A two-dimensional nano-patterned substrate and a method for preparing the same

Abstract

The application provides a two-dimensional nanometer patterning substrate and a preparation method. A graphene film is prepared on a supporting substrate; a metal film is deposited on the graphene film; the metal film is converted into discontinuous metal nanoparticles; the graphene pattern is etched by using the metal nanoparticles as a mask; the metal nanoparticle mask on the graphene pattern is removed; and a nitride material is grown on the graphene pattern. Compared with existing electron beam exposure, nano-imprinting and nano-sphere mask schemes, the two-dimensional nanometer patterning substrate and the preparation method are simple and feasible, and the cost can be effectively controlled. In addition, the two-dimensional nanometer patterning substrate and the preparation method are suitable for large-size and batch construction, and the above technical details are suitable for the advantages. Finally, the nanometer pattern size and other geometric parameters have high flexibility, which is important for promoting subsequent lateral epitaxy of high-quality nitride materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material synthesis, in particular to a two-dimensional nano-patterned substrate and a preparation method thereof. BACKGROUND

[0002] Due to the limitations of the preparation efficiency and production cost of high-quality nitride single crystal substrates, mainstream nitride material epitaxy is usually carried out on a heteroepitaxial substrate such as sapphire. However, the "large mismatch" epitaxial interface will result in high dislocation density and large residual stress in the epitaxial layer, which poses a challenge to the development of high-performance nitride-based optoelectronic devices. The new van der Waals epitaxy technology of nitride uses two-dimensional flexible materials (such as graphene and h-BN) as an interlayer, which makes the epitaxial layer and the supporting substrate interact with each other through weak van der Waals force, which can greatly improve the crystal quality of the nitride epitaxial layer and eliminate internal stress. However, the graphene surface lacks dangling bonds, and it is difficult for nitride to nucleate on its surface during the initial growth. In view of this technical problem, related work proposes to use patterned graphene as an interlayer to selectively nucleate nitride at the "exposed" supporting substrate position, and then increase the lateral growth rate of nitride to make it laterally epitaxial and merge, which can greatly improve the crystal quality of nitride materials.

[0003] Here, the construction of the two-dimensional nano-patterned substrate is the key to realizing the lateral epitaxy of high-quality nitride materials. At present, the mainstream nano-pattern preparation schemes include electron beam exposure, nano-imprinting and nano-sphere mask technologies. Among them, the processing efficiency of electron beam exposure is low, and the preparation of large-area structures takes a long time; nano-imprinting requires a specific template, and the geometric parameter control of the nano-pattern is limited; polystyrene nano-spheres are easy to introduce impurities during the transfer, etching and cleaning processes. Therefore, how to realize large-size, low-cost and high-efficiency and highly controllable preparation of two-dimensional nano-patterned substrates still faces challenges; it is crucial to develop batch preparation technology of two-dimensional nano-patterned substrates. SUMMARY

[0004] Therefore, the present application provides a two-dimensional nano-patterned substrate with high production efficiency, good flexibility of pattern structure size design and clean sample surface, and a preparation method thereof. The technical scheme adopted by the present application is as follows:

[0005] One of the objects of the present application is to provide a preparation method of a two-dimensional nano-patterned substrate, comprising the following steps:

[0006] Preparation of a graphene film on a supporting substrate;

[0007] Preparation of metal nano-particles on the surface of the graphene film;

[0008] Etching of a graphene pattern under the metal nano-particle mask;

[0009] removing the metal nanoparticle mask on the graphene;

[0010] growing nitride material on the graphene pattern.

[0011] In some embodiments, the step of preparing a graphene film on a supporting substrate specifically comprises the following steps: preparing a graphene film on the supporting substrate by chemical vapor deposition or liquid phase exfoliation.

[0012] In some embodiments, the supporting substrate comprises a nitride heteroepitaxy substrate or a nitride single crystal template, the nitride heteroepitaxy substrate comprises sapphire, silicon carbide or silicon; the nitride single crystal template comprises aluminum nitride or gallium nitride single crystal.

[0013] In some embodiments, the step of preparing metal nanoparticles on the surface of the graphene film specifically comprises the following steps: depositing a metal film on the graphene film by electron beam evaporation, thermal evaporation or magnetron sputtering, the metal film comprises gold, silver, copper or aluminum; and then annealing the metal film at a high temperature of 500-800 degrees Celsius to convert the metal film into discontinuous nanoparticles.

[0014] In some embodiments, the step of preparing metal nanoparticles on the surface of the graphene film can also comprise the following steps: spin-coating a solution of discontinuous metal nanoparticles on the graphene surface, the solution of discontinuous metal nanoparticles comprises a solution of nano-gold, nano-silver, nano-copper or nano-aluminum.

[0015] In some embodiments, the step of etching a graphene pattern with the nanoparticle mask specifically comprises the following steps: using the nanoparticles as a mask to etch and remove the exposed graphene film by plasma etching technology; and removing the nanoparticles by chemical reaction provided in the etching solution to obtain a nano-patterned graphene structure on the supporting substrate, thereby completing the construction of a two-dimensional nano-patterned substrate.

[0016] In some embodiments, the step of removing the metal nanoparticle mask on the graphene comprises selectively etching and removing the metal nanoparticles by an etching solution.

[0017] In some embodiments, the step of growing nitride material on the graphene pattern specifically comprises the following steps: growing nitride material on the graphene pattern by a metal-organic chemical vapor deposition device.

[0018] The second object of the present application also provides a two-dimensional nano-patterned substrate prepared by the method for preparing a two-dimensional nano-patterned substrate.

[0019] The application adopts the technical solutions, and has the following beneficial effects:

[0020] The two-dimensional nanometer patterning substrate and the preparation method provided by the application are used for preparing a graphene film on a support substrate, depositing a metal film on the graphene film, converting the metal film into discontinuous metal nanoparticles, etching a graphene pattern through the metal nanoparticle mask, removing the metal nanoparticle mask through solution corrosion, and growing a nitride material on the graphene pattern. Compared with the existing electron beam exposure, nanoimprint and nano ball mask solutions, the method provided by the application is simple and feasible, and the cost can be effectively controlled. Secondly, it is suitable for large-size and batch construction, and the above technical details are applicable to this advantage. Finally, the nanometer pattern size and other geometric parameters have high flexibility, which is important for promoting the lateral epitaxy of high-quality nitride materials. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the application or the prior art. Obviously, the drawings described below are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 The step flow chart of the preparation method of the two-dimensional nanometer patterning substrate provided by the embodiments of the application.

[0023] Figure 2 The two-dimensional nanometer patterning substrate preparation and nitride lateral epitaxy process flow chart provided by the embodiments of the application. DETAILED DESCRIPTION

[0024] The embodiments of the application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application.

[0025] In the description of the application, it should be understood that the terms "upper", "lower", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the application.

[0026] In addition, the terms "first", "second", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0027] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples.

[0028] Please refer to Figure 1 A method for preparing a two-dimensional nano-patterned substrate provided by an embodiment of the present application comprises the following steps:

[0029] Step S110: preparing a graphene film on a support substrate.

[0030] In some embodiments, the step of preparing a graphene film on a support substrate specifically comprises the following steps: preparing a graphene film on the support substrate by chemical vapor deposition or liquid phase exfoliation.

[0031] In some embodiments, the support substrate comprises a nitride heteroepitaxy substrate or a nitride single crystal template, the nitride heteroepitaxy substrate comprises sapphire, silicon carbide or silicon, and the nitride single crystal template comprises aluminum nitride or gallium nitride single crystal.

[0032] Specifically, for the chemical vapor deposition method: first, graphene is grown on a catalytic metal copper or nickel foil by using a low-pressure chemical vapor deposition device, and the number of layers, crystal quality and other characteristics of the graphene can be directly controlled by the growth process parameters; then, the graphene on the catalytic metal foil can be transferred to the surface of the support substrate by using a conventional polymer-assisted wet transfer process; a support substrate / graphene film composite structure is formed.

[0033] Specifically, for the liquid phase exfoliation method, graphene nanometer / micrometer sheets exist in the form of a solution, which can be directly prepared on the support substrate by spin coating, and the number of layers of graphene can be controlled by adjusting the solution concentration or coating process parameters.

[0034] Based on the current preparation process, the graphene film on the support substrate has a continuous and complete morphology.

[0035] Step S120: preparing metal nanoparticles on the surface of the graphene film.

[0036] Specifically, in the step of preparing metal nanoparticles on the surface of the graphene film, the following steps can also be selected:

[0037] Step S121: depositing a metal film on the graphene film;

[0038] In some embodiments, the step of depositing a metal film on the graphene film specifically comprises the following step: depositing a metal film on the graphene film by electron beam evaporation, thermal evaporation or magnetron sputtering, and the metal film is selected from gold, silver, copper or aluminum.

[0039] A certain thickness of metal film is deposited on the support substrate / graphene by conventional techniques such as electron beam evaporation, thermal evaporation or magnetron sputtering, and the metal is preferably selected from gold, silver, copper and aluminum, which have good stability and low melting point. The thickness of the metal film can be effectively controlled, and the related deposition method meets the preparation of inch-level material film.

[0040] Step S122: converting the metal film into non-continuous metal nanoparticles.

[0041] In some embodiments, the step of converting the metal film into non-continuous metal nanoparticles specifically comprises the following step: converting the metal film into non-continuous nanoparticles by high-temperature thermal annealing at 500-800 degrees Celsius.

[0042] The metal film on the support substrate / graphene is converted into a non-continuous nanoparticle structure by high-temperature thermal annealing, which requires a temperature of 500-800 degrees Celsius. The geometric parameters such as the structure size, height and distribution density of the nanoparticles can be achieved by adjusting the thickness of the metal film and the annealing conditions. In this process, the support substrate and graphene (growth temperature 1000 degrees Celsius) have good stability and can maintain their intrinsic properties.

[0043] In some embodiments, the step of preparing non-continuous metal nanoparticles on graphene further comprises the following step: spin-coating a solution of non-continuous metal nanoparticles on the two-dimensional graphene surface, wherein the solution of non-continuous metal nanoparticles includes a solution of nano-gold, nano-silver, nano-copper or nano-aluminum.

[0044] Step S130: etching graphene patterns using the metal nanoparticle mask.

[0045] In some embodiments, the step of etching graphene patterns using the nanoparticle mask specifically comprises the following steps: using the nanoparticles as a mask, and etching and removing the exposed graphene film by plasma etching technology; and removing the nanoparticles by chemical reaction provided in the etching solution to obtain a nano-patterned graphene structure on the support substrate, thereby completing the construction of a two-dimensional nano-patterned substrate.

[0046] The metal nanoparticles on the support substrate / graphene are used as a mask, and the exposed graphene film is etched and removed by plasma etching technology. According to the number of graphene layers and other characteristics, the etching power and time parameters are matched. Here, the graphene covered by the metal nanoparticles will be retained and the structure will remain intact.

[0047] Step S140: removing the metal nanoparticle mask on the graphene.

[0048] Further, the metal nanoparticle mask is etched and removed by a chemical reaction provided in the etching solution, obtaining a nano-patterned graphene structure on the support substrate, and completing the construction of the two-dimensional nano-patterned substrate.

[0049] Step S150: growing a nitride material on the graphene pattern.

[0050] In some embodiments, the step of growing a nitride material on the graphene pattern specifically includes the following steps: using a metal-organic chemical vapor deposition device to grow a nitride material on the graphene pattern.

[0051] Using a metal-organic chemical vapor deposition device, a nitride material is grown on the two-dimensional nano-patterned substrate. By virtue of the difficulty of nucleation of the nitride material on graphene, the nitride material preferentially nucleates and grows (in a growth direction perpendicular to the epitaxial interface) at the "exposed" support substrate not covered by graphene; then, the nitride growth temperature and V / III are adjusted to increase the lateral epitaxial growth rate of the nitride, so that the epitaxial layers merge. In this process, dislocations are pulled closer to each other by the driving force of lateral epitaxy, and merge and annihilate, which can effectively reduce the dislocation density of the nitride material.

[0052] The two-dimensional nano-patterned substrate and the preparation method provided by the above embodiments are simple and feasible, and the cost can be effectively controlled compared with existing electron beam exposure, nano-imprinting and nano-sphere mask solutions. Secondly, it is suitable for large-size and batch construction, and the above technical details are applicable to this advantage. Finally, the nano-pattern size and other geometric parameters have high flexibility, which is important for promoting the subsequent lateral epitaxy of high-quality nitride materials.

[0053] The two-dimensional nano-patterned substrate prepared by the present application can also be used for lateral epitaxy of traditional silicon-based, arsenide and other semiconductor materials to improve the crystal quality thereof. Based on high-quality semiconductor materials, it can be used for subsequent device structure epitaxy and preparation.

[0054] Embodiments

[0055] The present application will be described in detail below in conjunction with the drawings and specific embodiments, but the present application is not limited to the following embodiments.

[0056] attached Figure 2 For two-dimensional nanometer patterning substrate preparation and nitride lateral epitaxy process, here taking sapphire support substrate, graphene, Cu metal layer and AlN nitride epitaxial layer as an example, the specific implementation process is as follows:

[0057] (1) A 2-inch single-throw sapphire is used as a support substrate, with a thickness of 230 microns and a surface roughness of less than 0.5 nanometers. Single-layer graphene material is grown on a catalytic copper foil using chemical vapor deposition, and a 5 cm x 5 cm single-layer graphene film is transferred to the surface of the sapphire substrate using PMMA-assisted wet transfer to obtain the sapphire / graphene composite structure shown in (1). Figure 2

[0058] (2) A 100-nanometer-thick copper metal film is deposited on the sapphire / graphene using electron beam evaporation, with a deposition rate of less than 0.1 nanometer / second and a chamber pressure of less than 5 x 10 -4 pascal, obtaining the multi-layer structure of sapphire / graphene / copper metal layer shown in (2). Figure 2

[0059] (3) Anneal the sapphire / graphene / copper metal layer structure at 800 degrees Celsius in a nitrogen atmosphere at normal pressure for 1 minute; the copper metal film, due to its poor thermal stability, condenses to form metal particles with a diameter of 100-500 nanometers; the graphene remains its complete and continuous structural characteristics, as shown in (3). Figure 2

[0060] (4) Etch the graphene that is not masked by the copper metal nanoparticles using nitrogen plasma etching, with an etching power of 50% for 5 minutes and a gas flow rate of 50 liters / minute; the exposed single-layer graphene can be completely etched clean; the copper nanoparticle pattern structure is transferred to the underlying graphene, as shown in (4). Figure 2

[0061] (5) Soak the structure in (4) in a saturated solution of sodium persulfate for 5 minutes to allow the copper nanoparticles to fully react with the etching solution and be completely removed, obtaining the two-dimensional nanometer patterning substrate shown in (5). Figure 2 Figure 2

[0062] ​​​​​​(6) Put the two-dimensional nano-patterned substrate into a metal-organic chemical vapor deposition device, and input TMAl and NH3 as source materials for AlN epitaxial growth. First, prepare AlN nucleation points at 950 degrees Celsius on the "bare" sapphire position, and the growth time is 5 minutes; increase the growth temperature to 1200 degrees Celsius, and alternately input NH3 to greatly increase the lateral growth rate of AlN, and the growth time is 1 hour. The thickness of the epitaxially grown AlN is about 2 microns, and the dislocation density can be controlled below 5×10 8 / square centimeters, and the high-quality AlN epitaxial layer based on the two-dimensional nano-patterned substrate is as shown in (6). Figure 2

[0063] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0064] The above is only a preferred embodiment of the present application, and only the technical principles of the present application are specifically described. These descriptions are only to explain the principles of the present application, and cannot be interpreted in any way as a limitation on the protection scope of the present application. Based on the explanations herein, any modifications, equivalent replacements and improvements made within the spirit and principles of the present application, and other specific embodiments of the present application that can be conceived by those skilled in the art without creative labor, should be included within the protection scope of the present application.​

Claims

1. A method for preparing a two-dimensional nano-patterned substrate, characterized by, The method comprises the following steps: preparing a graphene film on a support substrate; preparing metal nanoparticles on the surface of the graphene film; etching a graphene pattern by using the metal nanoparticle mask; removing the metal nanoparticle mask on the graphene; growing a nitride material on the graphene pattern; In the step of preparing metal nanoparticles on the surface of the graphene film, the following steps are further included: depositing a metal film on the graphene film by using electron beam evaporation, thermal evaporation or magnetron sputtering, wherein the metal film is made of gold, silver, copper or aluminum; and then performing high-temperature thermal annealing at 500-800 degrees Celsius to convert the metal film into non-continuous nanoparticles. The support substrate comprises a nitride heteroepitaxy substrate or a nitride single crystal template, wherein the nitride heteroepitaxy substrate comprises sapphire, silicon carbide or silicon, and the nitride single crystal template comprises aluminum nitride or gallium nitride single crystal. In the step of preparing metal nanoparticles on the surface of the graphene film, the following steps can also be selected: spinning a non-continuous metal nanoparticle solution on the surface of the graphene, wherein the non-continuous metal nanoparticle solution comprises a solution of nano-gold, nano-silver, nano-copper or nano-aluminum; In the step of etching a graphene pattern by using the nanoparticle mask, the following steps are further included: using the nanoparticles as a mask to remove the exposed graphene film by using plasma etching technology; and removing the nanoparticles by chemical reaction provided in the etching solution to obtain a nano-patterned graphene structure on the support substrate, thereby completing the construction of a two-dimensional nano-patterned substrate.

2. The method for preparing a two-dimensional nanopatterned substrate as described in claim 1, characterized in that, In the step of preparing a graphene film on a support substrate, the following steps are further included: preparing a graphene film on the support substrate by chemical vapor deposition or liquid phase exfoliation.

3. The method for preparing a two-dimensional nanopatterned substrate as described in claim 1, characterized in that, In the step of removing the metal nanoparticle mask on the graphene, the metal nanoparticles are selectively removed by etching solution.

4. The method for preparing a two-dimensional nanopatterned substrate as described in claim 1, characterized in that, In the step of growing a nitride material on the graphene pattern, the following steps are further included: growing a nitride material on the graphene pattern by using a metal-organic chemical vapor deposition device.

5. A two-dimensional nanometer patterned substrate, characterized in that, The two-dimensional nano-patterned substrate is prepared by the method of any one of claims 1-4.

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