Preparation method of PdSe2 film on Ge

Abstract

The invention relates to a method for preparing a PdSe2 film on Ge, which comprises the following steps of: firstly, carrying out oxygen plasma treatment on a Ge sheet, forming a GeO2 thin layer on the surface of the Ge sheet, and preventing Ge and Se from reacting at high temperature to form GeSex and destroying the continuous reaction of Pd and Se; and then depositing a Pd thin film on the processed Ge sheet by adopting a high vacuum magnetron sputtering technology, and then carrying out selenylation reaction to generate a PdSe2 thin film. The method not only is simple in preparation, but also can improve the performance of the prepared device.

Description

Technical Field

[0001] The invention relates to the field of materials, and in particular to a method for preparing a PdSe2 film on Ge. Background Art

[0002] Graphene is the first two-dimensional material discovered, which can achieve broadband absorption from ultraviolet to far infrared. However, due to the low light absorption characteristics of single-layer or multi-layer graphene, this limits its responsivity in photodetectors. In recent years, researchers have turned their attention to transition metal sulfides (TMDs) with wide bandgap changes and excellent chemical stability. However, the absorption spectra of most transition metal sulfides, such as MoS2 and SnSe2, are limited to visible light.

[0003] The transition metal sulfide palladium diselenide (PdSe2) based on precious metals has an adjustable band gap from 1.3 eV for a monolayer to 0 eV for a bulk, which has attracted much attention in the field of broadband photodetectors. Studies have shown that PdSe2 can not only extend the absorption band of the device to the near infrared, but even to the mid-infrared, providing a new idea for the development of Ge-based broadband infrared detectors.

[0004] Wet transfer device preparation is a preparation method that transfers thin films or other materials from one substrate to another. Although wet transfer has unique advantages in flexibility and material compatibility, such as the ability to prepare materials on different types of substrates, it also has some disadvantages: (1) Damage to crystal quality: Lattice defects may be introduced during the transfer process, such as lattice dislocation and changes in crystal morphology, thereby reducing the performance of the device.

[0005] (2) Interface problems: The interface during the transfer process may not be perfect, which may lead to interface defects and obstruction of electron transfer, resulting in degradation of device performance.

[0006] (3) Mechanical stress: During the transfer process, the film may be affected by mechanical stress, resulting in material damage or deformation, thereby reducing the performance of the device.

[0007] (4) Device consistency: There may be performance differences between different devices, and various factors in the transfer process may lead to inconsistent device performance.

[0008] Currently, the method of integrating PdSe2 thin films on Ge is to transfer PdSe2 selenized on SiO2 to Ge. Although this method can realize the transfer of prefabricated thin films, its preparation process is relatively complicated, and the transfer process can easily cause PdSe2 to wrinkle and crack, resulting in poor contact between PdSe2 and Ge, which greatly affects the performance of the device. Summary of the invention

[0009] The object of the present invention is to provide a method for preparing a PdSe2 thin film on Ge, which method is not only simple to prepare but also can improve the performance of the prepared device.

[0010] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present invention is: a method for preparing a PdSe2 thin film on Ge, firstly treating the Ge sheet with oxygen plasma to form a GeO2 thin layer on the surface of the Ge sheet, thereby preventing Ge and Se from reacting at high temperature to form GeSe x , destroying the continuous reaction between Pd and Se; then a Pd film is deposited on the treated Ge wafer using high vacuum magnetron sputtering technology, and then a selenization reaction is carried out to generate a PdSe2 film.

[0011] Furthermore, the method specifically comprises the following steps: (1) Use a wafer dicing machine to cut the Ge wafer into square wafers of a set size; (2) Place the sliced ​​Ge slices in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for a set time, then soak them in HF solution for a set time, and then rinse them with deionized water. After rinsing, spin dry them with a glue machine; (3) Use a plasma degumming machine to treat the surface of the Ge wafer with oxygen plasma to form a thin layer of GeO2 on the surface of the Ge wafer; (4) Sputtering a Pd film on the Ge wafer treated with oxygen plasma using a high vacuum magnetron sputtering deposition system; (5) Place the Ge sheet sputtered with Pd film and Se powder into a double-temperature zone tubular furnace for reaction; (6) After the tube furnace cools down to room temperature, take out the sample and perform Raman and XRD characterization analysis on the thin film sample prepared on the Ge wafer.

[0012] Furthermore, in step (1), the Ge sheet is cut into square sheets of 1 cm×1 cm in size, the Ge sheet is N-type, has a thickness of 100-400 μm, and a resistivity of 0.01-10 ohm.cm.

[0013] Furthermore, in step (2), the sliced ​​Ge slice is sequentially placed in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 10 minutes, and then immersed in HF solution for 4 minutes.

[0014] Furthermore, in step (3), the conditions for oxygen plasma treatment are: gas pressure 20 Pa, power 40 W, and treatment time 30 min.

[0015] Furthermore, in step (4), the sputtering conditions are: room temperature, power 40 W, gas pressure 0.7 Pa, sputtering 90 s; sputtering forms a 10 nm Pd film.

[0016] Furthermore, in step (5), the dual-temperature zone tubular furnace adopts dual-temperature zone heating growth, the first temperature zone is placed with solid raw material Se powder with a purity higher than 99.999%, the second temperature zone is placed with Ge sheet sputtered with Pd film, the first temperature zone is heated to 350-450°C at a set heating rate, the Se vapor obtained by heating is transported to the second temperature zone by inert gas Ar gas, and then the second temperature zone is heated to 400-450°C at a set heating rate, and the insulation time is 4 h.

[0017] Furthermore, the heating rate of the first temperature zone and the second temperature zone is 10° C. per minute.

[0018] Furthermore, the tail gas treatment device used in the dual-temperature zone tubular furnace is a glass flask with a sodium hydroxide solution.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a PdSe2 thin film on Ge, which realizes in-situ growth of a PdSe2 thin film on Ge by using oxygen plasma treatment and a heat-assisted conversion method, and prevents Ge from reacting with Se at high temperature to form GeSe by introducing a GeO2 thin oxide layer as an intermediate barrier layer. x , destroying the continuous reaction between Pd and Se, and successfully realizing the preparation of PdSe2 thin film on Ge. Compared with wet transfer, this method uses in-situ growth to obtain a more compact and uniform heterojunction interface quality, and the consistency and repeatability of device preparation are high. Not only is the preparation process simple, but it also greatly improves the performance of the prepared device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of sputtering Pd after oxygen treatment of Ge wafer in an embodiment of the present invention; Figure 2 is the Raman spectrum of the Ge / GeO2 / Pd sample under different selenization conditions in the embodiment of the present invention; Figure 3 It is the xrd test diagram of Ge / GeO2 / PdSe2 in the embodiment of the present invention; Figure 4 This is a Raman test diagram of Ge / GeO2 / PdSe2 in an embodiment of the present invention.

[0021] In the figure: 101 - Ge sheet; 102 - GeO2 thin layer; 103 - Pd thin film. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] This embodiment provides a method for preparing a PdSe2 thin film on Ge. First, the Ge wafer is treated with oxygen plasma to form a GeO2 thin layer on the surface of the Ge wafer to prevent Ge and Se from reacting at high temperature to form GeSe. x , destroying the continuous reaction between Pd and Se; then a Pd film is deposited on the treated Ge wafer using high vacuum magnetron sputtering technology, and then a selenization reaction is carried out to generate a PdSe2 film.

[0026] Among them, GeO2 exists as a barrier layer and does not react with Se. GeO2 separates the sputtered Pd and Ge substrate, because Se can react with both Ge and Pd. When Se reacts with Ge, it is difficult to react with Pd to generate PdSe2 signals. In order to prepare PdSe2 thin films on Ge substrates (using xrd and Raman to detect PdSe2 thin film signals), Ge and sputtered Pd need to be separated separately. Oxygen plasma treatment is used on germanium wafers to generate a thin GeO2 layer (the sputtered Pd cannot prevent Se from penetrating), so that Se will not penetrate into the Ge substrate (Se powder falls from top to bottom to the sample surface), but will only stay on the surface of the oxide layer and will only react with the sputtered Pd.

[0027] In this embodiment, the method specifically includes the following steps: (1) Use a wafer dicing machine to cut the purchased commercial Ge wafers into square pieces of 1 cm × 1 cm in size.

[0028] In this embodiment, the Ge sheet is N-type, with a thickness of 100-400 μm and a resistivity of 0.01-10 ohm.cm.

[0029] (2) Place the Ge slices cut into 1 cm × 1 cm sizes in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 10 min respectively, then soak them in HF solution for 4 min, and then rinse them with deionized water. After rinsing, spin dry the Ge slices with a glue spreader to obtain a Ge substrate.

[0030] (3) Use a plasma degumming machine to treat the surface of the Ge wafer with oxygen plasma to form a thin layer of GeO2 on the surface of the Ge wafer.

[0031] In this embodiment, the conditions of oxygen plasma treatment are: gas pressure 20 Pa, power 40 W, and treatment time 30 min.

[0032] (4) A Pd film is sputtered on the Ge wafer after oxygen plasma treatment using a high vacuum magnetron sputtering deposition system.

[0033] In this embodiment, the target material used by the high vacuum magnetron sputtering deposition system to sputter the Pd film is the target material of Zhongnuo New Materials (purity is 99.99%). The sputtering conditions are: room temperature, power 40 W, gas pressure 0.7 Pa, sputtering 90 s. Sputtering forms a Pd film with a thickness of about 10 nm.

[0034] (5) Place the Ge sheet sputtered with Pd film and Se powder into a double-temperature zone tubular furnace for reaction.

[0035] In this embodiment, the Ge sheet sputtered with Pd film is placed on a quartz sheet of 5 cm×7 cm in size and 0.2 mm in thickness, and about 1.2 g of solid raw material Se powder with a purity higher than 99.999% is weighed and placed on the quartz sheet with a groove, and then the quartz sheet with the sample and the quartz groove with Se powder are placed together in a double temperature zone tubular furnace for reaction. Among them, Se powder is placed in the first temperature zone, and the sample to be selenized, that is, the Ge sheet sputtered with Pd film, is placed in the second temperature zone. The first temperature zone is heated to 350 ~ 450 ℃ at a rate of 10 ℃ per minute, and the Se vapor obtained by heating is transported to the second temperature zone by inert gas Ar gas, and then the second temperature zone is heated to 400 ~ 450 ℃ at a rate of 10 ℃ per minute, and the heat preservation time is 4h, and the Ar gas flow rate is 100 sccm. After natural cooling, PdSe2 film is successfully prepared on Ge.

[0036] The tail gas treatment device used in the double-temperature zone tubular furnace for selenization experiments is a glass flask with sodium hydroxide solution.

[0037] (6) After the tube furnace naturally cools down to room temperature, take out the sample, and the PdSe2 thin film is successfully prepared on Ge. Then Raman and XRD characterization analysis are performed on the thin film sample prepared on the Ge wafer.

[0038] Figure 1 Schematic diagram of oxygen-treated Ge wafer followed by sputtering of Pd. Figure 1As shown, firstly, the surface of the Ge substrate 101 is treated with oxygen plasma using a plasma stripper to generate a thin layer of GeO2 102, and then a Pd film 103 with a thickness of about 10 nm is deposited on the Ge / GeO2 using a high vacuum magnetron sputtering deposition system.

[0039] Figure 2 The Raman spectra of the Ge / GeO2 / Pd sample in this embodiment under different selenization conditions are shown in Figure 2. Figure 2 As shown in the figure, a 145 cm -1 , 223 cm -1 、208 cm -1 、258cm -1 The four wavenumber positions correspond to the in-plane B 1g and outer surface A g 1 , A g 2 , A g 3 Active vibration mode, indicating the successful formation of PdSe2 on Ge.

[0040] Figure 3 This is the xrd test pattern of Ge / GeO2 / PdSe2 in this embodiment, position 22.1 。 It is the 002 crystal orientation of PdSe2, proving that PdSe2 is successfully generated on Ge.

[0041] Figure 4 This is the XRD test image of Ge / GeO2 / PdSe2 in this embodiment, Raman spectrum 145 cm -1 , 223 cm -1 、208cm -1 、258 cm -1 The wavenumber positions correspond to the in-plane B 1g and outer surface A g 1 , A g 2 , A g 3 Active vibration mode.

[0042] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a PdSe2 thin film on Ge, characterized in that: First, the Ge wafer is treated with oxygen plasma to form a thin GeO2 layer on the surface of the Ge wafer to prevent Ge and Se from reacting at high temperature to form GeSe. x , destroying the continuous reaction between Pd and Se; then a Pd film is deposited on the treated Ge wafer using high vacuum magnetron sputtering technology, and then a selenization reaction is carried out to generate a PdSe2 film.

2. The method for preparing a PdSe2 thin film on Ge according to claim 1, characterized in that: The specific steps include: (1) Use a wafer dicing machine to cut the Ge wafer into square wafers of a set size; (2) Place the sliced ​​Ge slices in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for a set time, then soak them in HF solution for a set time, and then rinse them with deionized water. After rinsing, spin dry them with a glue machine; (3) Use a plasma degumming machine to treat the surface of the Ge wafer with oxygen plasma to form a thin layer of GeO2 on the surface of the Ge wafer; (4) Sputtering a Pd film on the Ge wafer treated with oxygen plasma using a high vacuum magnetron sputtering deposition system; (5) Place the Ge sheet sputtered with Pd film and Se powder into a double-temperature zone tubular furnace for reaction; (6) After the tube furnace cools down to room temperature, take out the sample and perform Raman and XRD characterization analysis on the thin film sample prepared on the Ge wafer.

3. The method for preparing a PdSe2 thin film on Ge according to claim 2, characterized in that: In step (1), the Ge sheet is cut into square sheets of 1 cm×1 cm in size. The Ge sheet is N-type, with a thickness of 100~400 μm and a resistivity of 0.01~10 ohm.cm.

4. The method for preparing a PdSe2 thin film on Ge according to claim 2, characterized in that: In step (2), the sliced ​​Ge slice is placed in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 10 minutes respectively, and then immersed in HF solution for 4 minutes.

5. The method for preparing a PdSe2 thin film on Ge according to claim 2, characterized in that: In step (3), the conditions for oxygen plasma treatment are: gas pressure 20 Pa, power 40 W, and treatment time 30 min.

6. The method for preparing a PdSe2 thin film on Ge according to claim 2, characterized in that: In step (4), the sputtering conditions are: room temperature, power 40 W, gas pressure 0.7 Pa, and sputtering 90 s; a 10 nm Pd film is formed by sputtering.

7. The method for preparing a PdSe2 thin film on Ge according to claim 2, characterized in that: In step (5), the dual-temperature zone tubular furnace adopts dual-temperature zone heating growth, the first temperature zone is placed with solid raw material Se powder with a purity higher than 99.999%, the second temperature zone is placed with Ge sheet sputtered with Pd film, the first temperature zone is heated to 350-450°C at a set heating rate, the Se vapor obtained by heating is transported to the second temperature zone by inert gas Ar, and then the second temperature zone is heated to 400-450°C at a set heating rate, and the insulation time is 4 h.

8. The method for preparing a PdSe2 thin film on Ge according to claim 7, characterized in that: The heating rate of the first temperature zone and the second temperature zone is 10° C. per minute.

9. The method for preparing a PdSe2 thin film on Ge according to claim 2, characterized in that: The tail gas treatment device used in the dual-temperature zone tubular furnace is a glass flask with a sodium hydroxide solution.

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