Optical microscope image of the PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention;
[0046] Figure 8 Long-wave infrared detection performance characterization of PbSnTe grown with a PbS buffer layer in Example 1 of the present invention. Detailed implementation manners
[0047] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to 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.
[0048] Example 1
[0049] This example provides a method for growing a PbSnTe single crystal thin film assisted by a PbS buffer layer, specifically including the following steps:
[0050] The chemical vapor growth process schematic diagram of growing a PbSnTe single crystal thin film assisted by a PbS buffer layer is as Figure 1 shown, and the schematic diagram of the continuous growth method of a PbS buffer layer and a semiconductor single crystal thin film using a temperature gradient is as Figure 2 shown. The specific steps include:
[0051] (1) Growing a PbS single crystal block layer.
[0052] 0.2 g of PbS (99.99%) powder is placed as an evaporation source material on a heat source, and 0.4 g of sulfur powder is placed as a supplementary source at another heat source. Both the PbS and sulfur powder are located at the bottom of the high-temperature furnace; a commercially available strontium titanate substrate with a crystal orientation of (100) plane is set at the upper part of the high-temperature furnace. After sealing the high-temperature furnace, it is evacuated to 5×10 -4 Pa using a mechanical pump and a molecular pump.
[0053] The heating temperature of the sulfur powder supplementary source is 300 °C, the heating temperature of the PbS powder is set at 500 °C, the heating rate is 10 °C / min, the heating temperature of the strontium titanate substrate is set at 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 min. After the vapor formed by the PbS powder and the sulfur powder supplementary source evaporates onto the surface of the strontium titanate substrate and reacts for 6 min, the heating power supply of the high-temperature furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a 2-μm-thick PbS single crystal block layer grown on the surface of the strontium titanate substrate.
[0054] (2) Continuous growth of a PbS buffer layer and a PbSnTe single crystal layer.
[0055] As Figure 2As shown, on the basis of a strontium titanate substrate on which a PbS single crystal block layer has been grown, along the flow direction of the carrier gas (argon) from upstream to downstream, 0.2 g of SnTe (99.999%) and 0.2 g of Pb (99.999%) are mixed as evaporation source materials and placed at 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 arranged at the end of the furnace, 10 cm away from the outlet, and the substrate strontium titanate is arranged at the end of the furnace, 3 cm away from the outlet; after the tube furnace is sealed, it is evacuated to a vacuum degree of 2 Pa by a mechanical pump, and the carrier gas flow rate is controlled at 100 sccm. The heating temperature of the evaporation source materials is set at 780 °C, the heating rate is 10 °C / min, the heating temperature of the PbS single crystal block layer along the temperature gradient is 550 °C, the heating rate is 10 °C / min, the heating temperature of the substrate strontium titanate is set at 250 °C, and the heating rate is 10 °C / min; the time for the tube furnace to be heated from room temperature to the heating temperature of the evaporation source materials (780 °C) is 78 min. The vapor formed first by heating the PbS single crystal block layer grown on the strontium titanate substrate is transported by the carrier gas to the surface of the substrate strontium titanate for reaction for 30 s, and a PbS buffer layer is continuously grown on the surface of the substrate strontium titanate; then, the vapor formed by heating the evaporation source is transported by the carrier gas to the surface of the substrate strontium titanate with the PbS buffer layer formed for reaction for 5 min, and a PbSnTe single crystal layer is continuously grown on the PbS buffer layer. The heating power supply of the tube furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a PbSnTe single crystal thin film.
[0056] Comparative Example 1
[0057] The difference from Example 1 is only that: step (1) is not carried out, and in step (2), there is no need to add a strontium titanate substrate on which a PbS single crystal block layer has been grown, and a PbSnTe single crystal thin film is directly grown on the surface of the substrate strontium titanate, and other steps are the same as those in Example 1.
[0058] Comparative Example 2
[0059] The difference from Example 1 is only that: in step (2), there is no need to add the substrate strontium titanate, and a PbSnTe single crystal layer is directly grown continuously on the surface of the strontium titanate substrate on which the PbS single crystal block layer has been grown in step (1).
[0060] Perform performance tests on the PbSnTe thin film with a PbS buffer layer grown in Example 1 and the PbSnTe thin films prepared in Comparative Example 1 and Comparative Example 2. The test results are as follows:
[0061] Figure 3 This is the scanning electron microscope surface morphology diagram of growing PbSnTe with a PbS buffer layer in Example 1 of the present invention and growing PbSnTe without a PbS buffer layer in Comparative Example 1; it can be seen from the figure that the PbSnTe thin film grown with a PbS buffer layer prepared in Example 1 ( Figure 3a) in [it] is significantly better than the PbSnTe thin film grown without a PbS buffer layer prepared in Comparative Example 1 ( Figure 3 b) in [it]. This indicates 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 and at the same time ensures that it can meet a requirement for light detection of the single crystal thin film.
[0062] Figure 4 This is the SEM side morphology diagram of the PbSnTe thin film obtained by continuously growing the PbS buffer layer and PbSnTe in Example 1 of the present invention and the SEM side morphology diagram of the PbSnTe thin 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 known that the thickness of the PbSnTe thin film obtained by continuously growing the PbS buffer layer and PbSnTe is only 0.71 μm ( Figure 4 a) in [it], while the total thickness of the PbSnTe thin film directly grown on the surface of the PbS single crystal block layer is about 2.3 - 6 μm ( Figure 4 b) in [it]. This indicates that by the method of continuously growing the PbS buffer layer and PbSnTe to obtain the PbSnTe thin film, it helps to reduce the surface thickness of PbSnTe and the thickness of the PbS buffer layer, and is convenient for controlling its thickness for the next processing.
[0063] Figure 5 This is the X-ray diffraction pattern of the PbSnTe thin film obtained by continuously growing the PbS buffer layer and PbSnTe in Example 1 of the present invention ( Figure 5 b) in [it] and the X-ray diffraction pattern of the PbSnTe thin film directly grown using the surface of the PbS single crystal block layer in Comparative Example 2 ( Figure 5 a) in [it]; it can be seen from the figure that both growth methods can obtain PbSnTe thin films with good single crystal properties, but the characteristic peak positions of the PbS crystal can be clearly seen in the PbSnTe thin film directly grown using the surface of the PbS single crystal block layer, which further indicates that its thickness is too large.
[0064] Figure 6 This is the energy spectrometer test result of the PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention. It can be known from the data in the figure that the element distribution is uniform.
[0065] Figure 7 This is the light microscope image of the PbSnTe single crystal thin film grown with a PbS buffer layer in Example 1 of the present invention; combined with the SEM image, it can be seen that its texture is uniform and has the luster of a semiconductor thin film.
[0066] Figure 8Characterization of the long-wave infrared detection performance of PbSnTe grown with a PbS buffer layer in Example 1 of the present invention. From the characterization results, it can be seen that the PbSnTe device grown with a PbS buffer layer can still achieve a microvolt-level optoelectronic response under the condition of a micro-watt-level optical power, demonstrating its reliability in the field of infrared optoelectronic detection.
[0067] Example 2
[0068] This example provides a method for assisting the growth of SnSe single crystal thin films with a PbS buffer layer, specifically including the following steps:
[0069] The schematic diagram of the chemical vapor growth process for assisting the growth of SnSe single crystal thin films with a PbS buffer layer is as Figure 1 shown, including:
[0070] (1) Growing a PbS single crystal block layer.
[0071] 0.2 g of PbS (99.99%) powder is placed as an evaporation source material on a heat source, and 0.4 g of sulfur powder is placed as a supplementary source at another heat source, both located at the bottom of the high-temperature furnace; the purchased strontium titanate substrate with a crystal orientation of (100) plane is set at the upper part of the high-temperature furnace. After sealing the high-temperature furnace, it is evacuated to 5×10 -4 Pa using a mechanical pump and a molecular pump.
[0072] The heating temperature of the sulfur powder supplementary source is 300 °C, the heating temperature of the PbS powder is set at 500 °C, the heating rate is 10 °C / min, the heating temperature of the strontium titanate substrate is set at 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 min. After the vapor formed by the PbS powder and the sulfur powder supplementary source evaporates to the surface of the strontium titanate substrate and reacts for 6 min, the heating power supply 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.
[0073] (2) Continuous growth of the PbS buffer layer and the SnSe single crystal layer.
[0074] As Figure 2As shown in the figure, on the basis of a strontium titanate substrate on which a PbS single crystal block layer has been grown, along the flow direction of the carrier gas from upstream to downstream, 0.1 g of SnSe (99.999%) and 0.2 g of Se (99.999%) are mixed as evaporation source materials and placed at the center of a 2-inch diameter horizontal tube furnace; the PbS single crystal block layer is arranged at the end of the furnace, 10 cm away from the outlet, and the substrate strontium titanate is arranged at the end of the furnace, 3 cm away from the outlet. After sealing the tube furnace, it is evacuated to a vacuum degree of 2 Pa by a mechanical pump, and the carrier gas flow rate is controlled at 100 sccm. The heating temperature of the evaporation source materials is set at 700 °C, and the heating rate is 10 °C / min. Along the temperature gradient, the temperature of the PbS single crystal block layer is 550 °C, and the heating rate is 10 °C / min. The temperature of the substrate strontium titanate is set at 250 °C, and the heating rate is 10 °C / min. The time for the tube furnace to be heated from room temperature to the heating temperature of the evaporation source materials (700 °C) is 70 min. First, the vapor formed by the PbS single crystal block layer is transported by the carrier gas to the surface of the strontium titanate substrate for reaction for 1 min, and then the vapor formed by the reaction source is transported by the carrier gas to the surface of the strontium titanate substrate for reaction for 5 min. After that, the heating power supply of the tube furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a SnSe single crystal thin film.
[0075] Comparative Example 3
[0076] The difference from Example 2 is only that: step (1) is not carried out, and in step (2), there is no need to add a strontium titanate substrate with a grown PbS single crystal block layer, and the SnSe single crystal thin film is directly grown on the surface of the strontium titanate substrate. Other steps are the same as in Example 1.
[0077] Comparative Example 4
[0078] The difference from Example 2 is only that: in step (2), there is no need to add a strontium titanate substrate, and the SnSe single crystal thin film is directly grown continuously on the surface of the strontium titanate substrate with a grown PbS single crystal block layer in step (1).
[0079] Perform performance tests on the SnSe single crystal thin film with a PbS buffer layer grown in Example 2 and the SnSe single crystal thin films prepared in Comparative Example 3 and Comparative Example 4. The test results are similar to those in Example 1, Comparative Example 2, and Comparative Example 3. That is, the surface density of the SnTe thin film grown with a PbS buffer layer prepared in Example 2 is 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 the substrate and then growing a semiconductor single crystal (SnTe) thin film on the PbS buffer layer, it helps to make the growth orientation of SnTe consistent and at the same time ensures that the requirements for light detection of the single crystal thin film can be met.
[0080] Similarly, in Example 2, the SnTe thin film was obtained by continuously growing the PbS buffer layer and SnTe. Compared with Comparative Example 4, the thickness of the obtained SnTe thin film was thinner, indicating that the method of the present invention helps to reduce the surface thickness of SnTe and the thickness of the PbS buffer layer, facilitating the control of its thickness for the next processing step.
[0081] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within 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 block layer as a raw material; 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; 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; The semiconductor single crystal layer is at least one of a SeSn single crystal layer and a PbSnTe single crystal layer; the substrate is strontium titanate; The method for preparing the semiconductor single crystal thin film comprises 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.
2. The semiconductor single crystal thin film according to claim 1, 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.
3. The semiconductor single crystal thin film according to claim 1, 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.
4. The semiconductor single crystal thin film according to claim 3, 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.
5. A photoelectric detector, characterized in that: Comprising the semiconductor single crystal thin film as described in any one of claims 1 to 4.