Porous flexible gallium nitride with large depth-to-width ratio and preparation method and application thereof

Abstract

The invention discloses porous flexible gallium nitride with a large depth-to-width ratio and a preparation method and application thereof, and belongs to the technical field of semiconductor material processing. Adding metal salt into the phosphoric acid solution, and dissolving to form a phosphoric acid-metal salt composite corrosion system solution; and heating the phosphoric acid-metal salt composite corrosion system solution, heating to a certain temperature, adding a GaN sample, reacting for a period of time, taking out, washing and drying to obtain the porous flexible gallium nitride with the large depth-to-width ratio. The method has the characteristics of stable reaction temperature and instantaneous termination of the reaction, can inhibit the radial corrosion rate and promote the axial corrosion rate, can accurately and effectively prepare the porous flexible gallium nitride with the large depth-to-width ratio, can be used for subsequent single crystal growth and device preparation, and is high in controllability, good in economical efficiency and suitable for large-scale production and application.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material processing technology, specifically relating to a high aspect ratio porous flexible gallium nitride, its preparation method, and its application. Background Technology

[0002] GaN, with its wide bandgap, high breakdown field strength, and excellent thermal conductivity, has become a key material foundation for breaking through the performance limits of traditional silicon-based semiconductors and supporting next-generation information technology, high-end manufacturing, and green energy transformation. GaN power electronic devices have achieved initial commercialization in fields such as fast charging and signal base stations. However, these high-performance devices are currently mainly based on heteroepitaxies of sapphire, SiC, or Si, with high-density dislocations (10⁻⁶). 6 -10 10 cm -2 The high density of dislocations and residual stress within GaN crystals severely restricts device reliability and lifespan. Developing GaN with flexible structures can effectively reduce dislocation density and residual stress within the crystal. A report by the Semiconductor Equipment and Materials International (SEMI) shows that the global semiconductor materials market reached $630.5 billion in 2024, a year-on-year increase of 19.7%. International Data Corporation (IDC) further points out that emerging fields such as artificial intelligence will continue to drive strong growth in the global semiconductor market, placing even higher demands on the fabrication of flexible GaN.

[0003] Currently, traditional methods for preparing flexible substrates all have their own shortcomings and cannot meet current application requirements. For example, magnetron sputtering introduces impurities into the crystal surface, affecting subsequent GaN crystal growth, and the related equipment is relatively expensive and difficult to maintain; mixed alkali etching requires not only 350℃ to obtain molten alkali, but also a large amount of mixed alkali, which easily absorbs carbon dioxide from the air and loses its corrosive activity, often requiring cleaning and replacement after only a few uses, resulting in high costs and many hidden dangers; high-temperature ablation results in too many uncontrollable factors and poor repeatability in the preparation of flexible substrates; electrochemical etching requires the material to have ideal conductivity, and is naturally limited to n-type doped conductive GaN, making it difficult to extend to other materials; phosphoric acid etching is the most widely used and convenient method for preparing porous flexible substrates, but in addition to being affected by the hexagonal wurtzite structure of GaN material, phosphoric acid itself has high viscosity, which affects the rate at which it diffuses into the material through the pores, making it difficult to obtain porous flexible substrates with deep pore diameters. This means that it is extremely difficult to prepare porous flexible GaN with a large aspect ratio in phosphoric acid etching solution. Summary of the Invention

[0004] To address the problems of high cost, complex operation, easy introduction of impurities, and poor preparation and use of porous flexible GaN in existing technologies, this invention provides a high aspect ratio porous flexible gallium nitride, its preparation method, and its application. It features stable reaction temperature and instantaneous reaction termination, and can suppress radial corrosion rate while promoting axial corrosion rate. This allows for the precise and effective preparation of high aspect ratio porous flexible gallium nitride, which can be used for subsequent single crystal growth and device fabrication. It offers strong controllability, good economic efficiency, and is suitable for large-scale production applications.

[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for fabricating a porous flexible gallium nitride with a large aspect ratio, comprising the following steps: (1) Adding a metal salt to a phosphoric acid solution and dissolving it forms a phosphoric acid-metal salt composite corrosion system solution; (2) Assemble a special constant temperature corrosion heating experimental device; (3) The phosphate-metal salt composite corrosion system solution in heating step (1) is added to a special constant temperature corrosion heating experimental device. After heating to a certain temperature, GaN sample is added. After reacting for a period of time, it is taken out, washed, and dried to obtain a high aspect ratio porous flexible gallium nitride.

[0006] Further, the mass percentage concentration of the phosphoric acid solution in step (1) is 50-85%; the metal salt contains the cation Fe. 3+ Fe 2+ Cu 2+ Al 3+ and Ag + It is one or more of a soluble chloride, nitrate or sulfate salt; the concentration of the metal salt is 0.1~1 mol / L.

[0007] Furthermore, in step (2), the phosphate-metal salt composite corrosion system solution is heated to 200~350℃ and then GaN sample is added, and the reaction time is 15~120min.

[0008] Furthermore, the GaN sample described in step (2) is horizontally suspended in a phosphate-metal salt composite corrosion system solution.

[0009] Furthermore, the GaN sample is one of the following: undoped GaN crystal, n-type GaN crystal, p-type GaN crystal, MOCVD-grown sapphire-based GaN epitaxial wafer, silicon carbide-based GaN epitaxial wafer, and silicon-based epitaxial wafer.

[0010] Furthermore, the dedicated constant temperature corrosion heating experimental device includes a constant temperature heating stage, a large outer diameter glass vessel a, a medium outer diameter glass vessel b, a small outer diameter glass vessel c, an iron frame with multiple iron clamps, and binding ropes. The large-diameter glass vessel a is placed on a constant-temperature heating platform, the medium-diameter glass vessel b is suspended in the large-diameter glass vessel a by iron clamps and binding ropes, and the small-diameter glass vessel c is suspended in the medium-diameter glass vessel b by iron clamps and binding ropes. The bottom glass of the small-diameter glass vessel c has multiple holes.

[0011] Furthermore, the large-diameter glass vessel a contains silicone oil, and the bottom of the medium-diameter glass vessel b is immersed in the silicone oil for heating the liquid in the medium-diameter glass vessel b; the medium-diameter glass vessel b is used to hold the phosphate-metal salt composite corrosion system solution, and the bottom of the small-diameter glass vessel c is immersed in the phosphate-metal salt composite corrosion system solution; the GaN sample is placed at the bottom of the small-diameter glass vessel c, and the GaN sample is immersed in the phosphate-metal salt composite corrosion system solution.

[0012] Furthermore, the dedicated constant-temperature corrosion heating experimental apparatus is equipped with a thermometer, which is suspended in a glass container b with an inner and outer diameter by an iron clamp and a binding rope, indicating the temperature of the solution in the glass container b. The thermometer can be selected to measure temperatures from 300 to 1200 ℃, and can be any one of the seven standardized thermocouples (S, B, E, K, R, J, T) as the temperature indicating device.

[0013] In a second aspect, the present invention discloses the prepared high aspect ratio porous flexible gallium nitride, characterized in that the aspect ratio of the high aspect ratio porous flexible gallium nitride is greater than 5:1.

[0014] In a third aspect, the present invention discloses the application of the high aspect ratio porous flexible gallium nitride in the preparation of semiconductor materials; the porous flexible GaN can be used as a substrate for GaN single crystal growth, or as a substrate for the preparation of GaN-based related devices.

[0015] Gallium nitride (GaN) crystals have a passivation layer on their surface consisting of a thin layer of gallium oxide formed by oxidation and an adsorbed gas layer. During immersion in liquid, the corrosive liquid does not directly contact the GaN crystal, and the corresponding corrosion reaction does not occur rapidly. According to crystal dislocation theory, dislocations within a GaN crystal can only be annihilated or exposed at dislocation sites. First, lattice distortion exists at dislocation sites, disrupting the stability of the passivation layer and exposing the internal GaN crystal. Second, dislocation sites also possess dislocation strain energy, consisting of dislocation nucleus energy and elastic strain energy. The dislocation nucleus energy is much smaller than the elastic strain energy; therefore, elastic strain energy is generally used to refer to dislocation strain energy. The elastic strain energy of a screw dislocation is... W s = (Gb 2 / 4π)lnR / r0, the elastic strain energy of the edge dislocation is W e = (Gb 2 / 4π(1-v))lnR / r 0, Mixed dislocation elastic strain energy W 混 = (Gb 2 / 4πK)lnR / r 0. Among them, r 0 represents the radius of the dislocation nucleus; R The radius of the area affected by the dislocation stress field; V It is Poisson's ratio (the Poisson's ratio of gallium nitride crystals is generally taken as 0.2); K The angle factor represents the decomposition of mixed dislocations, with a value of 1 for pure screw dislocations and 0.8 for pure edge dislocations. Based on these two reasons, the corrosion reaction preferentially occurs at dislocation sites. The chemical reaction equation between gallium nitride crystals and the etching liquid phase is as follows: Gallium nitride (GaN) dissolves at dislocation sites, forming corrosion channels. The newly exposed GaN crystal, through oxidation and gas adsorption, generates a new passivation layer, hindering the corrosion reaction. Simultaneously, GaPO4 produced by the corrosion reaction accumulates at the tip of the corrosion channel, blocking the dislocation line outcrop. GaPO4 is extremely stable, exhibiting excellent chemical inertness, and is insoluble in water, common acids (such as hydrochloric acid, nitric acid, and sulfuric acid), and organic solvents. It can only be slowly eroded by hydrofluoric acid or hot concentrated alkali. Due to the hindering effect of the passivation layer and GaPO4, as well as the influence of the GaN crystal structure, the corrosion reaction continues along the existing channels, widening the corrosion channels. The final result is that the corrosion pits formed by the reaction are often large in diameter, shallow in depth, and have a very small aspect ratio.

[0016] When gallium nitride crystals or thin films with small aspect ratios are used as porous flexible or buffer substrates, the following four unavoidable defects exist: First, due to the excessively large aperture of the etch pits and the excessively long step edges, too many nucleation sites are provided during crystal growth. After 3D island-mounted growth, this is not conducive to the merging of crystal nuclei, and it is easy to form cellular or mosaic structures, generating grain boundaries. Second, the excessively large aperture of the etch pits affects the balanced growth of two-dimensional lateral epitaxial layers, resulting in macroscopic defects. Third, shallower etch pits will be filled by subsequent growth, and the native dislocations in the flexible substrate will continue to be introduced into the newly grown crystal along with the crystal growth, failing to reduce dislocation density and improve crystal quality. Fourth, if the etch pits are too shallow, even if they are completely covered and filled by subsequent crystal growth, the buffer strain zone generated by the porous structure of the etch pits will be correspondingly smaller, weakening or failing the function of the flexible substrate in releasing residual stress. Especially during heteroepitaxial growth, in addition to thermal mismatch, there is also huge residual stress caused by lattice mismatch, which can easily lead to the fragmentation of the grown crystal.

[0017] Adding metal salts to the etching solution thermodynamically reduces the concentration of free target ions or alters their form, and kinetically accelerates them by influencing interfacial processes, thus driving the dissolution equilibrium to shift continuously to the right. The metal salt solution disrupts the passivation layer on the GaN crystal surface, primarily for the following reasons: (1) When a metal salt (excluding phosphate) is added to the corrosive solution, the metal salt ionizes to produce a large number of dissimilar ions, increasing the total ion concentration in the solution. This, in turn, strengthens the electrostatic interactions of the ionic bonds, leading to a decrease in the "effective concentration" or activity of the cations and anions. According to the thermodynamic formula, the solubility product constant Ksp = γ + (M) + )·γ - (A) - When the ionic strength increases, the activity coefficient γ + γ - When the concentration of ions decreases, in order to maintain the solubility product constant Ksp constant, the concentration of ions [M]... + ] and [A - The solubility must increase. More sparingly soluble substances need to dissolve to increase the analytical concentration of ions, thus increasing the solubility of the corrosion reaction product GaPO4. Some metal salts will also react with Ga... 3+ The formation of complexes promotes the dissolution of GaPO4.

[0018] (2) Under illumination, photogenerated electron-hole pairs (e-hole pairs) will be generated in GaN crystals. - and h + ), and h + During the corrosion process, exposed gallium atoms are activated, making them easier to corrode and dissolve. However, when h + When consumed in large quantities, the remaining e - Unable to be released, it can only seize the newly born h under the light. + Therefore, electron-hole recombination occurs, limiting the corrosion rate of GaN. Adding a metal salt, however, allows the positive ions generated by the ionization of the metal salt to act as efficient electron acceptors, rapidly capturing excess electrons. - Reduce e in the system - The concentration of electrons in the low-valence metal salt cations is adjusted, and the low-valence cations that gain electrons are then re-oxidized into high-valence cations by dissolved oxygen or other oxidants in the solution. This forms an efficient electron transfer mediator cycle that continuously consumes photogenerated electrons, promotes more holes for surface oxidation, and thus catalyzes the entire corrosion reaction of GaN.

[0019] (3) Metal salt cations often exhibit oxidizing properties when ionized in solution, such as Ag. +These elements undergo an electron transfer reaction on the GaN surface, capturing electrons from nitrogen (N) and being reduced and deposited as low-valence metallic elements, which then deposit as nanoparticles on the GaN surface. The deposited metal comes into contact with GaN, creating a "gold-semi-contact" relationship and forming numerous microscopic galvanic cells. In the etching solution, the metal acts as the cathode and GaN as the anode. Under the influence of these galvanic cells, charge transfer is accelerated, greatly increasing the corrosion rate of the anode GaN, resulting in a self-catalytic corrosion effect.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention utilizes a dedicated constant-temperature corrosion heating experimental device and a phosphate-metal salt composite corrosion system solution, which features stable reaction temperature and instantaneous reaction termination. It can also suppress radial corrosion rate and promote axial corrosion rate, enabling precise and effective preparation of porous flexible gallium nitride with a large aspect ratio. This solution can be used for subsequent single crystal growth and device fabrication, offering strong controllability, good economic efficiency, and suitability for large-scale production applications. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a dedicated constant-temperature corrosion heating experimental device designed and assembled independently; 1 is the heating platform, 2 is a glass vessel with a large outer diameter, 3 is a glass vessel with a medium outer diameter, 4 is a glass vessel with a small outer diameter, 5 is an iron stand, 6 is an iron clamp, 7 is a thermometer, and 8 is a binding rope. Figure 2 SEM surface morphology of the porous flexible gallium nitride with a large aspect ratio prepared in Example 1; Figure 3 SEM cross-sectional morphology of the porous flexible gallium nitride with a large aspect ratio prepared in Example 1; Figure 4 Image of GaN single crystal obtained after growth by HVPE method in Example 2; Figure 5 The image shows the Raman spectral density of the GaN single crystal obtained after growth by the HVPE method in Example 2. Figure 6 SEM surface morphology of the porous flexible gallium nitride with small aspect ratio prepared for Comparative Example 1; Figure 7 SEM cross-sectional morphology of the porous flexible gallium nitride with a small aspect ratio prepared for Comparative Example 1. Detailed Implementation

[0022] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods not specifically described in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. All reagents and materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0024] The present invention provides a dedicated isothermal etching heating experimental apparatus for preparing porous flexible gallium nitride with a large aspect ratio, as follows: Figure 1 As shown; by Figure 1 It is known that the dedicated constant-temperature corrosion heating experimental device includes a constant-temperature heating platform 1 (a constant-temperature heating platform with a platform size of 200*300mm, capable of heating to 400℃ (its platform is covered with aluminum foil to prevent drip corrosion)), a large-diameter glass vessel a 2 (outer diameter of 200 mm, depth of 99 mm, glass thickness of 3 mm), a medium-diameter glass vessel b 3 (outer diameter of 180 mm, depth of 90 mm, glass thickness of 3 mm, with four evenly spaced circular holes of 5 mm diameter on the outer edge of the top, suspended from the iron frame 5 by binding rope (graphite rope) 8 and fixed by iron clamp 6), and a small-diameter glass vessel c 4 (outer diameter of 150 mm, depth of 62 mm, glass thickness of 3 mm), with evenly spaced circular holes of 3 mm diameter on the bottom and four evenly spaced circular holes of 5 mm diameter on the outer edge of the top. The circular hole is mm in diameter, and is suspended from the iron frame 5 by a binding rope (graphite rope) 8 and fixed by iron clamps 6. The iron frame is equipped with multiple iron clamps. The large-diameter glass vessel a2 is placed on the heating platform 1. The medium-diameter glass vessel b3 is suspended inside the large-diameter glass vessel a2 by an iron frame with multiple iron clamps. The large-diameter glass vessel a2 contains silicone oil (1500 mL). The bottom of the medium-diameter glass vessel b3 is immersed in the silicone oil for heating the liquid in the medium-diameter glass vessel b3. The small-diameter glass vessel c4 is suspended inside the medium-diameter glass vessel b3 by an iron frame with multiple iron clamps. The medium-diameter glass vessel b3 is used to hold the phosphate-metal salt composite corrosion system solution. The bottom of the small-diameter glass vessel c4 is immersed in the phosphate-metal salt composite corrosion system solution. The bottom glass of the small-diameter glass vessel c 4 has multiple holes. The GaN sample is placed at the bottom of the small-diameter glass vessel c and immersed in the phosphate-metal salt composite corrosion system solution.

[0025] The iron frame 5, which is equipped with multiple iron clamps 6, is equipped with a thermometer 7, which is connected to the iron clamps 6 by a binding rope (graphite rope) 8. It is used to test the temperature of the phosphate-metal salt composite corrosion system solution. The thermometer has a maximum measuring temperature of 300 ℃ and a mercury thermometer can be selected as the temperature indicating device.

[0026] Using the aforementioned dedicated constant-temperature corrosion heating experimental apparatus, and in conjunction with specific embodiments, this application describes the high aspect ratio porous flexible gallium nitride and its preparation method.

[0027] Example 1 (1) According to Figure 1 Assemble a dedicated isothermal corrosion heating experimental apparatus for a porous flexible gallium nitride with a large aspect ratio. Add glycerol to a glass vessel a2 with a large outer diameter and add a phosphoric acid-metal salt composite corrosion system solution (Al2(SO4)3 added to 85% phosphoric acid by mass, and the concentration of the metal salt solution is 0.5 mol / L, as the corrosion solution) to a glass vessel b3 with a medium outer diameter. (2) The phosphoric acid solution in glass vessel b 3 with a medium outer diameter was heated to 300°C. The MOCVD-grown sapphire-based GaN epitaxial wafer was placed in glass vessel c 4 with a small outer diameter. After reacting for 30 min, it was removed and rinsed with deionized water. Then, it was ultrasonically cleaned in acetone, ethanol and deionized water in sequence to thoroughly remove residual corrosion products and salts on the surface. It was dried with nitrogen gas to obtain a porous flexible gallium nitride with a large aspect ratio, which is greater than 5:1. The SEM surface morphology and SEM cross-sectional morphology of the porous flexible gallium nitride with a large aspect ratio prepared in Example 1 are as follows. Figure 2 and Figure 3 As shown.

[0028] Example 2 In Example 3, the metal salt in step (1) of the phosphate-metal salt composite corrosion system solution is FeCl3 (0.5 mol / L), which is the same as the step in Example 1, to prepare a porous flexible gallium nitride with a large aspect ratio, greater than 5:1; using the prepared porous flexible gallium nitride with a large aspect ratio as a substrate, and using the GaN single crystal obtained after HVPE growth, a 4-inch GaN single crystal is obtained as shown in the figure. Figure 4 As shown, its Raman test results are as follows: Figure 5 As shown in the figure, the 4-inch GaN single crystal surface is smooth and free of macroscopic cracks. The Raman test results show that compared with the test results of crystals grown on untreated substrates, its E2 peak has a significant red shift, indicating that the residual stress is significantly reduced.

[0029] Example 3 In Example 3, step (2) is to prepare a GaN single crystal wafer, which is the same as the steps in Example 1. A porous flexible gallium nitride with a large aspect ratio of more than 5:1 is prepared.

[0030] Example 4 Example 4: The sample used was a GaN single crystal wafer, and the added metal salt was 0.5 mol / L FeCl3. The remaining steps were the same as in Example 2, and a porous flexible gallium nitride with a large aspect ratio of more than 5:1 was prepared.

[0031] Example 5 In Example 5, the reaction temperature was set at 240°C and the reaction time was 60 min. The remaining steps were the same as in Example 2, and a porous flexible gallium nitride with a large aspect ratio of more than 5:1 was prepared.

[0032] Example 6 In Example 6, the sample used was a GaN single crystal wafer. The reaction temperature was set to 240°C and the reaction time to 60 min. The remaining steps were the same as in Example 2. A porous flexible gallium nitride with a large aspect ratio of more than 5:1 was prepared.

[0033] Comparative Example 1 (1) According to Figure 1 A dedicated isothermal corrosion heating experimental apparatus for assembling a porous flexible gallium nitride with a large aspect ratio was used. Glycerin was added to a glass vessel a2 with a large outer diameter, and an 85% phosphoric acid solution was added to a glass vessel b3 with a medium outer diameter as the corrosion solution. (2) The phosphoric acid solution in glass vessel b with a medium outer diameter was heated to 300°C. The MOCVD-grown sapphire-based GaN epitaxial wafer was placed in glass vessel C with a small outer diameter. After reacting for 15 min, it was removed and rinsed with deionized water. Subsequently, it was ultrasonically cleaned in acetone, ethanol, and deionized water in sequence to thoroughly remove residual corrosion products and salts on the surface. It was then dried with nitrogen to obtain a porous flexible gallium nitride with a small aspect ratio (less than 3:1). The SEM surface morphology and SEM cross-sectional morphology of the prepared porous flexible gallium nitride with a small aspect ratio are shown below. Figure 6 and Figure 7 As shown.

Claims

1. A method for preparing a flexible gallium nitride having a large aspect ratio and a porous structure, comprising the steps of: It comprises the following steps: ​ (1) adding metal salt into phosphoric acid solution to form phosphoric acid-metal salt complex corrosion system solution after dissolution; (2) assembling special constant temperature corrosion heating experimental device; (3) heating the phosphoric acid-metal salt complex corrosion system solution in step (1) and adding into the special constant temperature corrosion heating experimental device, then adding GaN sample after heating to a certain temperature, taking out after reaction for a period of time, washing and drying to obtain large aspect ratio porous flexible gallium nitride.

2. The method for preparing a high aspect ratio porous flexible gallium nitride according to claim 1, characterized in that, The mass percentage concentration of the phosphoric acid solution in step (1) is 50-85%; the metal salt is one or more of soluble chloride, nitrate or sulfate salts containing cations Fe 3+ , Fe 2+ , Cu 2 + , Al 3+ and Ag + ; the concentration of the metal salt is 0.1-1 mol / L.

3. The method for preparing a porous flexible gallium nitride with a large aspect ratio according to claim 1, characterized in that, The phosphoric acid-metal salt complex corrosion system solution in step (2) is heated to 200-350℃ and then the GaN sample is added, and the reaction time is 15-120 min.

4. The method for preparing a porous flexible gallium nitride with a large aspect ratio according to claim 1, characterized in that, The GaN sample in step (2) is horizontally suspended in the phosphoric acid-metal salt complex corrosion system solution.

5. The method for preparing a porous flexible gallium nitride with a large aspect ratio according to claim 1, characterized in that, The GaN sample is one of non-doped GaN crystal, n-type GaN crystal, p-type GaN crystal, MOCVD grown sapphire-based GaN epitaxial wafer, silicon carbide-based GaN epitaxial wafer and silicon-based epitaxial wafer.

6. The preparation method of the large aspect ratio porous flexible gallium nitride according to claim 1, characterized in that, The special constant temperature corrosion heating experimental device comprises constant temperature heating table (1), large outer diameter glassware a (2), medium outer diameter glassware b (3), small outer diameter glassware c (4), iron stand (5) provided with multiple iron clamps (6) and binding rope (8); The large outer diameter glassware a (2) is placed on the constant temperature heating table (1), the medium outer diameter glassware b (3) is suspended in the large outer diameter glassware a (2) through the iron clamps (6) and the binding rope (8), and the small outer diameter glassware c (4) is suspended in the medium outer diameter glassware b (3) through the iron clamps (6) and the binding rope (8); Multiple holes are opened in the bottom glass of the small outer diameter glassware c (4).

7. The method of claim 6, wherein the method is performed at a temperature of 1000 °C or less. The large outer diameter glassware a (2) is filled with silicone oil, the medium outer diameter glassware b (3) is immersed in the silicone oil, and the liquid in the medium outer diameter glassware b (3) is heated; the medium outer diameter glassware b (3) is used for containing the phosphoric acid-metal salt complex corrosion system solution, the small outer diameter glassware c (4) is immersed in the phosphoric acid-metal salt complex corrosion system solution, the GaN sample is placed at the bottom of the small outer diameter glassware c (4), and the GaN sample is immersed in the phosphoric acid-metal salt complex corrosion system solution.

8. The method for preparing a porous flexible gallium nitride with a large aspect ratio according to claim 6, characterized in that, The special constant temperature corrosion heating experimental device is provided with a thermometer (7) suspended in the medium outer diameter glassware b (3) through the iron clamps (6) and the binding rope (8), and the temperature of the solution in the medium outer diameter glassware b (3).

9. The flexible GaN with high aspect ratio holes according to any one of claims 1 to 8, wherein the flexible GaN with high aspect ratio holes has a thickness of 1 to 1000 nm. The large aspect ratio porous flexible gallium nitride has an aspect ratio greater than 5:

1.

10. Application of the large aspect ratio porous flexible gallium nitride prepared according to any one of claims 1-8 or the large aspect ratio porous flexible gallium nitride according to claim 9 in preparation of semiconductor material.

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