Preparation method of Bi4Se3 + BiSe mixed-phase semiconductor thermoelectric thin film

Abstract

The invention discloses a preparation method of a Bi4Se3 + BiSe mixed phase semiconductor thermoelectric film, and relates to a preparation method of a semiconductor thermoelectric film. The method sequentially comprises the following preparation processes: 1, determination of a deposition technology; 2, preparing a target material and determining components of the target material; 3, selection and pretreatment of a substrate; 4, determining a deposition process; 5, determining the heating mode and temperature of the substrate; and 6, determining the rotation speed of the substrate. According to the method for preparing the magnetron sputtering Bi-Se semiconductor thermoelectric thin film by adopting the single Bi2Se2.6 target, the Bi4Se3 + BiSe mixed phase semiconductor thermoelectric thin film can be obtained, collaborative regulation and control of thin film phase composition and thermoelectric performance are achieved, the preparation cost is low, operation is easy, and good stability and repeatability are achieved.

Description

Technical Field

[0001] The present invention relates to a method for preparing a semiconductor thermoelectric thin film, in particular to a method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film. Background Art

[0002] Among the existing near-room-temperature thermoelectric material systems, Bi-Te thermoelectric thin films have been commercialized, but the core element Te has low abundance in the earth's crust and is expensive. m (Bi2Se3) n Homologous compounds have become competitive new alternative materials and have received widespread attention. These materials have shown potential for thermoelectric applications in terms of electronic band structure, optical response and mechanical properties.

[0003] A variety of deposition techniques are used in the research and application of Bi-Te, Bi-Se, and other thermoelectric thin film material systems, including molecular beam epitaxy, thermal evaporation, chemical vapor deposition, pulsed laser deposition, and magnetron sputtering. Among these techniques, magnetron sputtering offers advantages such as low cost, high stability, good reproducibility, and easy composition control, making it more suitable for the preparation of high-quality, high-purity Bi-Te, Bi-Se, and other semiconductor thermoelectric thin films.

[0004] However, existing technologies and research have primarily focused on developing Bi-Se thin films with specific ideal chemical compositions (e.g., Bi2Se3 or BiSe), or enhancing the film's thermoelectric properties by doping with other elements. To date, there is no method for fabricating and controlling Bi-Se semiconductor thermoelectric thin films that can achieve thermoelectric performance control by manipulating the phase composition of mixed-phase films, thus limiting their application. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a Bi4Se3+BiSe mixed phase semiconductor thermoelectric film. 2.6 The target source prepared a Bi4Se3+BiSe two-phase mixed Bi-Se semiconductor thermoelectric film, which achieved the adjustable and controllable film phase composition and thermoelectric properties. It has low preparation cost, easy operation, good stability and repeatability.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film includes the following steps: 1. Determination of deposition technology: Determine the radio frequency magnetron sputtering deposition system as the preparation technology for Bi4Se3+BiSe mixed phase semiconductor thermoelectric films.

[0007] 2. Target preparation method and target composition determination: High-purity Bi and Se powders are ball-milled and mixed in a certain proportion, and then vacuum hot pressing and sintering are used to prepare Bi2Se with a purity of 99.99%. 2.6 target, and determine the single Bi2Se 2.6 The target is used as the magnetron target source for radio frequency magnetron sputtering technology.

[0008] 3. Substrate Selection and Pretreatment: Commercially polished intrinsic high-resistance single-crystal silicon with a (100) orientation was selected as the substrate material. Before deposition in the coating chamber, the substrate was ultrasonically cleaned for 15 minutes using acetone and then anhydrous ethanol to remove oil and physically adsorbed impurities on the surface. The substrate was then dried with a hair dryer and vacuum-sealed for storage.

[0009] 4. Determination of deposition process: This refers to the deposition process used to prepare Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin films using magnetron sputtering technology. The deposition process is divided into four stages. In the first stage, when the background vacuum of the deposition system reaches 7.0×10 -4 Pa, heat the substrate, and keep the substrate rotation speed at 5 rpm during heating; second, when the set temperature is reached, introduce argon gas to keep the argon pressure in the coating chamber at 0.6 Pa, keep the substrate baffle closed, and start the Bi2Se 2.6 The target was pre-sputtered for 10 minutes with a sputtering power of 50 watts to complete the target surface self-cleaning process. In the third step, after the pre-sputtering was completed, the substrate shutter was opened, the sputtering power was still maintained at 50 watts, and the substrate temperature remained unchanged. The formal deposition was carried out for 60 minutes. In the fourth step, after the coating stage was completed, the substrate shutter was closed, the heating power supply and the RF power supply were turned off in sequence, and the substrate was continued to rotate for uniform heat dissipation. The substrate was then cooled to room temperature in the vacuum furnace.

[0010] 5. Determination of substrate heating method and temperature: The substrate heating method adopts resistance wire heating. When the substrate is heated, the heating rate is maintained at 15 ℃ / minute, the temperature difference is ±0.1 ℃, and the set temperature range is 350~380 ℃.

[0011] 6. Determination of substrate rotation speed: The substrate is kept rotating at a speed of 5 rpm during the entire process of substrate heating, thin film deposition, and substrate cooling after coating.

[0012] According to the present invention, a single Bi2Se 2.6The method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric film using a target can produce a mixed-phase semiconductor thermoelectric film with a phase composition of Bi4Se3+BiSe. The film is composed of a Bi4Se3+BiSe mixed phase, with a molar ratio of Bi4Se3 to BiSe of 55.5 / 44.5 to 59.5 / 40.5. The film thickness is 1.1±0.1 microns, and the grain size is between 500 and 600 nanometers. The room temperature conductivity of the film is 14.5×10 3 ~15.3×10 3 S·m -1 The room temperature Seebeck coefficient of the film is -93.57~-97.8 μV·K -1 The room temperature power factor of the film is 0.13~0.15mW·cm -1 ·K -2 .

[0013] The significant features and positive effects of the present invention are: The present invention determines the conventional radio frequency magnetron sputtering deposition system as the preparation technology for preparing Bi4Se3+BiSe mixed phase semiconductor thermoelectric thin films, and determines the vacuum hot pressing sintering synthesis of Bi2Se 2.6 The target was used as a single magnetron sputtering target. The heating temperature of the intrinsic single crystal silicon (100) substrate was determined to be 350-380 °C, the RF sputtering power was determined to be 50 watts during the deposition process, and the deposition time was determined to be 60 minutes. This ensured that the phase composition of the prepared film was a Bi4Se3+BiSe mixed phase, and the molar ratio of the Bi4Se3 and BiSe phases was ensured to be 55.5 / 44.5 to 59.5 / 40.5, thereby ensuring that the room temperature conductivity of the film was 14.5×10 3 ~15.3×10 3 S·m -1 , Seebeck coefficient at room temperature is -93.57~ -97.8 μV·K -1 , room temperature power factor is 0.13~0.15 mW·cm -1 ·K -2 and other thermoelectric performance indicators, and finally achieved the dual regulation of the phase composition and performance indicators of Bi-Se semiconductor thermoelectric films. DETAILED DESCRIPTION

[0014] The present invention is described in detail below with reference to the embodiments. Example 1

[0015] A Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film is prepared on commercial single crystal silicon (100), wherein the method is: (1) Determination of deposition technology: Determine the radio frequency magnetron sputtering deposition system as the preparation technology for Bi4Se3+BiSe mixed phase semiconductor thermoelectric thin films.

[0016] (2) Target preparation method and target composition determination: High-purity Bi and Se powders are ball-milled and mixed in a certain proportion, and then Bi2Se with a purity of 99.99% is prepared by vacuum hot pressing and sintering. 2.6 target, and determine the single Bi2Se 2.6 The target is used as the magnetron target source for radio frequency magnetron sputtering technology.

[0017] (3) Substrate selection and pretreatment: Commercially polished intrinsic high-resistance single-crystal silicon was selected as the substrate material, with a crystal orientation of (100). Before being placed in the coating chamber for deposition, the substrate was ultrasonically cleaned for 15 min using acetone and anhydrous ethanol, respectively, to remove oil stains and physically adsorbed impurities on the substrate surface. The substrate was then dried with a hair dryer and vacuum-sealed for storage.

[0018] (4) Determination of deposition process: refers to the deposition process used to prepare Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin films using magnetron sputtering technology. The deposition process is divided into four stages. In the first stage, when the background vacuum of the deposition system reaches 7.0×10 -4 Pa, heat the substrate, and keep the substrate rotation speed at 5 rpm during heating; second, when the set temperature is reached, introduce argon gas to keep the argon pressure in the coating chamber at 0.6 Pa, keep the substrate baffle closed, and start the Bi2Se 2.6 The target was pre-sputtered for 10 minutes with a sputtering power of 50 watts to complete the target surface self-cleaning process. In the third step, after the pre-sputtering was completed, the substrate shutter was opened, the sputtering power was still maintained at 50 watts, and the substrate temperature remained unchanged. The formal deposition was carried out for 60 minutes. In the fourth step, after the coating stage was completed, the substrate shutter was closed, the heating power supply and the RF power supply were turned off in sequence, and the substrate was continued to rotate for uniform heat dissipation. The substrate was then cooled to room temperature in the vacuum furnace.

[0019] (5) Determination of substrate heating method and temperature: The substrate heating method adopts resistance wire heating. When the substrate is heated, the heating rate is maintained at 15 ℃ / min, the temperature difference is ±0.1 ℃, and the substrate heating temperature is set to 350 ℃.

[0020] (6) Determination of substrate rotation speed: The substrate is kept rotating at a speed of 5 rpm during the entire process of substrate heating, thin film deposition, and substrate cooling after coating.

[0021] The thin film prepared by the above method was tested and the results showed that the single Bi2Se 2.6A method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film using a target can produce a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film. The film consists of a Bi4Se3+BiSe mixed phase, with a molar ratio of Bi4Se3 to BiSe of 56 / 44. The film thickness is 1.12 microns, and the grain size is between 500 and 600 nanometers. The room temperature conductivity of the film is 14.5×10 3 S·m -1 The room temperature Seebeck coefficient of the film is -93.57 μV·K -1 The room temperature power factor of the film is 0.13 mW·cm -1 ·K -2 . Example 2

[0022] A Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film is prepared on commercial single crystal silicon (100), wherein the method is: (1) Determination of deposition technology: Determine the radio frequency magnetron sputtering deposition system as the preparation technology for Bi4Se3+BiSe mixed phase semiconductor thermoelectric thin films.

[0023] (2) Target preparation method and target composition determination: High-purity Bi and Se powders are ball-milled and mixed in a certain proportion, and then Bi2Se with a purity of 99.99% is prepared by vacuum hot pressing and sintering. 2.6 target, and determine the single Bi2Se 2.6 The target is used as the magnetron target source for radio frequency magnetron sputtering technology.

[0024] (3) Substrate selection and pretreatment: Commercially polished intrinsic high-resistance single-crystal silicon was selected as the substrate material, with a crystal orientation of (100). Before being placed in the coating chamber for deposition, the substrate was ultrasonically cleaned for 15 min using acetone and anhydrous ethanol, respectively, to remove oil stains and physically adsorbed impurities on the substrate surface. The substrate was then dried with a hair dryer and vacuum-sealed for storage.

[0025] (4) Determination of deposition process: refers to the deposition process used to prepare Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin films using magnetron sputtering technology. The deposition process is divided into four stages. In the first stage, when the background vacuum of the deposition system reaches 7.0×10 -4 Pa, heat the substrate, and keep the substrate rotation speed at 5 rpm during heating; second, when the set temperature is reached, introduce argon gas to keep the argon pressure in the coating chamber at 0.6 Pa, keep the substrate baffle closed, and start the Bi2Se 2.6The target was pre-sputtered for 10 minutes with a sputtering power of 50 watts to complete the target surface self-cleaning process. In the third step, after the pre-sputtering was completed, the substrate shutter was opened, the sputtering power was still maintained at 50 watts, and the substrate temperature remained unchanged. The formal deposition was carried out for 60 minutes. In the fourth step, after the coating stage was completed, the substrate shutter was closed, the heating power supply and the RF power supply were turned off in sequence, and the substrate was continued to rotate for uniform heat dissipation. The substrate was then cooled to room temperature in the vacuum furnace.

[0026] (5) Determination of substrate heating method and temperature: The substrate heating method adopts resistance wire heating. When the substrate is heated, the heating rate is maintained at 15 ℃ / min, the temperature difference is ±0.1 ℃, and the substrate heating temperature is set to 380 ℃.

[0027] (6) Determination of substrate rotation speed: The substrate is kept rotating at a speed of 5 rpm during the entire process of substrate heating, thin film deposition, and substrate cooling after coating.

[0028] The thin film prepared by the above method was tested and the results showed that the single Bi2Se 2.6 A method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film using a target can produce a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film. The film consists of a Bi4Se3+BiSe mixed phase, with a molar ratio of Bi4Se3 to BiSe of 59.5 / 40.5. The film thickness is 1.14 microns, with a grain size of 500 to 600 nanometers. The room-temperature conductivity of the film is 15.3×10 3 S·m -1 The room temperature Seebeck coefficient of the film is -97.8 μV·K -1 The room temperature power factor of the film is 0.15 mW·cm -1 ·K -2 .

Claims

1. A method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film, characterized in that: The preparation process of the method is: (1) Determination of deposition technology: Determine the radio frequency magnetron sputtering deposition system as the preparation of Bi4Se3+BiSe mixed phase semiconductor thermoelectric thin films; (2) Target preparation method and target composition determination: High-purity Bi and Se powders are ball-milled and mixed in proportion, and then Bi2Se with a purity of 99.99% is prepared by vacuum hot pressing and sintering. 2.6 target, and determine the single Bi2Se 2.6 The target is used as the magnetron target source for radio frequency magnetron sputtering technology; (3) Substrate selection and pretreatment: Commercially polished intrinsic high-resistance single-crystal silicon was selected as the substrate material with a crystal orientation of (100). Before being placed in the coating chamber for deposition, the substrate was ultrasonically cleaned for 15 min using acetone and anhydrous ethanol respectively to remove oil stains and physically adsorbed impurities on the substrate surface. The substrate was then dried with a hair dryer and vacuum sealed for storage. (4) Determination of deposition process: refers to the deposition process used to prepare Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin films using magnetron sputtering technology. The deposition process is divided into four stages. In the first stage, when the background vacuum of the deposition system reaches 7.0×10 -4 Pa, heat the substrate, and keep the substrate rotation speed at 5 rpm during heating; second, when the set temperature is reached, introduce argon gas to keep the argon pressure in the coating chamber at 0.6 Pa, keep the substrate baffle closed, and start the Bi2Se 2.6 The target is pre-sputtered for 10 minutes with a sputtering power of 50 watts to complete the self-cleaning treatment of the target surface. In the third step, after the pre-sputtering is completed, the substrate baffle is opened, the sputtering power is still maintained at 50 watts, the substrate temperature remains unchanged, and the formal deposition is carried out for 60 minutes. In the fourth step, after the coating stage is completed, the substrate baffle is closed in sequence, the heating power supply and the RF power supply are turned off, and the substrate rotation is continued to ensure uniform heat dissipation. The substrate is cooled to room temperature in the vacuum state. (5) Determination of substrate heating method and temperature: The substrate heating method adopts resistance wire heating. When the substrate is heated, the heating rate is maintained at 15 ℃ / min, the temperature difference is ±0.1 ℃, and the set temperature range is 350~380 ℃; (6) Determination of substrate rotation speed: The substrate is kept rotating at a speed of 5 rpm during the entire process of substrate heating, thin film deposition, and substrate cooling after coating.

2. The method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film according to claim 1, characterized in that: The molar ratio of the Bi4Se3 and BiSe phases is 55.5 / 44.5 to 59.5 / 40.

5.

3. The method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film according to claim 1, characterized in that: The film thickness is 1.1±0.1 micrometers, and the grain size is between 500 and 600 nanometers.

4. The method for preparing a Bi4Se3+BiSe mixed-phase semiconductor thermoelectric thin film according to claim 1, characterized in that: The room temperature conductivity of the film is 14.5×10 3 ~15.3×10 3 S·m -1 The room temperature Seebeck coefficient of the film is -93.57~-97.8 μV·K -1 The room temperature power factor of the film is 0.13~0.15 mW·cm -1 ·K -2 .