A preparation method of gamma-phase germanium selenide nanosheet

Abstract

The application discloses a preparation method of gamma-phase germanium selenide nanosheets. The application realizes controllable preparation of high-quality gamma-phase germanium selenide nanosheets by adopting a normal-pressure vapor deposition method and based on a rapid cooling strategy. The application realizes controllable growth of gamma-phase germanium selenide nanosheets with different lateral sizes by controlling growth temperature. The application does not need to plate a catalyst such as gold on a substrate surface, and the preparation process is relatively simple. The prepared gamma-phase germanium selenide nanosheets have great application potential in flexible sensors, photoelectric devices, especially near-infrared photoelectric detectors and the like. The gamma-phase germanium selenide nanosheets prepared by the application are still very stable after being placed in air for half a year, and also provide a good experimental platform for subsequent physical property research on the material.

Description

Technical Field

[0001] This invention relates to the preparation of germanium selenide nanomaterials, and particularly to a method for preparing γ-phase germanium selenide nanosheets. Background Technology

[0002] Two-dimensional layered materials have attracted widespread attention due to their excellent physical and chemical properties. The various properties of two-dimensional materials largely depend on the number of layers, interlayer packing, and phase structure. Therefore, exploring different crystal structures of two-dimensional materials is an important research topic in this field. Phase engineering design of two-dimensional materials is crucial for controlling their electrical, chemical, and other physical properties. Therefore, achieving controllable fabrication of phase structures in two-dimensional materials can open up a new path for regulating their various properties.

[0003] Group IV-VI chalcogenides (GeS, GeSe, SnS, SnSe) are a group of two-dimensional layered materials that have attracted much attention in recent years. They typically possess a layered, wrinkled structure similar to black phosphorus, which gives them significant anisotropic properties. Systematic studies have shown that Group IV-VI chalcogenides exhibit excellent ferroelectric, thermoelectric, ferromagnetic, and piezoelectric properties. Germanium selenide, as a typical member of Group IV-VI chalcogenides, exhibits significant optical and electrical anisotropy and has attracted widespread attention due to its potential application in near-infrared polarized photodetectors. Typically, α-phase germanium selenide has been systematically studied as a typical wrinkled layered crystal structure. However, researchers recently predicted the existence of a novel four-atom-thick hexagonal phase in germanium selenide, namely the γ-phase germanium selenide. Currently, most research on γ-phase germanium selenide remains at the theoretical prediction level, and research on the controllable preparation of this material is still in its early stages. Therefore, achieving controllable preparation of high-quality γ-phase germanium selenide, as well as reducing its preparation cost and simplifying its preparation process, is crucial for realizing industrial-scale production. Summary of the Invention

[0004] To address the technical challenge of the lack of controllable preparation of existing γ-phase germanium selenide nanomaterials, this invention provides a method for preparing γ-phase germanium selenide nanosheets. Employing atmospheric pressure vapor deposition and a rapid cooling strategy, high-quality γ-phase germanium selenide nanosheets were controllably prepared. By controlling the growth temperature, the invention achieved the controllable growth of γ-phase germanium selenide nanosheets of different sizes. This method is relatively simple, and the prepared γ-phase germanium selenide nanosheets show great application potential in flexible sensors, optoelectronic devices, and especially near-infrared photodetectors. The prepared γ-phase germanium selenide nanosheets remain highly stable after being exposed to air for six months, providing an excellent experimental platform for subsequent research on the material's properties.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing γ-phase germanium selenide nanosheets includes the following steps:

[0007] (1) First place the substrate on the graphite sheet, and then push the graphite sheet to the downstream of the horizontal tube furnace according to the direction of airflow from upstream to downstream.

[0008] (2) Take germanium selenide powder and put it into a quartz boat, and place the quartz boat at the upstream inlet of the tube furnace;

[0009] (3) Open the gas valve and introduce argon gas into the horizontal tube furnace. Clean the reaction chamber for 30 to 60 minutes before running the equipment.

[0010] (4) Set the heating program, using argon as the carrier gas. When the heating center is heated to the growth temperature of 500℃~600℃, push the quartz boat to the heating center of the tube furnace through the magnetic control device.

[0011] (5) After maintaining the temperature of the center of the heating zone for 9 to 13 minutes, open the furnace cover of the tubular furnace and continue to introduce the carrier gas to cool down the furnace (the temperature drops very quickly) until the temperature inside the tube is cooled to room temperature, thus obtaining γ-phase germanium selenide nanosheets.

[0012] Furthermore, it also includes closing the argon gas valve after the growth process is complete.

[0013] In step (1), the substrate is preferably either a mica substrate or a silicon dioxide substrate; and the distance between the substrate and the heating center of the tube furnace is 8.5cm to 10.5cm.

[0014] Furthermore, in step (2), the amount of germanium selenide powder is 3mg to 5mg, and the germanium selenide powder is high-purity germanium selenide powder with a purity of 99.99%.

[0015] Furthermore, in step (4), the argon flow rate is 3 sccm to 5 sccm.

[0016] Furthermore, the preferred growth temperature is 530℃~570℃.

[0017] Furthermore, the preferred temperature holding time is 10 to 12 minutes.

[0018] Furthermore, in step (5), opening the furnace lid and continuously introducing carrier gas allows the temperature inside the tube to rapidly drop to room temperature. During this rapid cooling process, energy is released dramatically, generating stress that induces the crystalline germanium diselenide film to transform into an amorphous germanium diselenide film. Due to the rapid temperature drop, the precursor still inside the tube begins to form nucleation sites on the surface of the amorphous germanium diselenide film, which is beneficial for the growth of γ-phase germanium selenide.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) This invention employs a vapor deposition method based on a rapid cooling strategy. During the rapid cooling process, the energy in the high-temperature environment inside the tubular furnace is inevitably released rapidly, resulting in stress and causing the crystalline germanium diselenide film to transform into an amorphous germanium diselenide film. The structural incompatibility between the precursor and the amorphous germanium diselenide film leads to imperfect surface nucleation sites, prompting the growth of γ-phase germanium selenide sub-selenide to follow a spiral dislocation growth mode, thus realizing the growth of γ-phase germanium selenide sub-selenide nanosheets.

[0021] (2) This invention does not require the addition of chloride, hydroxide or other related catalysts during the experiment. In the entire experiment, only high-purity germanium selenide powder is used as the only precursor, thus avoiding the introduction of impurity elements.

[0022] (3) The present invention does not require gold plating on the substrate surface or other substrate design strategies, which greatly reduces the preparation cost and simplifies the preparation process.

[0023] (4) By utilizing atmospheric pressure vapor deposition, the present invention requires very little precursor during material growth, a very small carrier gas flow rate during growth, and a low growth temperature, providing an effective and economical experimental method for subsequent industrial production of materials.

[0024] (5) The present invention uses a vapor deposition method, which is different from mechanical exfoliation, hydrothermal method and other methods. By controlling the growth temperature, it can controllably prepare γ-phase germanium selenide nanosheets of different sizes and high quality.

[0025] (6) The material obtained by this invention is γ-phase germanium selenide nanosheets, which can be directly characterized by atomic force microscopy, scanning electron microscopy, transmission electron microscopy, etc., and provides a feasible path for the subsequent processing of related micro and nano devices.

[0026] (7) The γ-phase germanium selenide prepared by the present invention can be transferred to other substrates, and the mica substrate can be reused multiple times. Attached Figure Description

[0027] Figure 1 The optical microscopy characterization results of the γ-phase germanium selenide nanosheets obtained in Example 1 on a fluorinated mica substrate are shown.

[0028] Figure 2 The Raman spectral characterization results are for the γ-phase germanium selenide nanosheets obtained in Example 1.

[0029] Figure 3 The results are shown by scanning electron microscopy characterization of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0030] Figure 4 The atomic force microscopy characterization results are for the γ-phase germanium selenide nanosheets obtained in Example 1.

[0031] Figure 5 for Figure 4 Atomic force microscopy characterization results at the location indicated by the dashed box.

[0032] Figure 6 The results are Kelvin probe force microscopy characterization of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0033] Figure 7 The transmission electron microscopy characterization results are those of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0034] Figure 8 The results are shown in the high-resolution transmission electron microscopy characterization of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0035] Figure 9 The selected area electron diffraction characterization results are for the γ-phase germanium selenide nanosheets obtained in Example 1.

[0036] Figure 10 The results are the energy dispersive spectroscopy characterization results of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0037] Figure 11 The XPS characterization results are for the Ge 3d orbitals of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0038] Figure 12 The XPS characterization results are for the Se 3d orbitals of the γ-phase germanium selenide nanosheets obtained in Example 1.

[0039] Figure 13 The optical microscopy characterization results are for the γ-phase germanium selenide nanosheets and the amorphous germanium diselenide thin film obtained in Example 1.

[0040] Figure 14 The Raman spectral characterization results are for the amorphous germanium diselenide thin film obtained in Example 1.

[0041] Figure 15 The atomic force microscopy characterization results are those of the amorphous germanium diselenide thin film obtained in Example 1.

[0042] Figure 16 The optical microscopy characterization results and lateral size statistics of the γ-phase germanium selenide nanosheets obtained at a growth temperature of 530℃ in Example 2 are shown.

[0043] Figure 17 The optical microscopy characterization results and lateral size statistics of the γ-phase germanium selenide nanosheets obtained at a growth temperature of 540℃ in Example 3 are shown.

[0044] Figure 18 The optical microscopy characterization results and lateral size statistics of the γ-phase germanium selenide nanosheets obtained at a growth temperature of 570℃ in Example 4 are shown.

[0045] Figure 19 The optical microscopy characterization results and lateral size statistics of the γ-phase germanium selenide nanosheets obtained at a growth temperature of 590℃ in Example 5 are shown.

[0046] Figure 20 The optical microscopy characterization results and lateral size statistics of the γ-phase germanium selenide nanosheets obtained at a growth temperature of 600℃ in Example 6 are shown. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited thereto.

[0048] Example 1

[0049] A 1cm x 1cm fluorinated mica sheet was used as the substrate. The substrate and precursor were placed as follows: First, the fresh surface of the mica substrate was peeled off with 3M tape, and the fresh surface was placed on the graphite sheet. Following the airflow direction from upstream to downstream, the graphite sheet was pushed into the downstream position of the tube furnace. Then, a quartz boat containing high-purity germanium selenide powder was placed at the upstream inlet of the tube furnace. The germanium selenide mass was 4mg, and the distance between the substrate and the heating center was 10.5cm. Argon gas (100sccm) was then introduced into the tube furnace to purge the reaction chamber and remove residual air. The purging time was 20 minutes. The heating program was then set, and when the heating center temperature reached 550℃, the quartz boat containing germanium selenide powder was pushed to the heating center using a magnetic control device. Argon (2 sccm) was used as the carrier gas, and the temperature was maintained for 10 minutes. After 10 minutes, the tube furnace was immediately opened to cool down rapidly. Once the temperature dropped to room temperature, the argon gas was turned off, and finally the tube furnace was opened to remove the sample.

[0050] The γ-phase germanium selenide nanosheets obtained in Example 1 were characterized by optical microscopy, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, Kelvin probe force microscopy, transmission electron microscopy, energy dispersive spectroscopy, and XPS. The results are as follows: Figures 1 to 12 As shown. Optical microscopy characterization reveals that the γ-phase germanium selenide nanosheets grown on the mica substrate are two-dimensional nanosheets with a hexagonal structure. Raman spectroscopy data shows that the sample at 67 cm⁻¹... -1 90cm -1 164cm -1 257cm -1 and 265cm -1 The five typical characteristic peaks of γ-phase germanium selenide are respectively the five characteristic peaks of γ-phase germanium selenide.2 E2, 1 A1、 3 E2, 2 A1 and 3 The A1 peak is consistent with reported data. Scanning electron microscopy characterization indicates that the obtained sample is of high quality and suitable for device fabrication. Atomic force microscopy characterization of γ-phase germanium selenide shows that the thickness of the γ-phase germanium selenide nanosheets is 271.9 nm, and the growth of the γ-phase germanium selenide nanosheets follows a helical dislocation growth mode. Kelvin probe force microscopy characterization of γ-phase germanium selenide shows that the sample has a constant surface potential. Transmission electron microscopy characterization shows that the grown sample has high crystallinity. XPS characterization shows that the peak values ​​corresponding to the Ge 3d orbitals and Se 3d orbitals are consistent with those in the literature, further confirming the successful preparation of γ-phase germanium selenide nanosheets.

[0051] Immediately opening the tube furnace at high temperature caused a rapid temperature drop and a dramatic release of energy, inducing stress in the sample and transforming the crystalline germanium diselenide film into an amorphous germanium diselenide film. The amorphous germanium diselenide film was characterized by optical microscopy, Raman spectroscopy, and atomic force microscopy, with results as follows: Figures 13 to 15 As shown in the figure. Optical microscopy characterization reveals that the precursor inside the tube forms nucleation sites on the surface of the amorphous germanium diselenide thin film, leading to the growth of the γ-phase germanium selenide. Raman spectroscopy data shows that the sample at 172 cm⁻¹... -1 200cm -1 and 215cm -1 The three characteristic peaks of amorphous germanium diselenide are due to interatomic stretching vibrations caused by structural relaxation, resulting in variations in peak values. The peak values ​​of the three characteristic peaks are consistent with reported data. Atomic force microscopy characterization results show that the amorphous germanium diselenide film exhibits a uniform morphology.

[0052] Examples 2 to 6

[0053] By adjusting the heating center temperature of the tube furnace in Example 1 to 530℃, 540℃, 570℃, 590℃, and 600℃, respectively, while keeping other preparation conditions unchanged, controllable growth of γ-phase germanium selenide nanosheets with different lateral dimensions can be achieved. The optical microscopy characterization and size statistics of the γ-phase germanium selenide nanosheet samples obtained in Example 2 are shown below. Figure 16 As shown in Figures 17, 18, 19, and 20, optical microscopy characterization and dimensional statistics demonstrate that lower growth temperatures produce samples with smaller lateral dimensions, while higher temperatures produce samples with larger lateral dimensions.

[0054] Example 7

[0055] By replacing the mica substrate in Example 1 with a silica substrate, while keeping other preparation conditions unchanged, high-quality γ-phase germanium selenide nanosheets can also be prepared.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing γ-phase germanium selenide nanosheets, characterized in that, Includes the following steps: (1) First place the substrate on the graphite sheet, and then push the graphite sheet to the downstream of the horizontal tube furnace according to the direction of airflow from upstream to downstream. (2) Take germanium selenide powder and put it into a quartz boat, and place the quartz boat at the upstream inlet of the tube furnace; (3) Open the gas valve and introduce argon gas into the horizontal tube furnace. Clean the reaction chamber for 30 to 60 minutes before running the equipment. (4) Set the heating program, using argon as the carrier gas. When the heating center is heated to the growth temperature of 500℃ ~ 600℃, push the quartz boat to the heating center of the tube furnace through the magnetic control device. (5) After maintaining the temperature of the center of the heating zone for 9 to 13 minutes, open the furnace cover of the tubular furnace and continue to introduce the carrier gas to cool the furnace until the temperature inside the tube is cooled to room temperature, thus obtaining γ-phase germanium selenide nanosheets. In step (1), the substrate is either a mica substrate or a silicon dioxide substrate; the distance between the substrate and the heating center of the tube furnace is 8.5 cm to 10.5 cm. In step (5), opening the furnace cover of the tubular furnace and continuously introducing carrier gas can rapidly reduce the temperature inside the tube to room temperature. During the rapid cooling process, energy is released violently, generating stress that induces the crystalline germanium diselenide film to transform into an amorphous germanium diselenide film. Furthermore, the precursor inside the tube forms nucleation sites on the surface of the amorphous germanium diselenide film, promoting the growth of γ-phase germanium selenide.

2. The method for preparing γ-phase germanium selenide nanosheets according to claim 1, characterized in that, In step (2), the amount of germanium selenide powder is 3 mg to 5 mg.

3. The method for preparing γ-phase germanium selenide nanosheets according to claim 1, characterized in that, In step (2), the germanium selenide powder is high-purity germanium selenide powder with a purity of 99.99%.

4. The method for preparing γ-phase germanium selenide nanosheets according to claim 1, characterized in that, In step (4), the flow rate of the argon gas is 3 sccm ~ 5 sccm.

5. The method for preparing γ-phase germanium selenide nanosheets according to claim 1, characterized in that, In step (4), the growth temperature is 530℃ ~ 570℃.

6. The method for preparing γ-phase germanium selenide nanosheets according to claim 1, characterized in that, This also includes closing the argon gas valve after the growth process is complete.

7. The method for preparing γ-phase germanium selenide nanosheets according to claim 1, characterized in that, In step (5), the temperature is maintained for 10 to 12 minutes.

Images