Bismuth tellurium sulfide semiconductor, preparation method and optoelectronic device

Abstract

The invention discloses a bismuth tellurium sulfide semiconductor, a preparation method and a photoelectric device. The bismuth tellurium sulfide semiconductor is a crystal, and the chemical structure of the bismuth tellurium sulfide semiconductor is Bi x Te y S z , where 1≤x≤2, 0<y≤3, 0<z≤3. In the above-mentioned bismuth telluride semiconductor, Bi 2 Te 3 The semiconductor has an orthorhombic structure. By doping S into Bi 2 Te 3 In the middle, Bi x Te y S z Semiconductor. Compared with Bi 2 Te 3 Semiconductor, Bi x Te y S z The energy band structure of the semiconductor is optimized and enriched; therefore, the optoelectronic devices constructed with it have lower dark current and wider detection range, which helps to achieve high performance of the optoelectronic devices.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a bismuth tellurium sulfide semiconductor, a preparation method and a photoelectric device. Background Art

[0002] The topological insulator bismuth telluride has attracted the attention of a large number of researchers for its unique optical and electrical properties. Bismuth telluride has a narrow band gap of about 0.3eV. Due to the presence of metallic surface states in its band structure, it has rich physical properties such as ultra-high carrier mobility and extremely low heat loss rate. These characteristics make it a new material with great development prospects. At present, some researchers have conducted preliminary research on bismuth telluride in the field of optoelectronics and believe that it has good performance in high-performance infrared and terahertz detectors.

[0003] For optoelectronic devices, an excellent on-off ratio is a key indicator for detecting their performance. However, the metallic surface states of topological insulators can lead to too high dark current, which reduces the on-off ratio and thus affects the performance of the device. Summary of the invention

[0004] In view of this, the present invention provides a bismuth telluride sulfide semiconductor, a preparation method and an optoelectronic device to solve the technical problem of excessively high dark current of bismuth telluride.

[0005] To achieve the above object, the present invention provides a bismuth tellurium sulfide semiconductor in a first aspect. The bismuth tellurium sulfide semiconductor is a crystal, and the chemical structure of the bismuth tellurium sulfide semiconductor is Bi x Te y S z , where 1≤x≤2, 0<y≤3, 0<z≤3.

[0006] Optionally, in Bi x Te y S z , x=2, 0<y≤3, 0<z≤3.

[0007] Optionally, in Bi x Te y S z In, x=2; y=0.6; z=2.4.

[0008] A second aspect of the present invention provides a method for preparing a bismuth tellurium sulfide semiconductor, comprising the following steps:

[0009] Bismuth powder, tellurium powder and sulfur powder are available.

[0010] Bismuth tellurium sulfide semiconductors are directly grown by chemical vapor transport or hydrothermal-solvothermal synthesis. Bismuth tellurium sulfide semiconductors are directly grown on insulating substrates by chemical vapor deposition, physical vapor deposition, or metal organic source chemical vapor deposition.

[0011] Optionally, the step of directly growing a bismuth tellurium sulfide semiconductor by chemical vapor transport comprises:

[0012] Bismuth powder, tellurium powder, sulfur powder and a conveying medium are mixed and sealed in a quartz tube, and the interior of the quartz tube is a vacuum atmosphere.

[0013] The quartz tube is placed in a dual-temperature zone tube furnace, the first temperature zone is set to 540-580°C, the second temperature zone is set to 480-520°C, and maintained for 1-7 days. Then it is cooled to 200-300°C at a rate of 0.6-1.0°C / min, and then cooled naturally. The temperature difference between the first temperature zone and the second temperature zone is 50-100°C.

[0014] When the temperature of the quartz tube reaches room temperature, the sample is taken out to obtain bismuth tellurium sulfide semiconductor.

[0015] Optionally, the quartz tube is placed in a dual-temperature zone tube furnace, and the first temperature zone is heated to 560°C and the second temperature zone is heated to 500°C at a heating rate of 10°C / min, and maintained for 4 days. Then, the temperature is reduced by 300°C at a rate of 0.8°C / min, and then cooled naturally.

[0016] Optionally, the step of growing a bismuth tellurium sulfide semiconductor directly on an insulating substrate by chemical vapor deposition comprises:

[0017] Bismuth powder, tellurium powder and sulfur powder are placed at the upper end of the tube furnace in the air flow direction.

[0018] The insulating substrate is placed at the lower end of the tube furnace in the air flow direction.

[0019] In an atmosphere of protective gas, the tube furnace is heated to 540-580° C. at a rate of 10-30° C. / min and maintained for 5-20 minutes for chemical vapor deposition to obtain a bismuth tellurium sulfide semiconductor.

[0020] Alternatively, the tube furnace is filled with argon, the temperature is increased to 560° C. at a rate of 20° C. / min, and maintained at this temperature for 10 minutes.

[0021] Optionally, the transport medium is elemental iodine.

[0022] A third aspect of the present invention provides a photoelectric device, comprising a substrate and a semiconductor material disposed on the substrate, wherein the semiconductor material is the above-mentioned bismuth tellurium sulfide semiconductor or the bismuth tellurium sulfide semiconductor prepared by the above-mentioned preparation method.

[0023] Among the above-mentioned bismuth tellurium sulfide semiconductors, Bi2Te3 semiconductor has a trigonal crystal structure. By doping S into Bi2Te3, Bi x Te y S z Semiconductor. Compared with Bi2Te3 semiconductor, Bi xTe y S z The energy band structure of the semiconductor is optimized and enriched; therefore, the optoelectronic devices constructed with it have lower dark current and wider detection range, which helps to achieve high performance of the optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an EDS spectrum of a bismuth tellurium sulfide semiconductor according to an embodiment of the present application;

[0025] Figure 2 A polarized Raman spectrum of a bismuth tellurium sulfide semiconductor according to an embodiment of the present application;

[0026] Figure 3 A schematic diagram of a photodetector according to an embodiment of the present application;

[0027] Figure 4 This is a spectrum detection diagram of a photoelectric detector according to one embodiment of the present application;

[0028] Figure 5 An IV diagram of a photodetector according to an embodiment of the present application;

[0029] Figure 6 FIG. 1 is a response time diagram of a photodetector according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0033] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] The metal surface state of the topological insulator will cause the dark current to be too high, reducing the switching ratio, thus affecting the performance of the device. In the related art, the method of constructing a heterojunction and applying an external field is often used to solve the problem of excessive dark current. However, the method of constructing a heterojunction and applying an external field is technically complex and not conducive to large-scale production. The target material is directly grown by the alloying method, which is simple to operate, highly repeatable, and can be prepared in large quantities. Based on this, the present application provides a bismuth tellurium sulfide semiconductor, a preparation method, and an optoelectronic device to solve the problem of excessive dark current.

[0035] To achieve the above object, an embodiment of the present invention provides a bismuth tellurium sulfide semiconductor, wherein the bismuth tellurium sulfide semiconductor is a crystal, and the chemical structure of the bismuth tellurium sulfide semiconductor is Bi x Te y S z , where 1≤x≤2, 0<y≤3, 0<z≤3.

[0036] Bismuth tellurium sulfide semiconductor is a crystal, and the structure of the crystal includes but is not limited to nanowires, nanorods, quantum dots and nanosheets, etc. And its crystalline state includes but is not limited to single crystal, polycrystalline, microcrystalline and amorphous, etc.

[0037] The chemical formula of bismuth tellurium sulfide semiconductor is Bi x Te y S z , which essentially represents a series of bismuth tellurium sulfide semiconductor materials in which S is doped in Bi2Te3 semiconductor. The specific bismuth tellurium sulfide semiconductor materials have different doping levels, which is reflected in the different x, y and z in the corresponding structural formula. In other words, during the preparation process, different bismuth tellurium sulfide semiconductor materials can be obtained by changing the ratio of bismuth powder, tellurium powder and sulfur powder in the raw materials, thereby changing the ratio of the three elements of bismuth, tellurium and sulfur. In this way, bismuth tellurium sulfide semiconductor materials with different band gaps can be obtained, and then the corresponding wide-band optoelectronic devices can be prepared based on them, which can be specifically applied to wide-band optoelectronic devices from deep ultraviolet to infrared, that is, they can be applied to broad-spectrum, ultrafast polarization photodetectors.

[0038] Among the above-mentioned bismuth tellurium sulfide semiconductors, Bi2Te3 semiconductor has a trigonal crystal structure. By doping S into Bi2Te3, Bi x Te y S z Semiconductor. Compared with Bi2Te3 semiconductor, Bi x Te y Sz The energy band structure of the semiconductor is optimized and enriched; therefore, the optoelectronic devices constructed with it have lower dark current and wider detection range, which helps to achieve high performance of the optoelectronic devices.

[0039] In some embodiments, in Bi x Te y S z , x=2, 0<y≤3, 0<z≤3.

[0040] In some embodiments, in Bi x Te y S z In this case, x = 2, y = 0.6, and z = 2.4. In this case, the bismuth tellurium sulfide semiconductor is a Bi2Te2.15S0.85 crystal.

[0041] A second aspect of the present invention provides a method for preparing a bismuth tellurium sulfide semiconductor, comprising the following steps:

[0042] S100: Provides bismuth powder, tellurium powder and sulfur powder;

[0043] In step S100, the purity of bismuth powder, tellurium powder and sulfur powder is relatively high. For example, bismuth powder may be 99.999% pure, sulfur powder may be 99.999% pure, and tellurium powder may be 99.999% pure.

[0044] S200: Directly grow bismuth tellurium sulfide semiconductors using chemical vapor transport or hydrothermal-solvothermal synthesis; or directly grow bismuth tellurium sulfide semiconductors on insulating substrates using chemical vapor deposition, physical vapor deposition, or metal organic source chemical vapor deposition.

[0045] In step S200 , there are many methods for growing bismuth tellurium sulfide semiconductors, which are not specifically limited.

[0046] In some embodiments, the step of directly growing a bismuth tellurium sulfide semiconductor using chemical vapor transport includes:

[0047] S201: Bismuth powder, tellurium powder, sulfur powder and conveying medium are mixed and sealed in a quartz tube, and the quartz tube is in a vacuum atmosphere.

[0048] In this step, bismuth powder, tellurium powder and sulfur powder can be weighed according to the ratio of each element in the bismuth tellurium sulfur semiconductor and mixed and put into a quartz tube, and then a certain amount of transport medium is added.

[0049] Then use a molecular pump to evacuate the quartz tube containing the above substances to a vacuum, such as 10 -3 Pa, the quartz tube containing the substance is vacuum sealed using an oxyhydrogen machine.

[0050] S202: The quartz tube is placed in a dual-temperature zone tubular furnace, the first temperature zone is set to 540-580°C, the second temperature zone is set to 480-520°C, and the temperature is kept warm for 1-7 days; then the temperature is cooled to 200-300°C at a rate of 0.6-1.0°C / min, and then cooled naturally; wherein the temperature difference between the first temperature zone and the second temperature zone is 50-100°C.

[0051] In this step, the first temperature zone is a high temperature zone (also called a source zone), and the second temperature zone is a low temperature zone (also called a growth zone).

[0052] Bismuth powder, tellurium powder and sulfur powder (the three can be called source materials) are mixed evenly in the first temperature zone under the drive of iodine vapor, and high-quality Bi is generated in the second temperature zone. x Te y S z semiconductor.

[0053] During the growth process, the temperature difference between the low temperature zone and the high temperature zone must be between 50 and 100°C for effective transportation. If the temperature difference between the first temperature zone and the second temperature zone is too high, the crystal will be uneven. If the temperature difference between the first temperature zone and the second temperature zone is too low, the crystal growth cycle will be prolonged or even no growth will occur. Therefore, the first temperature zone is heated to 540-580°C and the second temperature zone is heated to 480-520°C. The insulation time of this step can be 1-2 days, 2-4 days, 5-6 days, 6-7 days, etc.

[0054] The cooling process is divided into the first stage and the second stage. In the first stage, the temperature is cooled to 200-300°C at a rate of 0.6-1.0°C / min. In this stage, the cooling rate is slow, which can avoid the breakage of large crystals during the cooling process and form fine grains. In other words, the slow cooling rate can ensure the integrity of the large crystals grown during the insulation process, so that the volume of the grains is larger, which can enhance the toughness of the crystals and ensure the quality of the crystals.

[0055] In the second stage, natural cooling is performed. The heating mechanisms corresponding to the first and second temperature zones are turned off. The quartz tube is in the furnace and is cooled along with the furnace. At temperatures below 300°C, crystal growth is complete. Natural cooling can quickly reduce the temperature and ensure that the quality of the crystal is not affected, thereby improving the production efficiency of bismuth telluride sulfide semiconductors.

[0056] S203: When the temperature of the quartz tube reaches room temperature, take out the sample to obtain a bismuth tellurium sulfide semiconductor.

[0057] In some embodiments, the quartz tube is placed in a dual-temperature zone tubular furnace, and the first temperature zone is heated to 560°C at a heating rate of 10°C / min, and the second temperature zone is heated to 500°C, and kept warm for 4 days; then, the temperature is lowered by 300°C at a rate of 0.8°C / min, and then naturally cooled.

[0058] Under the condition of this heating rate, effective transport of the precursor can be guaranteed and the chemical reaction can be sufficient; if the heating rate is too fast, it will lead to the formation of small grains and an increase in crystal defects; if the heating rate is too slow, the growth rate of the crystal will decrease, reducing the growth efficiency.

[0059] In some embodiments, the transport medium is elemental iodine.

[0060] In some embodiments, a step of removing the transport medium in the growth material in the quartz tube may be further included, the step comprising:

[0061] The sample taken out of the quartz tube was placed in a tube furnace with protective gas and annealed at 150° C. for 5 hours.

[0062] In some embodiments, the step of growing a bismuth tellurium sulfide semiconductor directly on an insulating substrate by chemical vapor deposition includes:

[0063] S301: Bismuth powder, tellurium powder and sulfur powder are placed at the upper end of the air flow direction of the tube furnace.

[0064] In step S301, bismuth powder, tellurium powder and sulfur powder may be weighed and mixed according to the ratio of each element in the bismuth tellurium sulfur semiconductor and then placed in a quartz boat. The quartz boat containing the raw materials is placed at the upper end of the airflow of the tube furnace.

[0065] S302: The insulating substrate is placed at the lower end of the tube furnace in the air flow direction.

[0066] In step S302, an insulating substrate is placed at the lower end of the tube furnace to prepare for material growth.

[0067] S303: In an atmosphere of protective gas, the tube furnace is heated to 540-580° C. at a rate of 10-30° C. / min, and kept at this temperature for 5-20 minutes to perform chemical vapor deposition to obtain a bismuth tellurium sulfide semiconductor.

[0068] In step S303, the tubular furnace is filled with a protective gas atmosphere. The protective gas may be argon. High-purity argon may be introduced at a relatively large flow rate for half an hour to remove the air in the tubular furnace, and then argon may be continuously introduced at a relatively small flow rate. The tubular furnace is heated to 680 to 720°C at a rate of 10 to 30°C / min and kept warm for 5 to 20 minutes. In this process, the bismuth powder, tellurium powder and sulfur powder at the upper end of the tubular furnace gas flow form corresponding gases, which are deposited on the insulating substrate as the argon flows to the lower end of the tubular furnace to grow and form a bismuth tellurium sulfur semiconductor. After the growth is completed, the tubular furnace may be naturally cooled to room temperature, and then the bismuth tellurium sulfur semiconductor may be taken out.

[0069] It should be noted that the quantity and form of the deposited products will be different if the temperature rises too slowly or too quickly, or if the temperature of the tube furnace is high or low. For example, if the bismuth telluride sulfide crystals are in the state of nanowires, the nanowires are too thick / too thin or the number is too small, the uniformity of the sample will be reduced, which will directly affect its electronic band structure and will inevitably affect the performance.

[0070] Exemplarily, the tube furnace is filled with argon gas, the temperature is increased to 560° C. at a rate of 20° C. / min, and the temperature is maintained for 10 minutes.

[0071] A third aspect of the present invention provides a photoelectric device, comprising a substrate and a semiconductor material disposed on the substrate, wherein the semiconductor material is the above-mentioned bismuth tellurium sulfide semiconductor or the bismuth tellurium sulfide semiconductor prepared by the above-mentioned preparation method.

[0072] For example, a Bi x Te y S z The semiconductor photodetector includes, from bottom to top, a substrate, a Bi x Te y S z Semiconductor and metal electrode. In some embodiments, the substrate is SiO2 / Si substrate, mica substrate or sapphire substrate. In some embodiments, Bi x Te y S z The crystal form of the semiconductor is nanowires, nanorods, quantum dots and nanosheets. In some embodiments, Bi x Te y S z The thickness of the electrode layer is 0.1-500 nm. In some embodiments, the thickness of the electrode layer is 50-100 nm.

[0073] Example 1: Directly growing bismuth tellurium sulfide semiconductors using chemical vapor transport.

[0074] Bi2Te was prepared by chemical vapor transport. 0.6 S 2.4 Semiconductor crystal, the specific preparation method is as follows:

[0075] Step a: bismuth powder, tellurium powder, sulfur powder and a conveying medium are mixed and sealed in a quartz tube, wherein the quartz tube is in a vacuum atmosphere.

[0076] The bismuth powder is 99.999% pure bismuth powder, the sulfur powder is 99.999% pure sulfur powder, and the tellurium powder is 99.999% pure tellurium powder. The bismuth powder, tellurium powder and sulfur powder are mixed in a total amount of 1 gram in a quartz tube according to a molar ratio of Bi:Te:S=2:0.6:2.4 in the bismuth tellurium sulfur semiconductor, and 5 mg / mL iodine is added as a transport medium.

[0077] Then use a high vacuum system to evacuate the quartz tube containing the above substances to a vacuum, such as 10 -3 Pa or above, a high temperature flame is used to vacuum seal the quartz tube containing the substance.

[0078] Step b: Place the quartz tube in a dual-temperature zone tube furnace, set the first temperature zone to 560°C, and the second temperature zone to 500°C, keep warm for 3 days, then cool to 300°C at a rate of 0.8°C / min, and then cool naturally.

[0079] Step c: When the temperature of the quartz tube reaches room temperature, take out the sample to obtain a bismuth tellurium sulfide semiconductor.

[0080] See also Figure 1 , characterized by EDS (dispersion spectrum) energy spectrum as Bi2Te 0.6 S 2.4 Nanowire single crystal.

[0081] See also Figure 2 , which was characterized by polarized Raman spectroscopy to be Bi2Te 0.6 S 2.4 Nanowires are single crystal and anisotropic.

[0082] Example 2: Directly growing bismuth tellurium sulfide semiconductors using chemical vapor transport.

[0083] Bi2Te was prepared by chemical vapor transport. 0.85 S 2.15 Semiconductor crystal, the specific preparation method is as follows:

[0084] Step a is different from Example 1 in that the molar ratio of bismuth powder, tellurium powder and sulfur powder is Bi:Te:S=2:0.85:2.15, and the rest is the same as Example 1.

[0085] Step b: Place the quartz tube in a dual-temperature zone tube furnace, set the first temperature zone to 540°C, and the second temperature zone to 480°C, keep warm for 7 days, then cool to 250°C at a rate of 0.6°C / min, and then cool naturally.

[0086] Step c: Same as Example 1.

[0087] Example 3: Directly growing bismuth tellurium sulfide semiconductors using chemical vapor transport.

[0088] Bi2Te1S2 semiconductor crystals were prepared by chemical vapor transport method, and the specific preparation method is as follows:

[0089] Step a is different from Example 1 in that the molar ratio of bismuth powder, tellurium powder and sulfur powder is Bi:Te:S=2:1:2, and the rest is the same as Example 1.

[0090] Step b: Place the quartz tube in a dual-temperature zone tube furnace, set the first temperature zone to 580°C, and the second temperature zone to 520°C, keep warm for 1 day, then cool to 300°C at a rate of 0.8°C / min, and then cool naturally.

[0091] Step c: Same as Example 1.

[0092] Example 4: Directly growing bismuth tellurium sulfide semiconductors using chemical vapor transport.

[0093] Bi2Te was prepared by chemical vapor transport. 0.4 S 2.6 Semiconductor crystal, the specific preparation method is as follows:

[0094] Step a is different from Example 1 in that the molar ratio of bismuth powder, tellurium powder and sulfur powder is Bi:Te:S=2:0.4:2.6, and the rest is the same as Example 1.

[0095] Step b: Place the quartz tube in a dual-temperature zone tube furnace, set the first temperature zone to 550°C, and the second temperature zone to 490°C, keep warm for 3 days, then cool to 280°C at a rate of 0.8°C / min, and then cool naturally.

[0096] Step c: Same as Example 1.

[0097] Embodiment 5: Growing bismuth tellurium sulfide semiconductor on an insulating substrate by chemical vapor deposition.

[0098] Bi2Te was prepared by chemical vapor deposition. 1.2 S 1.8 Semiconductor crystal, the specific preparation method is as follows:

[0099] Step a: Weigh 1 gram of Bi powder with a purity of 99.999%, sulfur powder with a purity of 99.999%, and tellurium powder with a purity of 99.999%, and place them in a quartz boat at a molar ratio of Bi:Te:S=2:1.2:1.8.

[0100] Step b, placing the quartz boat at the upper end of the airflow of the tube furnace.

[0101] Step c: placing an insulating substrate at the lower end of the tube furnace to prepare for material growth.

[0102] Step d: introducing high-purity argon gas for half an hour to remove oxygen in the tube furnace.

[0103] Step e: with a relatively small argon flow rate, raise the temperature to 560°C at a rate of 20°C / min, and keep at this temperature for 10 minutes.

[0104] Step f: After the growth is completed, the mixture is cooled naturally to room temperature to obtain Bi2Te1.2 S 1.8 semiconductor.

[0105] Example 6: Bi x Te y S z Method for preparing photoelectric detector based on

[0106] Using Bi2Te of Example 1 0.6 S 2.4 Semiconductor crystals are used to make photodetectors. The specific preparation method is as follows:

[0107] Step a: grow Bi2Te 0.6 S 2.4 Nanowires are transferred directly onto SiO2 by pressing and dragging with tweezers.

[0108] Step b: Through gold plating or photolithography, on Bi2Te 0.6 S 2.4 The two ends of the nanowire are covered with metal electrodes. 0.6 S 2.4 The area not covered by the nanowire is the photosensitive area of ​​the photodetector. 0.6 S 2.4 The schematic diagram of the basic photodetector structure is as follows Figure 3 Shown: electrode 11, Bi2Te 0.6 S 2.4 Nanowire 12, SiO2 layer 13, Si 14.

[0109] Test Example

[0110] Take the Bi2Te of Example 6 0.6 S 2.4 The photodetector based on this was tested.

[0111] The above photodetector was placed in a self-built probe station, and the two ends of the power supply were connected to the two electrodes in contact with the material using probes. The photocurrent of the device was tested using lasers of different wavelengths. The light response range was 254nm-1064nm. The results are as follows: Figure 4 shown.

[0112] The above photodetector is illuminated by a 405nm semiconductor laser and the current-voltage relationship is tested under the probe station. The test results are as follows Figure 5 As shown in the figure, the current-voltage curve is symmetrical about the origin, which shows that the Bi2Te 0.6 S 2.4 It is in ohmic contact with the metal electrode. Adjust the output power of the laser. At the same voltage, the current value changes with the optical power, indicating that the photodetector has a large light response.

[0113] The above-mentioned photodetector is irradiated with periodically changing laser pulses through a waveform generator (Keysight Technologies, 33612A) to test the changing pattern of the response voltage. The test results are as follows: Figure 6 As shown, the response time is 1 μs.

[0114] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a bismuth tellurium sulfide semiconductor, characterized in that: The following steps are involved: Provide bismuth powder, tellurium powder and sulfur powder; the ratio of bismuth powder, tellurium powder and sulfur powder meets Bi x Te y S z The chemical structure requirements are: x=2; y=0.6; z=2.4; Bismuth tellurium sulfide semiconductor is directly grown by chemical vapor transport; the steps of directly growing the bismuth tellurium sulfide semiconductor by chemical vapor transport include: The bismuth powder, the tellurium powder, the sulfur powder and the conveying medium are mixed and sealed in a quartz tube, and the quartz tube is in a vacuum atmosphere; The quartz tube is placed in a dual-temperature zone tube furnace, the first temperature zone is set to 540-580°C, the second temperature zone is set to 480-520°C, and maintained for 1-7 days; then cooled to 200-300°C at a rate of 0.6-1.0°C / min, and then cooled naturally; wherein the temperature difference between the first temperature zone and the second temperature zone is 50-100°C; When the temperature of the quartz tube reaches room temperature, the sample is taken out to obtain a bismuth tellurium sulfide semiconductor.

2. The method for preparing a bismuth tellurium sulfide semiconductor according to claim 1, characterized in that: The quartz tube was placed in the dual-temperature zone tubular furnace, and the first temperature zone was heated to 560°C at a heating rate of 10°C / min, and the second temperature zone was heated to 500°C, and maintained for 4 days; then, the temperature was reduced by 300°C at a rate of 0.8°C / min, and then naturally cooled.

3. The method for preparing a bismuth tellurium sulfide semiconductor according to claim 1, characterized in that: The transport medium is iodine element.

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