A method for preparing single crystal β-gallium oxide nanosheets

Abstract

The present invention discloses a method for preparing single-crystalline β-gallium oxide nanosheets. The preparation method comprises: using chemical vapor deposition (CVD) to directly oxidize metallic gallium using oxygen as an oxidant, and then growing the single-crystalline β-gallium oxide nanosheets on the surface of a confined substrate material. The present invention utilizes spatial confinement to synthesize two-dimensional ultrathin single-crystalline β-gallium oxide nanosheets. Using oxygen as an oxidant, the gallium oxide nanosheets are directly oxidized to produce the nanosheets. This method requires no catalyst, is simple to manufacture, and has low production costs. Large-sized, high-quality, thickness-controllable single-crystalline β-gallium oxide nanosheets are produced, and can be used for research and application in ultraviolet photodetectors and high-power electronic devices.

Description

Technical Field

[0001] The present invention specifically relates to a method for preparing an ultra-thin single-crystal β-gallium oxide nanosheet, and belongs to the technical field of semiconductor materials. Background Art

[0002] With the rapid development of the semiconductor industry, the application scope and demand for semiconductor materials have increased year by year. Wide-bandgap semiconductors, in particular, play a vital role in high-power semiconductor devices, ultraviolet detection, and ultraviolet communications. β-GaO, a fourth-generation wide-bandgap semiconductor material, has attracted extensive attention and research due to its direct bandgap, ultra-wide bandgap, high breakdown field strength, and high thermal and chemical stability.

[0003] Compared to bulk materials, nanomaterials possess unique properties such as larger surface area, quantum size confinement effects, and quantum tunneling, as well as unusual physical characteristics (e.g., high-density two-dimensional electron gas, anomalous photoresponse, massless Dirac fermions, thickness-tuned band gaps, and Mott insulator states). Consequently, much recent research has focused on using β-gallium oxide nanomaterials to fabricate higher-performance β-gallium oxide-based devices and novel devices. Single-crystal GaO nanosheets, in particular, hold broad application prospects in novel two-dimensional optoelectronics and van der Waals heterojunction stacked devices.

[0004] The current preparation method of gallium oxide nanosheets is mainly chemical vapor deposition. These preparation methods mainly use gallium and its compounds as gallium sources, and grow gallium oxide nanosheets by catalytic growth methods of different metal nanoparticles (such as gold (CN111811645B, CN114107945A), platinum (CN109056057B, CN109881246B, Small 2019, 15, 1900580), etc.). Although these methods can obtain gallium oxide nanosheets, it is difficult to avoid the problem of metal catalyst residue; and the use of precious metals will undoubtedly greatly increase production costs. Although there are reported methods for preparing gallium oxide nanosheets by direct oxidation of layered gallium compounds (such as GaSe or GaS), such methods rely on mechanically exfoliated layered gallium compounds (such as GaSe or GaS) as precursors, and there are problems such as uncontrollable thickness and high labor costs. Therefore, it is urgent to develop a simple and easy-to-operate non-catalytic growth method for β-gallium oxide single crystal nanosheets. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for preparing single-crystal β-gallium oxide nanosheets to overcome the shortcomings of the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] An embodiment of the present invention provides a method for preparing single-crystalline β-gallium oxide nanosheets, which includes: using a chemical vapor deposition method to directly oxidize metallic gallium using oxygen as an oxidant, and growing single-crystalline β-gallium oxide nanosheets on the surface of a substrate material with a confined space.

[0008] In some embodiments, the preparation method comprises:

[0009] Gallium metal and a substrate material with a confined space are sequentially placed in a reaction chamber of a chemical vapor deposition device along an oxygen gas flow direction, with a selected distance between the gallium metal and the substrate material with a confined space;

[0010] The temperature in the reaction chamber is raised to 900-1050° C., oxygen is introduced and reacted for 5-30 minutes to obtain single crystal β-gallium oxide nanosheets.

[0011] The embodiment of the present invention also provides single crystal β-gallium oxide nanosheets prepared by the above preparation method.

[0012] The embodiment of the present invention also provides the application of the single crystal β-gallium oxide nanosheet in the preparation of ultraviolet photodetectors and high-power electronic devices.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention achieves the synthesis of two-dimensional ultra-thin single-crystalline β-gallium oxide nanosheets by introducing a spatial confinement method. Oxygen is used as an oxidant to directly oxidize metallic gallium to prepare the gallium oxide nanosheets. No catalyst is required, the process is simple, and the production cost is low. Large-sized, high-quality, and thickness-controllable single-crystalline β-gallium oxide nanosheets are prepared, which can be used for research and application in ultraviolet photodetectors and high-power electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 Schematic diagram of the growth of single crystal β-gallium oxide nanosheets provided in a typical embodiment of the present invention.

[0017] Figure 2 This is an X-ray diffraction pattern of a single-crystal β-gallium oxide nanosheet prepared in a typical embodiment of the present invention.

[0018] Figure 3This is a Raman spectrum of a single-crystal β-gallium oxide nanosheet prepared in a typical embodiment of the present invention.

[0019] Figure 4a and Figure 4b The figures are SEM and AFM images of single crystal β-gallium oxide nanosheets prepared in a typical embodiment of the present invention.

[0020] Figure 5 This is the SEM morphology of the non-confined grown gallium oxide sample in Comparative Example 1. DETAILED DESCRIPTION

[0021] In response to the problems of metal catalyst dependence and high process complexity in the preparation of existing gallium oxide nanosheets, the inventors of this case, after long-term research and extensive practice, were able to propose the technical solution of the present invention. The main method is to introduce a method of spatially confined growth. This method does not require a vacuum environment, has a simple process, good universality and repeatability, and does not require the use of precious metal catalysts. It can directly prepare single-crystalline β-gallium oxide nanosheets with advantages such as high quality and controllable thickness on a substrate.

[0022] The following will further explain the technical solution, its implementation process and principles. However, it should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described here one by one.

[0023] As one aspect of the technical solution of the present invention, the method for preparing single-crystalline β-gallium oxide nanosheets involves: using a chemical vapor deposition method to directly oxidize metallic gallium using oxygen as an oxidant, and growing single-crystalline β-gallium oxide nanosheets on the surface of a substrate material with a confined space.

[0024] As one of the preferred solutions, the preparation method may specifically include:

[0025] Gallium metal and a substrate material with a confined space are sequentially placed in a reaction chamber of a chemical vapor deposition device along an oxygen gas flow direction, with a selected distance between the gallium metal and the substrate material with a confined space;

[0026] The temperature in the reaction chamber is raised to 900-1050° C., oxygen is introduced and reacted for 5-30 minutes to obtain single crystal β-gallium oxide nanosheets.

[0027] Furthermore, the selected spacing is 2 to 10 cm.

[0028] As one of the preferred solutions, the preparation method includes: stacking at least two substrates relative to each other to form a substrate material with a confined space. The present invention introduces a spatial confinement method to achieve the synthesis of two-dimensional ultrathin β-gallium oxide nanosheets.

[0029] As one of the more preferred solutions, the preparation method specifically includes:

[0030] Inert gas is introduced into the reaction chamber at a flow rate of 200 to 500 sccm for 5 to 10 minutes;

[0031] The inert gas flow rate is reduced to 100-300 sccm, and hydrogen is introduced (to ensure that gallium is not oxidized before the reaction temperature) at a flow rate of 20-50 sccm, and then the temperature in the reaction chamber is heated to 900-1050° C.;

[0032] Then, the hydrogen gas is turned off and oxygen gas is introduced at a gas flow rate of 1 to 50 sccm to obtain the single crystal β-gallium oxide nanosheet.

[0033] Furthermore, during the reaction process, the present invention uses oxygen as an oxidant to directly oxidize metallic gallium to prepare gallium oxide nanosheets, which does not require a catalyst, has a simple process, and has low production costs.

[0034] Furthermore, the inert gas may be argon, but is not limited thereto.

[0035] As one of the preferred solutions, the reaction time is 5 to 30 minutes.

[0036] Furthermore, the material of the substrate may include but is not limited to any one of silicon wafer, quartz, gallium nitride, etc. Other substrate materials can also be used to grow two-dimensional gallium oxide through the spatial confinement method.

[0037] As one of the more preferred embodiments, please refer to Figure 1 As shown, the spatial confinement growth method for preparing high-quality, large-size single-crystalline gallium oxide nanosheets provided by the present invention uses a chemical vapor deposition device (CVD), and the specific steps are as follows:

[0038] 1) Weigh 5-50 mg of gallium metal into a tungsten boat, and transfer the tungsten boat into a one-inch quartz tube;

[0039] 2) placing the quartz tube in step 1) in a tube furnace, and positioning the tungsten boat in the center of the temperature zone of the tube furnace;

[0040] 3) Place the quartz plate containing the substrate material of the finite domain 2 to 10 cm behind the tungsten boat in the quartz tube;

[0041] 4) Pass high-purity argon gas into the quartz tube to clean the quartz tube at a flow rate of 200-500 sccm for 5-10 minutes;

[0042] 5) Reduce the flow rate of argon to 100-300 sccm and introduce hydrogen at a flow rate of 20-50 sccm. Under these conditions, heat the tube furnace to 900-1050°C;

[0043] 6) After reaching the target temperature, the hydrogen gas is turned off, and 1 to 50 sccm of oxygen is introduced, and the temperature is kept at this temperature for 5 to 30 minutes to obtain the single crystal β-gallium oxide (Ga2O3) nanosheets.

[0044] Among them, the substrate material is two pieces stacked together face to face.

[0045] Another aspect of the embodiments of the present invention further provides a single crystal β-gallium oxide nanosheet prepared by the above preparation method, which has a two-dimensional structure and a thickness of 10 to 100 nanometers.

[0046] Furthermore, the length of the single crystal β-gallium oxide nanosheet can reach more than 100 μm, and the width can reach more than 10 μm, for example, tens of microns.

[0047] In summary, the method for preparing single-crystalline β-gallium oxide nanosheets of the present invention, by controlling the O2 gas flow rate, growth temperature, and growth time, can rapidly produce large-sized, high-quality, and thickness-controlled single-crystalline β-gallium oxide nanosheets, providing materials for research into two-dimensional gallium oxide optoelectronics. The high-quality single-crystalline β-gallium oxide nanosheets prepared by the present invention can be used in research and applications such as ultraviolet photodetectors and high-power electronic devices.

[0048] In order to make the purpose, technical solution and application of the present invention clearer, the technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The implementation conditions adopted in the following examples can be further adjusted according to actual needs. The implementation conditions not specified are usually the conditions in routine experiments.

[0049] Example 1

[0050] 1) Weigh 20 mg of metallic gallium and place it in a tungsten boat. Transfer the tungsten boat to a one-inch quartz tube.

[0051] 2) placing the quartz tube in step 1) in a tube furnace, and positioning the tungsten boat in the center of the temperature zone of the tube furnace;

[0052] 3) Place the quartz plate containing the substrate material of the finite domain 5 cm behind the tungsten boat in the quartz tube;

[0053] 4) Pass high-purity argon gas into the quartz tube to clean the quartz tube at a flow rate of 300 sccm for 8 minutes;

[0054] 5) Reduce the flow rate of argon to 200 sccm and introduce hydrogen at a flow rate of 30 sccm. Under these conditions, heat the tube furnace to 1000°C.

[0055] 6) After reaching the target temperature, the hydrogen gas was turned off, and 30 sccm of oxygen was introduced, and the temperature was kept at this temperature for 20 minutes to obtain the single crystal β-gallium oxide nanosheets.

[0056] Example 2

[0057] 1) Weigh 30 mg of metallic gallium and place it in a tungsten boat. Transfer the tungsten boat to a one-inch quartz tube.

[0058] 2) placing the quartz tube in step 1) in a tube furnace, and positioning the tungsten boat in the center of the temperature zone of the tube furnace;

[0059] 3) Place the quartz plate containing the substrate material of the finite domain 8 cm behind the tungsten boat in the quartz tube;

[0060] 4) High-purity argon gas was introduced into the quartz tube to clean the tube at a flow rate of 400 sccm for 6 minutes;

[0061] 5) Reduce the flow rate of argon to 250 sccm and introduce hydrogen at a flow rate of 40 sccm. Under these conditions, heat the tube furnace to 950°C.

[0062] 6) After reaching the target temperature, the hydrogen gas was turned off, and 20 sccm of oxygen was introduced, and the temperature was kept at this temperature for 15 minutes, thereby obtaining the single crystal β-gallium oxide nanosheets.

[0063] Example 3

[0064] 1) Weigh 50 mg of metallic gallium and place it in a tungsten boat. Transfer the tungsten boat to a one-inch quartz tube.

[0065] 2) placing the quartz tube in step 1) in a tube furnace, and positioning the tungsten boat in the center of the temperature zone of the tube furnace;

[0066] 3) Place the quartz plate containing the substrate material of the finite domain 10 cm behind the tungsten boat in the quartz tube;

[0067] 4) Pass high-purity argon gas into the quartz tube to clean the quartz tube at a flow rate of 500 sccm for 5 minutes;

[0068] 5) Reduce the argon flow rate to 100 sccm and introduce hydrogen at a flow rate of 50 sccm. Under these conditions, heat the tube furnace to 900°C.

[0069] 6) After reaching the target temperature, the hydrogen gas was turned off, and 50 sccm of oxygen was introduced, and the temperature was kept at this temperature for 30 minutes to obtain the single crystal β-gallium oxide nanosheets.

[0070] Example 4

[0071] 1) Weigh 5 mg of metallic gallium and place it in a tungsten boat. Transfer the tungsten boat to a one-inch quartz tube.

[0072] 2) placing the quartz tube in step 1) in a tube furnace, and positioning the tungsten boat in the center of the temperature zone of the tube furnace;

[0073] 3) Place the quartz plate containing the substrate material of the finite domain 2 cm behind the tungsten boat in the quartz tube;

[0074] 4) Pass high-purity argon gas into the quartz tube to clean the quartz tube at a flow rate of 200 sccm for 10 minutes;

[0075] 5) Reduce the flow rate of argon to 300 sccm and introduce hydrogen at a flow rate of 20 sccm. Under these conditions, heat the tube furnace to 1050°C.

[0076] 6) After reaching the target temperature, the hydrogen gas was turned off, and 1 sccm of oxygen was introduced, and the temperature was kept at this temperature for 5 minutes to obtain the single crystal β-gallium oxide nanosheets.

[0077] The inventors of this case also characterized and analyzed the prepared single crystal β-gallium oxide nanosheets using Example 1 as an example, and the results are as follows:

[0078] Figure 2 The XRD pattern of single crystal β-gallium oxide nanosheets is shown. All the strong diffraction peaks of β-Ga2O3 shown in the figure can correspond to the standard X-ray diffraction pattern (JCPDS, No.43-1012), among which the peak of (111) crystal plane is the strongest. No other crystalline phases of gallium oxide were observed in the above XRD test results, which indicates that the experimental growth is a high-purity single-phase β-Ga2O3. In addition, the sample was tested by Raman spectroscopy, and the results are as follows Figure 3 In the Raman spectrum of β-Ga2O3, the wavelengths at 112, 145, 169, 200, 319, 349, 416, 474, 629, 653, and 765 cm -1 Peaks are observed at , and the positions of these peaks are consistent with the characteristics of β-Ga2O3. The surface sample is β-Ga2O3 with good crystallization quality.

[0079] The SEM and AFM images of the single crystal β-gallium oxide nanosheets are shown in Figure 2. Figure 4a and Figure 4b As shown in the figure, the scanning electron microscope (SEM) image shows that the obtained sample is a nanosheet; the thickness of the sample was tested, and the atomic force microscope (AFM) results showed that the thickness of the prepared gallium oxide nanosheet can reach 10 nanometers, as shown in the figure. Figure 4b The inset in the upper left corner shows the height curve at the white line in the figure; this inset provides information on the sample thickness—10 nanometers. Furthermore, the length can reach over 100 micrometers, and the width can reach tens of micrometers.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 1 is that the substrate material does not have a confined space. The SEM morphology of the non-confined growth gallium oxide sample is as follows: Figure 5 As shown, the sample is a mixture of disordered nanowires and nanosheets, and the thickness may exceed hundreds of nanometers.

[0082] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0083] It should be understood that the above examples are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for preparing single-crystal β-gallium oxide nanosheets, characterized in that: include: The two substrates are stacked relative to each other to form a confined space on the substrates; Gallium metal and a substrate material with a confined space are sequentially placed in a reaction chamber of a chemical vapor deposition apparatus along an oxygen gas flow direction, with a selected spacing of 2 to 10 cm between the gallium metal and the substrate with the confined space. The temperature in the reaction chamber is raised to 900-1050°C, oxygen is introduced, and the reaction is carried out for 5-30 minutes to grow single-crystalline β-gallium oxide nanosheets on the surface of the confined substrate. The single-crystalline β-gallium oxide nanosheets have a length of greater than 100 µm and a width of greater than 10 µm. The single-crystalline β-gallium oxide nanosheets have a two-dimensional structure and a thickness of 10-100 nm.

2. The preparation method according to claim 1, characterized in that include: Inert gas was introduced into the reaction chamber at a flow rate of 200-500 sccm for 5-10 min. The inert gas flow rate is reduced to 100-300 sccm, and hydrogen gas is introduced at a flow rate of 20-50 sccm, and then the temperature in the reaction chamber is heated to 900-1050° C.; Then, the hydrogen gas is turned off and oxygen gas is introduced at a gas flow rate of 1 to 50 sccm to obtain the single crystal β-gallium oxide nanosheet.

3. The preparation method according to claim 1, wherein: The substrate material is selected from any one of silicon wafer, quartz and gallium nitride.

4. The preparation method according to claim 2, wherein: The inert gas is argon.

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