Preparation method and device of n-type bismuth telluride thermoelectric thick film

Abstract

The invention provides a preparation method and device of an n-type bismuth telluride thermoelectric thick film. The method comprises the following steps: obtaining an aluminum nitride substrate; magnetron sputtering parameters are preset; performing magnetron sputtering treatment on the aluminum nitride substrate by using a bismuth telluride target and a tellurium target according to the magnetron sputtering parameters to obtain a first thermoelectric thick film; and carrying out stepped temperature raising treatment on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film. According to the method, the n-type bismuth telluride thermoelectric thick film is prepared in a mode of combining stepped temperature raising with step-by-step in-situ annealing and applying bias voltage to the substrate, directional controllable growth in the (001) direction is achieved, the thickness of the prepared thermoelectric thick film exceeds 10 micrometers, and the thermoelectric figure of merit ZT value exceeds 1.1.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoelectric materials, and in particular relates to a method and a device for preparing an n-type bismuth telluride thermoelectric thick film. Background Art

[0002] With the acceleration of 5G base station construction, the demand for optical modules has increased significantly. In the future, there will be a demand to fully upgrade medium- and high-speed optical modules below 100G to above 400G. By then, the heat generation power of the core parts of the key modules will rise to 100W / cm 2 , urgently requiring the development of fast, high-precision, active targeted temperature control technology. Existing conventional dielectric and mechanical one-way thermal control technologies can no longer meet the above application requirements. All-solid-state thermoelectric technology based on the Peltier effect has the advantages of high power density and fast response speed, and can achieve fast and accurate temperature control. Due to the application requirements of lightness and high-efficiency point temperature control, the current commercial block thermoelectric coolers (size of the order of 1 to 10 cm) can no longer fully meet the requirements for cooling the above electronic devices. Thermoelectric devices are developing towards miniaturization (size of the order of 0.1 to 1 cm) and high integration of thermoelectric arms (thickness of the order of 10 microns).

[0003] Bismuth telluride-based materials are the best thermoelectric materials in the near-room temperature range, and are also the only room-temperature thermoelectric materials that have been put into commercial use. At present, most commercial thermoelectric devices use zone melting technology to produce bismuth telluride-based alloys, and then use a "top-down" cutting method to thin the thermoelectric arms. Constrained by the large single crystal structure, bismuth telluride-based thermoelectric materials are not strong enough, and the traditional cutting process is prone to secondary damage to the material, making it impossible to further reduce the size of the thermoelectric arm (generally greater than 300μm), resulting in the inability to increase the number of thermoelectric arms per unit area, resulting in a low cooling power density of the thermoelectric device, which is only 10 to 20W / cm 2 , which cannot meet the application requirements of high-frequency optical modules in terms of rapid temperature control and future miniaturization and lightweight.

[0004] Ternary Bi2Te 2.7 Te 0.3 It is a commonly used n-type thermoelectric material. The key to using magnetron sputtering to prepare thermoelectric thick films with good performance is to achieve directional and controllable growth of the thick film in the (00l) direction (layered). However, the thickness of thermoelectric films with good performance prepared by current researchers is generally within 1μm. The reason is that as the film thickness increases, the temperature of the film surface decreases, which reduces the surface chemical energy of the atoms, causing the grains to tend to grow in a columnar shape in the (015) direction, reducing the conductivity of the thick film and the dimensionless thermoelectric figure of merit (ZT) value. Summary of the invention

[0005] The present invention is to solve all or part of the problems of the above-mentioned prior art, and provides a method for realizing directional and controllable growth of n-type bismuth telluride thermoelectric thick film (00l) by using step-by-step temperature increase combined with step-by-step in-situ annealing and applying bias voltage to the substrate, which greatly improves the material performance and makes the ZT value greater than 1.1. To achieve the above-mentioned purpose, the technical solution of the present invention is implemented as follows:

[0006] A first aspect of an embodiment of the present invention provides a method for preparing an n-type bismuth telluride thermoelectric thick film, comprising:

[0007] obtaining an aluminum nitride substrate;

[0008] Presetting magnetron sputtering parameters; performing the magnetron sputtering process on the aluminum nitride substrate using a bismuth telluride target and a tellurium target according to the magnetron sputtering parameters to obtain a first thermoelectric thick film;

[0009] The first thermoelectric thick film is subjected to a stepwise temperature raising process to obtain the n-type bismuth telluride thermoelectric thick film.

[0010] Based on the above method, the method further includes that the magnetron sputtering parameters include at least one of the following:

[0011] Bismuth telluride target sputtering power;

[0012] Tellurium target sputtering power;

[0013] Substrate preset temperature;

[0014] The final temperature of the substrate; wherein the final temperature of the substrate is greater than the preset temperature of the substrate;

[0015] Pre-sputtering time;

[0016] Sputtering operation time;

[0017] Sputtering gas pressure;

[0018] Sputtering bias;

[0019] According to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering treatment using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film, and further comprising:

[0020] Pre-sputtering the bismuth telluride target and the tellurium target according to the pre-sputtering time;

[0021] After the pre-sputtering is completed, a DC power supply is applied to the bismuth telluride target according to the sputtering power of the bismuth telluride target and the sputtering power of the telluride target; a radio frequency power supply is applied to the telluride target; an initial temperature of the aluminum nitride substrate is set according to the preset temperature of the substrate; the sputtering gas pressure is set; and a bias voltage is applied to the aluminum nitride substrate according to the sputtering bias voltage;

[0022] Performing the magnetron sputtering treatment on the aluminum nitride substrate using the bismuth telluride target and the tellurium target;

[0023] If the magnetron sputtering processing time meets the sputtering operation time, the magnetron sputtering processing is stopped to obtain a first thermoelectric thick film;

[0024] determining a target thermoelectric thick film according to the first thermoelectric thick film;

[0025] The first thermoelectric thick film is subjected to a stepwise temperature raising process to obtain the n-type bismuth telluride thermoelectric thick film, further comprising:

[0026] Acquire the aluminum nitride substrate temperature; increase the aluminum nitride substrate temperature by a first preset elevated temperature to obtain an actual substrate temperature, and perform in-situ annealing on the target thermoelectric thick film according to the sputtering operation time; perform magnetron sputtering on the target thermoelectric thick film according to the actual substrate temperature to obtain a current thermoelectric thick film; compare the actual substrate temperature with the preset final temperature; repeat this step until the actual substrate temperature is the same as the preset final temperature;

[0027] It is determined that the current thermoelectric thick film is the n-type bismuth telluride thermoelectric thick film.

[0028] In this way, the temperature of the thick film surface can be maintained stable through step-by-step heating; step-by-step in-situ annealing helps the lateral growth of grains and the layered growth of the thick film along the (001) direction; applying a bias voltage to the substrate can adjust the speed at which particles reach the surface of the thick film, and can also change the surface direction of the particles reaching the thick film through an electric field, thereby reducing the growth speed of the thick film and changing the incident direction of the particles reaching the surface of the thick film, which helps to achieve directional and controllable growth of the thick film in the (001) direction.

[0029] A second aspect of the embodiments of the present disclosure provides an n-type bismuth telluride thermoelectric thick film preparation device, comprising:

[0030] An acquisition module, used for acquiring an aluminum nitride substrate;

[0031] A first processing module is used to preset magnetron sputtering parameters; according to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering process using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film;

[0032] The second processing module is used to perform a step-by-step temperature increase process on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film.

[0033] Based on the above device, the device also includes that the magnetron sputtering parameters include at least one of the following:

[0034] Bismuth telluride target sputtering power;

[0035] Tellurium target sputtering power;

[0036] Substrate preset temperature;

[0037] The final temperature of the substrate; wherein the final temperature of the substrate is greater than the preset temperature of the substrate;

[0038] Pre-sputtering time;

[0039] Sputtering operation time;

[0040] Sputtering gas pressure;

[0041] Sputtering bias;

[0042] The first processing module is used to perform the magnetron sputtering process on the aluminum nitride substrate using a bismuth telluride target and a tellurium target according to the magnetron sputtering parameters to obtain a first thermoelectric thick film, and also includes:

[0043] Pre-sputtering the bismuth telluride target and the tellurium target according to the pre-sputtering time;

[0044] After the pre-sputtering is completed, a DC power supply is applied to the bismuth telluride target according to the sputtering power of the bismuth telluride target and the sputtering power of the telluride target; a radio frequency power supply is applied to the telluride target; an initial temperature of the aluminum nitride substrate is set according to the preset temperature of the substrate; a sputtering gas pressure is set; and a bias voltage is applied to the aluminum nitride substrate according to the sputtering bias voltage;

[0045] Performing the magnetron sputtering treatment on the aluminum nitride substrate using the bismuth telluride target and the tellurium target;

[0046] If the magnetron sputtering processing time meets the sputtering operation time, the magnetron sputtering processing is stopped to obtain a first thermoelectric thick film;

[0047] The second processing module is used to perform a step-by-step temperature increase process on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film, and further includes:

[0048] determining a target thermoelectric thick film according to the first thermoelectric thick film;

[0049] Acquire the aluminum nitride substrate temperature; increase the aluminum nitride substrate temperature by a first preset elevated temperature to obtain an actual substrate temperature, and perform in-situ annealing on the target thermoelectric thick film according to the sputtering operation time; perform magnetron sputtering on the target thermoelectric thick film according to the actual substrate temperature to obtain a current thermoelectric thick film; compare the actual substrate temperature with the preset final temperature; repeat this step until the actual substrate temperature is the same as the preset final temperature;

[0050] It is determined that the current thermoelectric thick film is the n-type bismuth telluride thermoelectric thick film.

[0051] Compared with the prior art, the main beneficial effects of the present invention are as follows: the thickness of the thermoelectric arm in the thermoelectric device can be reduced by the magnetron sputtering method, meeting the requirements of miniaturization and high integration of the thermoelectric device; the present invention adopts a step-by-step temperature increase to keep the temperature of the thick film surface stable; the step-by-step in-situ annealing is helpful for the lateral growth of the grains and the layered growth of the thick film along the (001) direction; the bias voltage applied to the substrate can adjust the speed at which the particles reach the surface of the thick film, and the surface direction of the particles reaching the thick film can also be changed by the electric field, thereby appropriately reducing the growth speed of the thick film, changing the incident direction of the particles reaching the surface of the thick film, and helping to achieve the directional and controllable growth of the thick film in the (001) direction. The thermoelectric figure of merit of the thermoelectric thick film is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A flow chart of a method for preparing an n-type bismuth telluride thermoelectric thick film provided by the present invention;

[0053] Figure 2 A rendering of a method for preparing an n-type bismuth telluride thermoelectric thick film provided by an embodiment of the present invention;

[0054] Figure 3 A test curve of an n-type bismuth telluride thermoelectric thick film after preparation provided by an embodiment of the present invention;

[0055] Figure 4 A schematic diagram of a device for preparing an n-type bismuth telluride thermoelectric thick film provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to enable a more detailed understanding of the features and technical contents of the present application, the implementation of the present application is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the present application.

[0057] like Figure 1 As shown, the present invention provides a method for preparing an n-type bismuth telluride thermoelectric thick film, the method comprising:

[0058] S110: Obtaining an aluminum nitride substrate;

[0059] S120: Preset magnetron sputtering parameters; perform the magnetron sputtering process on the aluminum nitride substrate using a bismuth telluride target and a bismuth target according to the magnetron sputtering parameters to obtain a first thermoelectric thick film;

[0060] S130: performing a step-wise temperature raising process on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film.

[0061] The aluminum nitride is an inorganic non-metallic material synthesized by carbon thermal reduction of aluminum oxide or by nitridation of aluminum. The aluminum nitride has high chemical compatibility as a substrate and can significantly reduce the defect density in the device, thereby improving the performance and service life of the device.

[0062] The magnetron sputtering is a thin film deposition technology. Under the action of the electric field, the electrons collide with argon atoms in the process of flying to the substrate, ionizing them to produce positive argon ions and new electrons; the new electrons fly to the substrate, and the argon ions are accelerated to fly to the cathode target under the action of the electric field, and bombard the target surface with high energy, causing the target material to sputter. Among the sputtered particles, neutral target atoms or molecules are deposited on the substrate to form a thin film, and the secondary electrons generated are affected by the electric field and magnetic field, resulting in drift, and their motion trajectory is similar to a cycloid. If it is a circular magnetic field, the electrons will move in a circular motion on the target surface in an approximate cycloid form. Their motion path is not only very long, but also bound in the plasma region close to the target surface, and a large amount of argon is ionized in this region to bombard the target material, thereby achieving a high deposition rate. As the number of collisions increases, the energy of the secondary electrons is exhausted, gradually moving away from the target surface, and finally deposited on the substrate under the action of the electric field. Since the energy of the electron is very low, the energy transferred to the substrate is very small, resulting in a low temperature rise of the substrate. In the present invention, the substrate is an aluminum nitride substrate, and the target material is a bismuth telluride target and a bismuth target.

[0063] Step-by-step temperature treatment refers to a method of increasing the temperature by the same value in the positive direction of the temperature increase. In the present invention, in the process of preparing a thick film, when the substrate temperature reaches a certain value, the temperature of the film generated by deposition on the substrate surface is lower than the substrate temperature, and continuous temperature increase is likely to cause the indefinite uncontrollable growth of the film, causing the film to grow in a columnar shape, thereby adopting a step-by-step temperature increase method to achieve directional and controllable growth of the film in the (001) direction; wherein the (001) direction refers to the direction parallel to the crystal plane; the crystal plane is a parallel plane with a certain spatial angle.

[0064] In some embodiments, the S110 may include:

[0065] A 380 μm thick aluminum nitride substrate was used as the substrate, and the substrate was ultrasonically cleaned with acetone, alcohol and deionized water for 15 minutes respectively, and then dried in an oven before use, thereby ensuring the cleanliness of the aluminum nitride surface and improving the quality of the prepared thick film.

[0066] In some embodiments, the S120 may include:

[0067] The magnetron sputtering parameters include at least one of the following:

[0068] Bismuth telluride target sputtering power; wherein, the bismuth telluride target sputtering power refers to the power supply power required by the bismuth telluride target; the power supply can be direct current, alternating current, or radio frequency; the bismuth telluride sputtering power can be a predetermined empirical value or experimental value such as 10, 20 or 30; in the present invention, the bismuth telluride sputtering power is 38W DC.

[0069] Tellurium target sputtering power; wherein, the tellurium target sputtering power refers to the power supply power required by the tellurium target; the power supply can be direct current, alternating current, or radio frequency; the tellurium sputtering power can be a predetermined empirical value or experimental value such as 10, 20 or 30; in the present invention, the bismuth telluride sputtering power is 26W radio frequency.

[0070] The substrate preset temperature; wherein the substrate preset temperature may be a predetermined empirical value or experimental value such as 100, 200 or 300; in the present invention, the substrate preset temperature is 400°C.

[0071] The final temperature of the substrate; wherein the final temperature of the substrate is greater than the preset temperature of the substrate; the final temperature of the substrate may be a predetermined empirical value or experimental value such as 100, 200 or 300°C; in the present invention, the final temperature of the substrate is 500°C.

[0072] Pre-sputtering time; wherein, the pre-sputtering refers to removing impurities generated on the surface of the target material due to oxidation, so as to ensure the quality of the film; the pre-sputtering time can be a predetermined empirical value or actual value such as 1, 5 or 10; in the present invention, the pre-sputtering time is 5 minutes.

[0073] Sputtering operation time; wherein, the sputtering operation time refers to the working time of each magnetron sputtering device; the sputtering operation time can be a predetermined empirical value or experimental value such as 10, 20 or 30; in the present invention, the sputtering operation time is 30 minutes.

[0074] Sputtering gas pressure; wherein, the sputtering gas pressure refers to the gas pressure value inside the device when the magnetron sputtering device is working; the sputtering gas pressure can be a predetermined empirical value or experimental value such as 1, 2 or 3; in the present invention, the sputtering gas pressure is 1Pa.

[0075] Sputtering bias; wherein, the sputtering bias refers to the negative voltage applied to the substrate when the magnetron sputtering equipment is working; the sputtering bias can be a predetermined empirical value or experimental value such as 10, 100 or 200; in the present invention, the sputtering bias is 120V.

[0076] According to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering treatment using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film.

[0077] In some embodiments,

[0078] The bismuth telluride target and the tellurium target are pre-sputtered according to the pre-sputtering time; wherein, the pre-sputtering can remove impurities generated on the surface of the target material due to oxidation, thereby ensuring the quality of the prepared thick film.

[0079] After the pre-sputtering is completed, a DC power supply is applied to the bismuth telluride target according to the sputtering power of the bismuth telluride target and the sputtering power of the telluride target; an RF power supply is applied to the telluride target; the initial temperature of the aluminum nitride substrate is set according to the preset temperature of the substrate; the sputtering gas pressure is set; and a bias is applied to the aluminum nitride substrate according to the sputtering bias; wherein, by applying a bias to the aluminum nitride substrate, the speed at which particles reach the surface of the thick film can be adjusted, and the direction in which particles reach the surface of the thick film can also be changed by an electric field. Applying a negative bias to the substrate can appropriately reduce the growth speed of the thick film, change the incident direction of particles reaching the surface of the thick film, and also help to achieve directional and controllable growth of the thick film in the (00l) direction.

[0080] Performing the magnetron sputtering treatment on the aluminum nitride substrate using the bismuth telluride target and the tellurium target;

[0081] If the magnetron sputtering treatment time meets the sputtering operation time, the magnetron sputtering treatment is stopped to obtain a first thermoelectric thick film. In this way, the mobility of the thick film can be greatly improved, thereby improving the thermoelectric figure of merit (ZT) of the material.

[0082] In some embodiments, the S130 may include:

[0083] determining a target thermoelectric thick film according to the first thermoelectric thick film;

[0084] Acquire the temperature of the aluminum nitride substrate; increase the temperature of the aluminum nitride substrate by a first preset elevated temperature to obtain an actual substrate temperature, and perform in-situ annealing on the target thermoelectric thick film according to the sputtering operation time; wherein the in-situ annealing refers to a treatment process in which an object is slowly heated to a certain temperature, maintained in a relative position for a sufficient time, and then cooled at an appropriate speed; for example, if the temperature of the aluminum nitride substrate is 400°C at this time, and the temperature of the film formed on the substrate does not reach 400°C at this time, the temperature of the aluminum nitride substrate is increased by 20°C to 420°C, and the sputtering operation time is maintained so that the temperature of the film formed on the substrate is also maintained at 400°C, and if the film temperature is higher than 400°C, its temperature is cooled to stabilize it. In this way, the lateral growth of the grains is facilitated.

[0085] Performing magnetron sputtering processing on the target thermoelectric thick film according to the actual substrate temperature to obtain a current thermoelectric thick film; comparing the actual substrate temperature with the preset final temperature; repeating this step until the actual substrate temperature is the same as the preset final temperature;

[0086] Determine that the current thermoelectric thick film is the n-type bismuth telluride thermoelectric thick film; in the present invention, the n-type bismuth telluride thermoelectric thick film refers to the n-type ternary phase Bi2Te 2.7 Te 0.3 Hot spot thick film. By increasing the temperature of the sample plate (substrate) in a step-by-step manner, the temperature of the thick film surface can be maintained at a certain level. Step-by-step in-situ annealing also helps the lateral growth of grains. Both contribute to the layered growth of the thick film along the (00l) direction. In addition, the bias voltage can adjust the speed at which particles reach the surface of the thick film, and the direction in which particles reach the surface of the thick film can also be changed through an electric field. Applying a negative bias voltage to the substrate can appropriately reduce the growth rate of the thick film, change the incident direction of particles reaching the surface of the thick film, and also help to achieve directional and controllable growth of the thick film in the (00l) direction.

[0087] In some embodiments,

[0088] The first preset elevated temperature refers to the temperature elevated in the step-by-step temperature elevation process; wherein the first preset elevated temperature may be a predetermined empirical value or experimental value such as 10, 20 or 30 degrees.

[0089] like Figure 2 As shown, an embodiment of the present disclosure provides a rendering of a method for preparing an n-type bismuth telluride thermoelectric thick film;

[0090] In some embodiments,

[0091] A 380 μm thick aluminum nitride substrate was used as the substrate, and the substrate was ultrasonically cleaned with acetone, alcohol and deionized water for 15 minutes respectively, and then dried in an oven before use;

[0092] The cleaned substrate was mounted on the sample plate of the magnetron sputtering equipment (model: FJL005CA) and the target-substrate distance was adjusted to 9 cm. 2.7 Te 0.3 The target (target material: Yongyan, 4N) and Te target (target material: Yongyan, 4N) dual-target co-sputtering method requires 5 minutes of pre-sputtering before the start of sputtering. The specific process parameters of the formal sputtering are Bi2Te 2.7 Te 0.3Target sputtering power: DC 38W, Te target sputtering power: RF 26W, substrate temperature: 400℃, sputtering gas pressure: 1Pa, bias voltage: -120V. After every half hour of sputtering, turn off the sputtering power, increase the substrate temperature by 20℃, maintain the temperature for 30 minutes, then turn on the power and continue sputtering at the original power, repeat this 6 times until the substrate temperature reaches 500℃, and the total sputtering time is 6 hours (excluding the time for substrate heating).

[0093] Increasing the temperature of the sample plate (substrate) in a step-by-step manner can keep the temperature of the thick film surface at a certain level. Step-by-step in-situ annealing also helps the lateral growth of grains. Both contribute to the layered growth of the thick film along the (00l) direction. In addition, the bias voltage can adjust the speed at which particles reach the surface of the thick film, and can also change the direction in which particles reach the surface of the thick film through an electric field. Applying a negative bias voltage to the substrate can appropriately reduce the growth rate of the thick film, change the incident direction of particles reaching the surface of the thick film, and also help to achieve directional and controllable growth of the thick film in the (00l) direction. The n-type ternary phase Bi2Te is realized by step-by-step increasing the substrate temperature, supplemented by step-by-step in-situ annealing, and applying a bias voltage to the substrate at the same time. 2.7 Te 0.3 The thermoelectric thick film has directional controllable growth in the (00l) direction, the material performance is greatly improved, and the thermoelectric figure of merit ZT value is greater than 1.1.

[0094] like Figure 3 As shown, the embodiment of the present disclosure provides a test curve after the preparation of an n-type bismuth telluride thermoelectric thick film;

[0095] In some embodiments,

[0096] Performing thick film characterization test on the prepared n-type bismuth telluride thermoelectric thick film;

[0097] Specifically;

[0098] A scanning electron microscope (model: Sigma 300) was used to photograph the surface and cross-sectional morphology of the thick film and measure the film thickness; a thermoelectric performance comprehensive tester (model: CTA-3S / 1150) was used to measure the Seebeck coefficient and electrical conductivity of the thick film and calculate its power factor; a thin film thermal conductivity tester (model: TFA) was used to test the thermal conductivity of the thick film (the test chip needs to be directly placed on the sample plate of the magnetron sputtering device after being processed); the ZT value of the thick film was obtained by calculation, thereby obtaining a test curve corresponding to the temperature and the ZT value, wherein, through the comparison between the present invention and the prior art, it can be seen that the prepared thick film has a higher ZT value.

[0099] like Figure 4 As shown, the embodiment of the present disclosure provides a device for preparing an n-type bismuth telluride thermoelectric thick film, the device comprising:

[0100] An acquisition module 110 is used to acquire an aluminum nitride substrate;

[0101] A first processing module 120 is used to preset magnetron sputtering parameters; according to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering process using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film;

[0102] The second processing module 130 is used to perform a step-by-step temperature increase process on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film.

[0103] In some embodiments, the acquisition module 110, the first processing module 120 and the second processing module 130 may be program modules; after the program modules are executed by a processor, operations of each module may be implemented.

[0104] In other embodiments, the acquisition module 110, the first processing module 120 and the second processing module 130 may be soft-hard combination modules; the soft-hard combination modules include but are not limited to: various programmable arrays; the programmable arrays include but are not limited to: field programmable arrays and / or complex programmable arrays.

[0105] In some other embodiments, the acquisition module 110, the first processing module 120 and the second processing module 130 may be pure hardware modules; the pure hardware modules include but are not limited to: application specific integrated circuits.

[0106] In some embodiments, the acquisition module 110 may include:

[0107] A 380 μm thick aluminum nitride substrate was used as the substrate, and the substrate was ultrasonically cleaned with acetone, alcohol and deionized water for 15 minutes respectively, and then dried in an oven before use, thereby ensuring the cleanliness of the aluminum nitride surface and improving the quality of the prepared thick film.

[0108] In some embodiments, the first processing module 120 may include:

[0109] The magnetron sputtering parameters include at least one of the following:

[0110] Bismuth telluride target sputtering power; wherein, the bismuth telluride target sputtering power refers to the power supply power required by the bismuth telluride target; the power supply can be direct current, alternating current, or radio frequency; the bismuth telluride sputtering power can be a predetermined empirical value or experimental value such as 10, 20 or 30; in the present invention, the bismuth telluride sputtering power is 38W DC.

[0111] Tellurium target sputtering power; wherein, the tellurium target sputtering power refers to the power supply power required by the tellurium target; the power supply can be direct current, alternating current, or radio frequency; the tellurium sputtering power can be a predetermined empirical value or experimental value such as 10, 20 or 30; in the present invention, the bismuth telluride sputtering power is 26W radio frequency.

[0112] The substrate preset temperature; wherein the substrate preset temperature may be a predetermined empirical value or experimental value such as 100, 200 or 300; in the present invention, the substrate preset temperature is 400°C.

[0113] The final temperature of the substrate; wherein the final temperature of the substrate is greater than the preset temperature of the substrate; the final temperature of the substrate may be a predetermined empirical value or experimental value such as 100, 200 or 300°C; in the present invention, the final temperature of the substrate is 500°C.

[0114] Pre-sputtering time; wherein, the pre-sputtering refers to removing impurities generated on the surface of the target material due to oxidation, so as to ensure the quality of the film; the pre-sputtering time can be a predetermined empirical value or actual value such as 1, 5 or 10; in the present invention, the pre-sputtering time is 5 minutes.

[0115] Sputtering operation time; wherein, the sputtering operation time refers to the working time of each magnetron sputtering device; the sputtering operation time can be a predetermined empirical value or experimental value such as 10, 20 or 30; in the present invention, the sputtering operation time is 30 minutes.

[0116] Sputtering gas pressure; wherein, the sputtering gas pressure refers to the gas pressure value inside the device when the magnetron sputtering device is working; the sputtering gas pressure can be a predetermined empirical value or experimental value such as 1, 2 or 3; in the present invention, the sputtering gas pressure is 1Pa.

[0117] Sputtering bias; wherein, the sputtering bias refers to the negative voltage applied to the substrate when the magnetron sputtering equipment is working; the sputtering bias can be a predetermined empirical value or experimental value such as 10, 100 or 200; in the present invention, the sputtering bias is 120V.

[0118] According to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering treatment using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film.

[0119] In some embodiments,

[0120] The bismuth telluride target and the tellurium target are pre-sputtered according to the pre-sputtering time; wherein, the pre-sputtering can remove impurities generated on the surface of the target material due to oxidation, thereby ensuring the quality of the prepared thick film.

[0121] After the pre-sputtering is completed, a DC power supply is applied to the bismuth telluride target according to the sputtering power of the bismuth telluride target and the sputtering power of the telluride target; an RF power supply is applied to the telluride target; the initial temperature of the aluminum nitride substrate is set according to the preset temperature of the substrate; the sputtering gas pressure is set; and a bias is applied to the aluminum nitride substrate according to the sputtering bias; wherein, by applying a bias to the aluminum nitride substrate, the speed at which particles reach the surface of the thick film can be adjusted, and the direction in which particles reach the surface of the thick film can also be changed by an electric field. Applying a negative bias to the substrate can appropriately reduce the growth speed of the thick film, change the incident direction of particles reaching the surface of the thick film, and also help to achieve directional and controllable growth of the thick film in the (00l) direction.

[0122] Performing the magnetron sputtering treatment on the aluminum nitride substrate using the bismuth telluride target and the tellurium target;

[0123] If the magnetron sputtering treatment time meets the sputtering operation time, the magnetron sputtering treatment is stopped to obtain a first thermoelectric thick film. In this way, the mobility of the film can be greatly improved, thereby improving the thermoelectric figure of merit (ZT) of the material.

[0124] In some embodiments, the second processing module 130 may include:

[0125] determining a target thermoelectric thick film according to the first thermoelectric thick film;

[0126] Acquire the temperature of the aluminum nitride substrate; increase the temperature of the aluminum nitride substrate by a first preset elevated temperature to obtain an actual substrate temperature, and perform in-situ annealing on the target thermoelectric thick film according to the sputtering operation time; wherein the in-situ annealing refers to a treatment process in which an object is slowly heated to a certain temperature, maintained in a relative position for a sufficient time, and then cooled at an appropriate speed; for example, if the temperature of the aluminum nitride substrate is 400°C at this time, and the temperature of the film formed on the substrate does not reach 400°C at this time, the temperature of the aluminum nitride substrate is increased by 20°C to 420°C, and the sputtering operation time is maintained so that the temperature of the film formed on the substrate is also maintained at 400°C, and if the film temperature is higher than 400°C, its temperature is cooled to stabilize it. In this way, the lateral growth of the grains is facilitated.

[0127] Performing magnetron sputtering processing on the target thermoelectric thick film according to the actual substrate temperature to obtain a current thermoelectric thick film; comparing the actual substrate temperature with the preset final temperature; repeating this step until the actual substrate temperature is the same as the preset final temperature;

[0128] Determine that the current thermoelectric thick film is the n-type bismuth telluride thermoelectric thick film; in the present invention, the n-type bismuth telluride thermoelectric thick film refers to the n-type ternary phase Bi2Te 2.7 Te0.3 Hot spot thick film. By increasing the temperature of the sample plate (substrate) in a step-by-step manner, the temperature of the thick film surface can be maintained at a certain level. Step-by-step in-situ annealing also helps the lateral growth of grains. Both contribute to the layered growth of the thick film along the (00l) direction. In addition, the bias voltage can adjust the speed at which particles reach the surface of the thick film, and the direction in which particles reach the surface of the thick film can also be changed through an electric field. Applying a negative bias voltage to the substrate can appropriately reduce the growth rate of the thick film, change the incident direction of particles reaching the surface of the thick film, and also help to achieve directional and controllable growth of the thick film in the (00l) direction.

[0129] In some embodiments,

[0130] The first preset elevated temperature refers to the temperature elevated in the step-by-step temperature elevation process; wherein the first preset elevated temperature may be a predetermined empirical value or experimental value such as 10, 20 or 30 degrees.

[0131] It should be understood that in the several embodiments provided in the present application, the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0132] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing an n-type bismuth telluride thermoelectric thick film, characterized in that: include; obtaining an aluminum nitride substrate; Presetting magnetron sputtering parameters; performing the magnetron sputtering process on the aluminum nitride substrate using a bismuth telluride target and a tellurium target according to the magnetron sputtering parameters to obtain a first thermoelectric thick film; The first thermoelectric thick film is subjected to a stepwise temperature raising process to obtain the n-type bismuth telluride thermoelectric thick film.

2. The method for preparing a thermoelectric thick film according to claim 1, characterized in that: The magnetron sputtering parameters include at least one of the following: Bismuth telluride target sputtering power; Tellurium target sputtering power; Substrate preset temperature; The final temperature of the substrate; wherein the final temperature of the substrate is greater than the preset temperature of the substrate; Pre-sputtering time; Sputtering operation time; Sputtering gas pressure; Sputtering bias.

3. The method for preparing a thermoelectric thick film according to claim 2, characterized in that: According to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering treatment using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film, and further comprising: Pre-sputtering the bismuth telluride target and the tellurium target according to the pre-sputtering time; After the pre-sputtering is completed, a DC power supply is applied to the bismuth telluride target according to the sputtering power of the bismuth telluride target and the sputtering power of the telluride target; a radio frequency power supply is applied to the telluride target; an initial temperature of the aluminum nitride substrate is set according to the preset temperature of the substrate; the sputtering gas pressure is set; and a bias voltage is applied to the aluminum nitride substrate according to the sputtering bias voltage; Performing the magnetron sputtering treatment on the aluminum nitride substrate using the bismuth telluride target and the tellurium target; If the magnetron sputtering processing time meets the sputtering operation time, the magnetron sputtering processing is stopped to obtain a first thermoelectric thick film.

4. The method for preparing a thermoelectric thick film according to claim 3, characterized in that: The first thermoelectric thick film is subjected to a stepwise temperature raising process to obtain the n-type bismuth telluride thermoelectric thick film, further comprising: determining a target thermoelectric thick film according to the first thermoelectric thick film; Acquire the aluminum nitride substrate temperature; increase the aluminum nitride substrate temperature by a first preset elevated temperature to obtain an actual substrate temperature, and perform in-situ annealing on the target thermoelectric thick film according to the sputtering operation time; perform magnetron sputtering on the target thermoelectric thick film according to the actual substrate temperature to obtain a current thermoelectric thick film; compare the actual substrate temperature with the preset final temperature; repeat this step until the actual substrate temperature is the same as the preset final temperature; It is determined that the current thermoelectric thick film is the n-type bismuth telluride thermoelectric thick film.

5. An n-type bismuth telluride thermoelectric thick film preparation device, characterized in that: include: An acquisition module, used for acquiring an aluminum nitride substrate; A first processing module, used for presetting magnetron sputtering parameters; According to the magnetron sputtering parameters, the aluminum nitride substrate is subjected to the magnetron sputtering treatment using a bismuth telluride target and a tellurium target to obtain a first thermoelectric thick film; The second processing module is used to perform a step-by-step temperature increase process on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film.

6. The thermoelectric thick film preparation device according to claim 5, characterized in that: The magnetron sputtering parameters include at least one of the following: Bismuth telluride target sputtering power; Tellurium target sputtering power; Substrate preset temperature; The final temperature of the substrate; wherein the final temperature of the substrate is greater than the preset temperature of the substrate; Pre-sputtering time; Sputtering operation time; Sputtering gas pressure; Sputtering bias.

7. The thermoelectric thick film preparation device according to claim 6, characterized in that: The first processing module is used to perform the magnetron sputtering process on the aluminum nitride substrate using a bismuth telluride target and a tellurium target according to the magnetron sputtering parameters to obtain a first thermoelectric thick film, and also includes: Pre-sputtering the bismuth telluride target and the tellurium target according to the pre-sputtering time; After the pre-sputtering is completed, a DC power supply is applied to the bismuth telluride target according to the sputtering power of the bismuth telluride target and the sputtering power of the telluride target; a radio frequency power supply is applied to the telluride target; an initial temperature of the aluminum nitride substrate is set according to the preset temperature of the substrate; a sputtering gas pressure is set; and a bias voltage is applied to the aluminum nitride substrate according to the sputtering bias voltage; Performing the magnetron sputtering treatment on the aluminum nitride substrate using the bismuth telluride target and the tellurium target; If the magnetron sputtering processing time meets the sputtering operation time, the magnetron sputtering processing is stopped to obtain a first thermoelectric thick film.

8. The thermoelectric thick film preparation device according to claim 7, characterized in that: The second processing module is used to perform a step-by-step temperature increase process on the first thermoelectric thick film to obtain the n-type bismuth telluride thermoelectric thick film, and further includes: determining a target thermoelectric thick film according to the first thermoelectric thick film; Acquire the aluminum nitride substrate temperature; raise the aluminum nitride substrate temperature by a first preset elevated temperature to obtain an actual substrate temperature, and perform in-situ annealing on the target thermoelectric thick film according to the sputtering operation time; perform magnetron sputtering on the target thermoelectric thick film according to the actual substrate temperature to obtain a current thermoelectric thick film; compare the actual substrate temperature with the preset final temperature; repeat this step until the actual substrate temperature is the same as the preset final temperature; It is determined that the current thermoelectric thick film is the n-type bismuth telluride thermoelectric thick film.

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