Method for preparing self-supporting diamond film

Abstract

The present invention relates to a method for preparing a self-supporting diamond film, comprising: preparing a phosphorene layer on the (111) crystal plane of an Au substrate, then preparing a diamond film on the phosphorene layer, taking it out after cooling, degrading the phosphorene layer, peeling off the Au substrate, and obtaining a self-supporting diamond film. In the preparation method of the present invention, since Au has excellent ductility and diamond is very hard, stress can be gradually released during the cooling process to ensure that the diamond film will not break, and the obtained diamond film has almost no stress; in addition, since Au is soft, the Au substrate will break during the cooling process and leak the phosphorene layer, so after the product is taken out, the phosphorene layer will react with water, oxygen, etc., degrade, and finally the Au substrate will be automatically peeled off, without the need to use concentrated nitric acid and hydrofluoric acid, which is not only safe and environmentally friendly, but also quick and convenient.

Description

Technical Field

[0001] The invention relates to the field of diamond technology, in particular to a method for preparing a self-supporting diamond film. Background Art

[0002] At present, diamond films are usually grown by heteroepitaxial method, and then a mixture of concentrated nitric acid and hydrofluoric acid is used to completely etch a heterogeneous substrate such as a single crystal silicon substrate to obtain a self-supporting diamond film. However, due to the large difference in thermal expansion coefficients between the heterogeneous substrate and diamond, there is a large thermal stress between the diamond film and the heterogeneous substrate when the heterogeneous substrate exists. When the heterogeneous substrate is etched away, the stress is released, which easily causes the diamond film to break. In addition, concentrated nitric acid and hydrofluoric acid solutions are highly corrosive, which is very dangerous in production operations, and difficult to be harmlessly disposed of in the later stage, which will cause harm to the environment. Summary of the invention

[0003] Based on this, it is necessary to provide a method for preparing a self-supporting diamond film to address the above problems. The preparation method can grow a high-quality diamond film, gradually release stress during the cooling process, and automatically peel off the Au substrate to obtain a self-supporting diamond film with almost no stress.

[0004] A method for preparing a self-supporting diamond film comprises the following steps:

[0005] A phosphorene layer was prepared on the (111) crystal plane of the Au substrate;

[0006] Then, a diamond film is prepared on the phosphorene layer, and the product is taken out after cooling, so that the phosphorene layer in the product is degraded, and the Au substrate is peeled off to obtain a self-supporting diamond film.

[0007] In one embodiment, after the step of preparing a diamond film on the phosphorene layer is completed, cooling is performed at a speed of 1K / min-5K / min.

[0008] In one embodiment, before preparing the phosphorene layer on the (111) crystal plane of the Au substrate, the (111) crystal plane of the Au substrate is first argon ion etched, with an argon gas pressure of 0.001Pa-0.003Pa, an energy of 1keV-3keV, and an etching time of 10min-15min.

[0009] In one embodiment, a phosphorus atomic layer is prepared on the (111) crystal plane of the Au substrate by molecular beam epitaxy, and then the phosphorene layer is obtained by annealing under vacuum conditions.

[0010] In one embodiment, the thickness of the phosphorus atom layer is 0.3 mm-1 mm.

[0011] In one embodiment, in the step of preparing a phosphorus atomic layer on the (111) crystal plane of the Au substrate by molecular beam epitaxy, the phosphorus source is heated to 200° C.-300° C. by a beam source furnace, the temperature of the (111) crystal plane of the Au substrate is 330K-400K, and the deposition time is 5 min-10 min;

[0012] And / or, in the annealing step, the temperature is first raised to 450K-500K and kept for 10min-20min, and then dropped to room temperature at a speed of 5K / min-15K / min.

[0013] In one embodiment, the phosphorus source is selected from red phosphorus.

[0014] In one embodiment, a diamond film is formed on the phosphorene layer by microwave CVD method.

[0015] In one embodiment, in the step of preparing a diamond film on the phosphorene layer by microwave CVD method, deposition is first performed under a first condition and then under a second condition. Under the first condition, the carbon source ratio is 8%-10%, the deposition pressure is 0.5KPa-1KPa, and the microwave power is 2700W-2900W. Under the second condition, the carbon source ratio is 4%-7%, the deposition pressure is 1.5KPa-3KPa, and the microwave power is 3400W-5000W.

[0016] In one embodiment, the carbon source is selected from at least one of methane and acetylene;

[0017] And / or, the deposition time under the first condition is 20 min-40 min;

[0018] And / or, the deposition time under the second condition is more than 12 hours;

[0019] And / or, the thickness of the diamond film is greater than or equal to 100 μm.

[0020] In the preparation method of the present invention, since Au has excellent ductility and diamond is very hard, during the cooling process, the Au substrate can use its own ductility to slowly release the contraction stress on the diamond film, which can ensure that the diamond film will not break, and the obtained diamond film has almost no stress, and there is no need to perform a stress relief step, which can simplify the subsequent steps; at the same time, since Au is soft, the Au substrate will be broken during the cooling process, leaking the phosphorene layer, and the phosphorene can be naturally degraded in the atmospheric environment. Then, after the product is taken out, the phosphorene layer will react with water, oxygen, etc. in the atmospheric environment and degrade, and finally the Au substrate will be automatically peeled off to obtain a self-supporting diamond film, and there is no need to use concentrated nitric acid and hydrofluoric acid. It is not only safe and environmentally friendly, but also quick and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 Schematic diagram of the process flow of preparing the self-supporting diamond film of the present invention, wherein 10 is an Au substrate, 20 is a phosphorene layer, and 30 is a diamond film;

[0023] Figure 2 This is a confocal Raman spectrum of the self-supporting diamond film obtained in Example 1;

[0024] Figure 3 This is a confocal Raman spectrum of the self-supporting diamond film obtained in Example 2;

[0025] Figure 4 This is the confocal Raman spectrum of the self-supporting diamond film obtained in Comparative Example 2. DETAILED DESCRIPTION

[0026] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0028] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0029] like Figure 1 As shown, the method for preparing a self-supporting diamond film provided by the present invention comprises the following steps:

[0030] S1, preparing a phosphorene layer 20 on the (111) crystal plane of the Au substrate 10;

[0031] S2, then preparing a diamond film 30 on the phosphorene layer 20, taking out the product after cooling, degrading the phosphorene layer 20 in the product, and peeling off the Au substrate 10 to obtain a self-supporting diamond film 30.

[0032] Since phosphorene can be naturally degraded in the atmospheric environment and phosphorene has a lattice match with diamond, the present invention utilizes the phosphorene layer 20 as a transition layer, first grows the diamond film 30 on the phosphorene layer 20, and then utilizes the natural degradation ability of phosphorene to assist in the peeling of the diamond film 30 from the substrate, thereby being able to obtain a self-supporting diamond film 30 in a simpler way.

[0033] At present, phosphorene can be grown on the (111) crystal plane of the Au substrate and the (111) crystal plane of CuO. However, when using the phosphorene layer 20 to assist the diamond film 30 to be peeled off from the substrate, the ductility and softness of the substrate need to be considered, and the lattice matching degree between the substrate and the diamond also needs to be considered. Since Au has excellent ductility and softness, the present invention selects Au as the substrate, first prepares the phosphorene layer 20 on the (111) crystal plane of the Au substrate 10, and then prepares the diamond film 30 on the phosphorene layer 20, and finally utilizes the natural degradation ability of phosphorene to assist the peeling to obtain a self-supporting diamond film 30.

[0034] Specifically, since Au has excellent ductility and diamond is very hard, during the cooling process, the Au substrate 10 can use its own ductility to slowly release the contraction stress on the diamond film 30, thereby ensuring that the diamond film 30 will not break. At the same time, since the force is mutual, the expansion stress of the diamond film 30 will also be released along with the release of the contraction stress, so the obtained diamond film 30 has almost no stress, and there is no need to perform a stress relief step, which can simplify the subsequent steps.

[0035] In addition, since Au is soft, in the preparation method of the present invention, the Au substrate 10 will crack during the cooling process, leaking the phosphorene layer 20, and phosphorene can naturally degrade in the atmospheric environment. Then, after the product is taken out, the phosphorene layer 20 will react with water, oxygen, etc. in the atmospheric environment and degrade, and finally the Au substrate 10 will be automatically peeled off to obtain a self-supporting diamond film 30. There is no need to use concentrated nitric acid and hydrofluoric acid, which is not only safe and environmentally friendly, but also quick and convenient.

[0036] It should be noted that phosphorene is a general term for two-dimensional phosphorus elements, including blue phosphorus, black phosphorus, green phosphorus and purple phosphorus, all of which are layered phosphorus with different atomic arrangements. Accordingly, the phosphorene layer 20 can be a blue phosphorus layer, a black phosphorus layer, a green phosphorus layer and a purple phosphorus layer, etc.

[0037] In step S1, before preparing the phosphorene layer 20 on the (111) crystal plane of the Au substrate 10, it is preferred to first perform argon ion etching on the (111) crystal plane of the Au substrate 10 to remove surface impurities, obtain a clean (111) crystal plane, and make the (111) crystal plane atomically flat, which is conducive to the subsequent acquisition of layered phosphorene rather than obtaining three-dimensional structures of red phosphorus, white phosphorus, etc.

[0038] Optionally, in the argon ion etching step, the argon gas pressure is preferably 0.001Pa-0.003Pa, for example, 0.001Pa, 0.002Pa, 0.003Pa, etc., the energy is preferably 1keV-3keV, for example, 1keV, 1.5keV, 2keV, 2.5keV, 3keV, etc., and the etching time is preferably 10min-15min, for example, 10min, 11min, 12min, 13min, 14min, 15min, etc., or a range consisting of any two of these values.

[0039] In actual operation, only the (111) crystal plane of the Au substrate 10 may be etched with argon ions, or the entire Au substrate 10 may be etched with argon ions, which is not limited in the present invention.

[0040] There are many ways to prepare the phosphorene layer 20 on the (111) crystal plane of the Au substrate 10, and the present invention is not limited thereto. Preferably, in step S1 of the present invention, a phosphorus atomic layer is first prepared on the (111) crystal plane of the Au substrate 10 by molecular beam epitaxy, and then annealed under vacuum conditions so that the phosphorus atoms form a lattice structure to obtain the phosphorene layer 20.

[0041] Among them, the thickness of the phosphorus atomic layer is preferably 0.3mm-1mm, for example, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc., or a range composed of any two of these values. By choosing this, the obtained phosphorene layer 20 can not only play a supporting role, but also facilitate stress release.

[0042] In the step of preparing a phosphorus atomic layer on the (111) crystal plane of the Au substrate 10 by molecular beam epitaxy, the phosphorus source is preferably heated to 200°C-300°C in a beam source furnace, for example, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, etc. The temperature of the (111) crystal plane of the Au substrate 10 is preferably controlled at 330K-400K, for example, 330K, 340K, 350K, 360K, 370K, 380K, 390K, 400K, etc. The deposition time is preferably 5min-10min, for example, 5min, 6min, 7min, 8min, 9min, 10min, etc., or a range consisting of any two of these values, so that a phosphorus atomic layer of the desired thickness is obtained by adjusting the process conditions.

[0043] Wherein, the phosphorus source is selected from red phosphorus.

[0044] After a phosphorus atomic layer is prepared on the (111) crystal plane of the Au substrate 10 by molecular beam epitaxy, the Au substrate 10 with the phosphorus atomic layer is transferred to an annealing chamber in a vacuum interconnection system for annealing. Optionally, in the annealing step, the temperature is first raised to 450K-500K and kept warm for 10min-20min, for example, first raised to 450K, 460K, 470K, 480K, 490K, 500K, etc., and kept warm for 10min, 11min, 12min, The temperature is preferably 100 °C, 150 °C, 200 °C, 300 °C, 400 °F, 800 °C, etc., and then cooled to room temperature at a rate of 5 K / min-15 K / min, for example 5 K / min, 6 K / min, 7 K / min, 8 K / min, 9 K / min, 10 K / min, 11 K / min, 12 K / min, 13 K / min, 14 K / min, 15 K / min, etc., or a range consisting of any two of these values.

[0045] In step S2, there are many methods for preparing the diamond film 30 on the phosphorene layer 20, such as a high temperature and high pressure method, a DC plasma jet method, a hot wire CVD method, a microwave CVD method, etc., and the present invention is not limited thereto. Preferably, after the phosphorene layer 20 is prepared, the Au substrate 10 with the phosphorene layer 20 is transferred to a microwave CVD device in a vacuum interconnection system, and a diamond film 30 is prepared on the phosphorene layer 20 by a microwave CVD method.

[0046] Since the phosphorene layer 20 is relatively fragile and its lattice is somewhat different from that of diamond, when the diamond film 30 is prepared by microwave CVD, the diamond film 30 is first deposited under the first condition and then under the second condition. Under the first condition, the carbon source ratio is preferably 8%-10%, such as 8%, 9%, 10%, etc., the deposition pressure is preferably 0.5 KPa-1 KPa, such as 0.5 KPa, 0.6 KPa, 0.7 KPa, 0.8 KPa, 0.9 KPa, 1.0 KPa, etc., and the microwave power is preferably 2700 W-2900 W, such as 2700 W, 2750 W, 2800 W, 2850 W, 2900 W, etc. Under the second condition, the carbon source ratio is preferably 4%-7%, such as 4%, 5%, 6%, 7%, etc., and the deposition pressure is preferably 1.5 KPa-3 KPa, such as 1. W, 4200W, 4300W, 4400W, 4500W, 4600W, 4700W, 4800W, 4900W, 5000W, etc., or a range consisting of any two of these values, thereby, by sequentially depositing under two different conditions, a high quality diamond film 30 can be obtained.

[0047] The choice of carbon source is not limited, and is preferably at least one of methane and acetylene. It can be understood that the ratio of the carbon source refers to the ratio of the carbon source to hydrogen.

[0048] In the step of preparing the diamond film 30 on the phosphorene layer 20 by microwave CVD method, the deposition time under the first condition is preferably 20min-40min, for example, 20min, 25min, 30min, 35min, 40min, etc., and the deposition time under the second condition is preferably more than 12h, for example, 12h, 12.5h, 13h, 13.5h, 14h, etc., or a range consisting of any two of these values, so that a diamond film 30 with a thickness greater than or equal to 100μm can be obtained, which has better self-supporting properties after stripping off the Au substrate.

[0049] After the diamond film 30 is prepared by the microwave CVD method, the obtained product is a three-layer structure of the Au substrate 10, the phosphorene layer 20 and the diamond film 30 stacked in sequence. At this time, the temperature of the product is relatively high. In order to avoid the direct breakage of the diamond film 30, the microwave CVD equipment is first turned off to cool the product. During the cooling process, not only the stress can be gradually released to ensure that the diamond film will not break, but also the Au substrate 10 will crack and leak the phosphorene layer 20. Then, after the product is taken out, in the atmospheric environment, the phosphorene layer 20 in the product will react with water, oxygen and other substances in the air and degrade, and finally the Au substrate 10 will be peeled off to obtain a self-supporting diamond film 30.

[0050] During the cooling process of the product, it can be allowed to cool naturally to slowly release the stress. Preferably, cooling at a speed of 1K / min-5K / min can make the stress release process better.

[0051] Hereinafter, the method for preparing the self-supporting diamond film will be further described through the following specific examples.

[0052] Example 1

[0053] The Au substrate was etched with argon ions to remove impurities on the surface and obtain a clean (111) crystal plane, wherein the argon ion etching time was 10 minutes, the argon gas pressure was 0.003 Pa, and the energy was 3 keV.

[0054] A 0.5 mm thick phosphorus atomic layer was prepared on the (111) crystal plane of the Au substrate by molecular beam epitaxy, wherein red phosphorus was used as the phosphorus source and heated to 200°C in a beam source furnace. The temperature of the (111) crystal plane of the Au substrate was 400K and the deposition time was 5 minutes.

[0055] The Au substrate with the phosphorus atomic layer is transferred to the annealing chamber in a vacuum interconnection system, the vacuum degree of the annealing chamber is evacuated to below 0.001 Pa, and then the temperature is raised to 450K and kept for 15 minutes, and then dropped to room temperature at a rate of 5K / min to obtain a phosphorene layer uniformly covering the (111) crystal surface of the Au substrate.

[0056] The Au substrate with the phosphorene layer was transferred to the microwave CVD equipment in the vacuum interconnection system. Methane was used as the carbon source. The carbon source ratio was first set to 8%, the deposition pressure was 0.5 KPa, the microwave power was 2700 W, and the deposition was performed for 30 minutes. Then the carbon source ratio was set to 4%, the deposition pressure was 1.5 KPa, the microwave power was 3400 W, and the deposition was performed for 12 hours to obtain a three-layer structure of diamond film-phosphorene layer-Au substrate.

[0057] Turn off the microwave CVD equipment, cool naturally to room temperature, and then take out the product. In the atmospheric environment, the phosphorene layer in the three-layer structure of diamond film-phosphorene layer-Au substrate will react with water, oxygen and other substances in the air and degrade. Finally, the Au substrate will be peeled off to obtain a self-supporting diamond film with a thickness of 120μm.

[0058] Example 2

[0059] The Au substrate was etched with argon ions to remove impurities on the surface and obtain a clean (111) crystal plane, wherein the argon ion etching time was 15 minutes, the argon gas pressure was 0.003 Pa, and the energy was 1 keV.

[0060] A 1 mm thick phosphorus atomic layer was prepared on the (111) crystal plane of the Au substrate by molecular beam epitaxy, wherein red phosphorus was used as the phosphorus source and heated to 300°C in a beam source furnace. The temperature of the (111) crystal plane of the Au substrate was 400K and the deposition time was 10 minutes.

[0061] The Au substrate with the phosphorus atomic layer is transferred to the annealing chamber in a vacuum interconnection system, the vacuum degree of the annealing chamber is evacuated to below 0.001 Pa, and then the temperature is raised to 500 K and kept for 15 minutes, and then cooled to room temperature at a rate of 15 K / min to obtain a phosphorene layer uniformly covering the (111) crystal surface of the Au substrate.

[0062] The Au substrate with the phosphorene layer was transferred to the microwave CVD equipment in a vacuum interconnected system. Acetylene was used as the carbon source. The carbon source ratio was first set to 10%, the deposition pressure was 1 KPa, the microwave power was 2900 W, and the deposition was performed for 30 minutes. Then, the carbon source ratio was set to 7%, the deposition pressure was 3 KPa, and the microwave power was 3500 W. A diamond film was deposited on the phosphorene layer for 15 hours to obtain a three-layer structure of diamond film-phosphorene layer-Au substrate.

[0063] Turn off the microwave CVD equipment, cool to room temperature at a rate of 3K / min, and then take out the product. In the atmospheric environment, the phosphorene layer in the three-layer structure of diamond film-phosphorene layer-Au substrate will react with water, oxygen and other substances in the air and degrade. Finally, the Au substrate will be peeled off to obtain a self-supporting diamond film with a thickness of 150μm.

[0064] Raman spectroscopy is an important means of characterizing materials. Different substances have different Raman shift characteristic peak shifts. The Raman characteristic peak of diamond is 1332cm -1 The peak intensity represents the content of the substance, the peak width represents the crystal quality, and the blue shift and red shift of the peak represent the stress in the diamond film. Figure 2 and Figure 3 It can be seen that, firstly, the samples prepared in Example 1 and Example 2 have a -1 There are obvious characteristic peaks at all locations, the peak intensity is very high and 1000-2000cm -1 There are no other obvious characteristic peaks of the same intensity within the range, indicating that the main substance in the sample is diamond and the content is very high. Secondly, the half-peak width is very narrow, indicating that the sample has good crystal quality. Thirdly, the characteristic peak does not undergo redshift or blueshift, indicating that there is almost no stress inside the diamond film prepared by the method of the present invention.

[0065] Comparative Example 1

[0066] The Cu substrate is etched with argon ions to remove impurities on the surface and obtain a clean Cu (111) crystal surface, wherein the argon ion etching time is 10 minutes, the argon gas pressure is 0.003 Pa, and the energy is 3 keV.

[0067] The Cu substrate is oxidized to obtain Cu 2 O substrate.

[0068] Using molecular beam epitaxy on Cu 2 A 0.5 mm thick phosphorus atomic layer was prepared on the (111) crystal plane of an O substrate, wherein red phosphorus was used as the phosphorus source and heated to 200°C in a beam source furnace. 2 The temperature of the (111) crystal plane of the O substrate was 400 K, and the deposition time was 5 min.

[0069] The Cu with phosphorus atomic layer 2 The O substrate was transferred to the annealing chamber in the vacuum interconnection system, and the vacuum degree of the annealing chamber was evacuated to below 0.001 Pa. The temperature was then raised to 450 K and kept for 15 min, and then cooled to room temperature at a rate of 5 K / min to obtain a uniform coating on the Cu 2 Phosphorene layer on (111) O substrate.

[0070] The Cu with phosphorene layer 2The O substrate was transferred to the microwave CVD device in the vacuum interconnection system. Methane was used as the carbon source. The carbon source ratio was first set to 8%, the deposition pressure was 0.5 KPa, the microwave power was 2700 W, and the deposition was performed for 30 min. Then the carbon source ratio was set to 4%, the deposition pressure was 1.5 KPa, and the microwave power was 3400 W. Diamond film was deposited on the phosphorene layer for 12 h to obtain a diamond film-phosphorene layer-Cu 2 The product of the three-layer structure of O substrate.

[0071] The microwave CVD equipment was turned off, and the product was naturally cooled to room temperature. The diamond film was then taken out and cracked.

[0072] Comparative Example 2

[0073] The Au substrate was etched with argon ions to remove impurities on the surface and obtain a clean (111) crystal plane, wherein the argon ion etching time was 10 minutes, the argon gas pressure was 0.003 Pa, and the energy was 3 keV.

[0074] A 0.5 mm thick phosphorus atomic layer was prepared on the (111) crystal plane of the Au substrate by molecular beam epitaxy, wherein red phosphorus was used as the phosphorus source and heated to 200°C in a beam source furnace, while C60 was used as the doping source and heated to 300°C in a boron nitride crucible. The temperature of the (111) crystal plane of the Au substrate was 400K and the deposition time was 5 minutes.

[0075] The Au substrate with the phosphorus atomic layer is transferred to the annealing chamber in a vacuum interconnection system, the vacuum degree of the annealing chamber is evacuated to below 0.001 Pa, and then the temperature is raised to 450K and kept for 15 minutes, and then cooled to room temperature at a rate of 5K / min to obtain a defective phosphorene layer uniformly covering the (111) crystal surface of the Au substrate.

[0076] The Au substrate with the phosphorene layer was transferred to the microwave CVD equipment in the vacuum interconnection system. Methane was used as the carbon source. The carbon source ratio was first set to 8%, the deposition pressure was 0.5 KPa, the microwave power was 2700 W, and the deposition was performed for 30 minutes. Then the carbon source ratio was set to 4%, the deposition pressure was 1.5 KPa, and the microwave power was 3400 W. A diamond film was deposited on the phosphorene layer for 12 hours to obtain a three-layer structure of diamond film-phosphorene layer-Au substrate.

[0077] Turn off the microwave CVD equipment, cool naturally to room temperature, and then take out the product. In the atmospheric environment, the phosphorene layer in the three-layer structure of diamond film-phosphorene layer-Au substrate will react with water, oxygen and other substances in the air and degrade. Finally, the Au substrate will be peeled off to obtain a self-supporting diamond film with a thickness of 97 microns.

[0078] The Raman test results of the diamond film obtained in this comparative example are as follows: Figure 4 As shown, at the characteristic diamond peak of 1332 cm -1 The peak intensity is not as good as that of Example 1 and Example 2, indicating that the total amount of diamond material in this comparative example is not as good as that of Example 1 and Example 2, and the half peak width is wider, indicating that the crystal quality is not as good as that of Example 1 and Example 2. In addition, at 1430cm -1 -1600cm -1 There is an obvious hump in the range, which is polyacetylene and sp 2 The characteristic peaks of graphitic carbon indicate that defects in phosphorene will affect the quality of the diamond film.

[0079] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a self-supporting diamond film, characterized in that: The following steps are involved: A phosphorene layer was prepared on the (111) crystal plane of the Au substrate; The Au substrate with the phosphorene layer is transferred using a vacuum interconnection system, and a diamond film is prepared. The product is then cooled. During the cooling process, it is ensured that the diamond film does not break. The Au substrate is cracked to leak out the phosphorene layer. The product is then taken out, the phosphorene layer in the product is degraded, and the Au substrate is peeled off to obtain a self-supporting diamond film.

2. The method for preparing a self-supporting diamond film according to claim 1, characterized in that: After the step of preparing the diamond film on the phosphorene layer is completed, cooling is performed at a speed of 1 K / min-5 K / min.

3. The method for preparing a self-supporting diamond film according to claim 1, characterized in that: Before preparing the phosphorene layer on the (111) crystal plane of the Au substrate, the (111) crystal plane of the Au substrate is first etched by argon ions, with an argon pressure of 0.001 Pa-0.003 Pa, an energy of 1 keV-3 keV, and an etching time of 10 min-15 min.

4. The method for preparing a self-supporting diamond film according to claim 1, characterized in that: A phosphorus atomic layer is prepared on the (111) crystal plane of the Au substrate by molecular beam epitaxy, and then a phosphorene layer is obtained by annealing under vacuum conditions.

5. The method for preparing a self-supporting diamond film according to claim 4, characterized in that: The thickness of the phosphorus atomic layer is 0.3 mm-1 mm.

6. The method for preparing a self-supporting diamond film according to claim 4, characterized in that: In the step of preparing a phosphorus atomic layer on the (111) crystal plane of the Au substrate by molecular beam epitaxy, the phosphorus source is heated to 200° C.-300° C. by a beam source furnace, and the temperature of the (111) crystal plane of the Au substrate is 330K-400K; And / or, in the annealing step, the temperature is first raised to 450K-500K and kept for 10min-20min, and then dropped to room temperature at a speed of 5K / min-15K / min.

7. The method for preparing a self-supporting diamond film according to claim 6, characterized in that: The phosphorus source is selected from red phosphorus.

8. The method for preparing a self-supporting diamond film according to claim 1, characterized in that: A diamond film is prepared on the phosphorene layer by using a microwave CVD method.

9. The method for preparing a self-supporting diamond film according to claim 8, characterized in that: In the step of preparing a diamond film on the phosphorene layer by microwave CVD, deposition is first performed under a first condition and then under a second condition. Under the first condition, the carbon source ratio is 8%-10%, the deposition pressure is 0.5KPa-1KPa, and the microwave power is 2700W-2900W. Under the second condition, the carbon source ratio is 4%-7%, the deposition pressure is 1.5KPa-3KPa, and the microwave power is 3400W-5000W.

10. The method for preparing a self-supporting diamond film according to claim 9, characterized in that: The carbon source is selected from at least one of methane and acetylene; And / or, the deposition time under the first condition is 20 min-40 min; And / or, the deposition time under the second condition is more than 12 hours; And / or, the thickness of the diamond film is greater than or equal to 100 μm.

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