Method for preparing monolayer nitride

Abstract

The application discloses a method for preparing monolayer nitride, comprising the following steps: providing a metal single crystal as a substrate; selecting a metal organic compound as an evaporation source, and adsorbing the metal organic compound on the surface of the metal single crystal; and heating the substrate to 350 DEG C-450 DEG C, so that the metal organic compound on the surface of the substrate is decomposed and surface in-situ chemical reaction occurs, and monolayer nitride is generated. The method for preparing monolayer nitride can realize controllable growth of monolayer nitride, and the grown monolayer nitride crystal has good crystallinity and high flatness, thereby laying a good foundation for preparation of high-integration nitride devices.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material growth technology, and in particular to a method for growing a monolayer nitride by in-situ chemical reaction on the surface of a metal-organic compound. Background Technology

[0002] Third-generation semiconductors have developed rapidly since the beginning of the 21st century, with nitride semiconductors being a star product. Compared to traditional silicon semiconductors, nitride semiconductors have many advantages, including high electron mobility, wide bandgap, high electron saturation drift velocity, and stability under high-energy electron beam irradiation and high-temperature environments. The wurtzite structure of nitride semiconductors is a direct bandgap semiconductor and is currently the mainstream material for new display devices, electronic power devices, solar inverters, communication equipment, and radar systems. However, III-V group nitrides have sp3 orbital hybridization, making them prone to longitudinal bonding during growth and difficult to obtain using traditional vapor-phase growth or mechanical exfoliation methods. Theoretical calculations show that when the atomic layers of nitride materials decrease by 5, the thermodynamic properties tend to stabilize, leading to phenomena such as an increase in lattice constant and a blue shift in the bandgap. Due to the ultrathin thickness of single-atom nitrides, they exhibit strong quantum confinement effects and visible light transmittance, which leads to some new electronic, optical, and phonon properties, such as modulation of the band structure, confinement of electron transport, enhancement of optical absorption, and blue shift of luminescence. These properties make them of great potential for application in optoelectronics, transparent electronic devices, and optoelectronic devices.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing single-atom-layer nitrides, which enables the controllable growth of single-atom-layer nitrides. The grown single-atom-layer nitride crystals have good crystallinity and are highly flat, laying a good foundation for the fabrication of highly integrated nitride devices.

[0005] To achieve the above objectives, embodiments of the present invention provide a method for preparing a single-atom-layer nitride, comprising: providing a metal single crystal as a substrate; selecting a metal-organic compound as an evaporation source and adsorbing it onto the surface of the metal single crystal; heating the substrate to 350°C-450°C, wherein the metal-organic compound on the substrate surface decomposes and undergoes an in-situ surface chemical reaction to generate a single-atom-layer nitride.

[0006] In one or more embodiments of the present invention, the organometallic compound includes one or more of trimethylaminogallium, trimethylaminoindium, and trimethylaminoaluminum.

[0007] In one or more embodiments of the present invention, the metal single crystal includes one of Au, Ag, and Cu.

[0008] In one or more embodiments of the present invention, before the step of adsorbing the metal-organic material onto the surface of the metal single crystal, the method further includes the steps of cleaning, degassing and annealing the metal single crystal.

[0009] In one or more embodiments of the present invention, the step of cleaning a metal single crystal includes: immersing the metal single crystal in an organic solvent and subjecting it to ultrasonic treatment to remove organic matter from the surface of the metal single crystal; immersing the metal single crystal in deionized water or pure water and adding a reducing agent to remove oxides from the surface of the metal single crystal; immersing the metal single crystal in an acidic solution to remove residual oxides and impurities from the surface of the metal single crystal; immersing the metal single crystal in an alkaline solution to neutralize acidic substances on the surface of the metal single crystal and cleaning the surface of the metal single crystal; immersing the metal single crystal in deionized water or pure water for surface rinsing; and drying the metal single crystal with nitrogen or under vacuum.

[0010] In one or more embodiments of the present invention, the organic solvent includes ethanol and acetone.

[0011] In one or more embodiments of the present invention, the reducing agent includes hydrofluoric acid and ferrous chloride.

[0012] In one or more embodiments of the present invention, the acidic solution includes nitric acid and sulfuric acid.

[0013] In one or more embodiments of the present invention, the alkaline solution includes sodium hydroxide and ammonia.

[0014] In one or more embodiments of the present invention, the steps of degassing and annealing the metal single crystal include: bombarding the surface of the metal single crystal with argon ions with an energy of 0.7-1.5 eV for 15-20 min; heating the metal single crystal to 700-800°C at a rate of 10-15°C / min; cooling it to 380-400°C at a rate of 10-15°C / min; and holding it at that temperature for 18-22 min; repeating the above steps until STM detection shows no impurity adsorption on the surface of the metal single crystal and contains more than 100 nm of impurities. 2 Up to the countertop.

[0015] In one or more embodiments of the present invention, the step of selecting a metal-organic material as an evaporation source and adsorbing it onto the surface of the metal single crystal includes: providing an MBE device, analyzing the metal-organic material source beam introduced into the MBE growth chamber using a beam detector equipped in the MBE chamber, and controlling the metal-organic material source beam current at 1×10⁻⁶. -6 Torr-1×10-5 Between Torr; place the metal single crystal into the MBE growth chamber, open the metal-organic source baffle to allow the metal-organic material to be adsorbed on the surface of the metal single crystal, and close the metal-organic source baffle 10~30s after the metal-organic material is deposited.

[0016] In one or more embodiments of the present invention, the substrate is heated at a heating rate of 10°C / min to 15°C / min, and the reaction time of the in-situ chemical reaction on the metal-organic surface is 10 to 30 s.

[0017] In one or more embodiments of the present invention, the preparation environment is an ultra-high vacuum environment, wherein the vacuum degree in the ultra-high vacuum environment is not less than 1*10. -7 Torr.

[0018] In one or more embodiments of the present invention, the purity of the organometallic compound is greater than or equal to 99.999%.

[0019] Compared with the prior art, the method for preparing single-atom-layer nitrides according to embodiments of the present invention, in an ultra-high vacuum chamber (vacuum degree not less than 1*10), -7 Torr uses organometallic compounds as metal and nitrogen sources. First, the metal single crystal is degassed and annealed in a vacuum chamber. Then, organometallic compounds are introduced into the chamber and physically adsorbed onto the surface of the metal single crystal. The metal single crystal is heated, and at a suitable temperature, the methyl groups of the organometallic compounds desorb. The organometallic compound system becomes unstable, and the original organometallic compound molecules undergo atomic rearrangement and molecular reassembly. Through in-situ chemical reactions, a single-atom-layer nitride is prepared.

[0020] According to the method for preparing monolayer nitrides according to embodiments of the present invention, organometallic compounds (trimethylaminogallium, trimethylaminoindium, trimethylaminoaluminum) that simultaneously possess metal and nitrogen sources are used as reaction precursors, and metal single crystals are used as substrates (Au, Ag, Cu, etc.). The desorption of methyl groups in the organometallic compounds is achieved by controlling the temperature during the growth process. The remaining Ga-N system is energy unstable, which will promote the reassembly of the molecules to form monolayer nitrides.

[0021] According to the method for preparing monolayer nitrides according to embodiments of the present invention, the growth rate of nitrides is controlled by controlling the beam flux of the metal-organic precursor, and the growth mode of nitrides is successfully transformed from layer-island bonding to two-dimensional layered mode, resulting in the growth of monolayer nitrides. This yields highly crystalline and highly flat self-supporting monolayer nitride materials, which is expected to pave the way for the fabrication of deep ultraviolet optoelectronic and power electronic devices. Attached Figure Description

[0022] Figure 1This is a process flow diagram of a method for preparing a single-atom-layer nitride according to an embodiment of the present invention;

[0023] Figure 2 This is a detailed process flow diagram of a method for preparing a single-atom-layer nitride according to an embodiment of the present invention;

[0024] Figure 3 It is the in-situ chemical reaction formula for the synthesis of GaN from trimethylaminogallium. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0026] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0027] As mentioned in the background section, single-atom-layer nitride semiconductors have significant application potential in optoelectronics, transparent electronic devices, and optoelectronic devices due to their special properties. However, single-atom-layer nitrides are sp3 orbital hybrids, which are prone to longitudinal bonding during growth and are difficult to obtain through traditional vapor phase growth or mechanical stripping methods.

[0028] To address the aforementioned technical challenges, this application creatively proposes a method for preparing single-atom-layer nitrides. This method involves growing single-atom-layer nitrides through in-situ chemical reactions on the surface of a metal-organic precursor. The nitrides that can be prepared include seven group III-V nitrides: GaN, AlN, InN, AlGaN, AlInN, InGaN, and AlGaInN. The grown single-atom-layer nitride crystals exhibit good crystallinity and high flatness, laying a solid foundation for the fabrication of highly integrated nitride devices.

[0029] like Figure 1 As shown, the method for preparing a single-atom-layer nitride according to an embodiment of the present invention specifically includes:

[0030] S1 provides a single metal crystal as a substrate.

[0031] S2 is used to clean, degas, and anneal metal single crystals.

[0032] s3 selects organometallic compounds as evaporation sources, causing them to adsorb onto the surface of the metal single crystal.

[0033] S4 heats the substrate to 350℃-450℃, causing the metal-organic materials on the substrate surface to decompose and undergo in-situ chemical reactions to generate monolayer nitrides.

[0034] In steps s1 and s2, the metal single crystal includes one of Au, Ag, and Cu.

[0035] refer to Figure 2 As shown, the cleaning process for metal single crystals includes the following steps:

[0036] S201 Removal of organic matter from the surface of metal single crystals: The metal single crystal is immersed in an organic solvent and subjected to ultrasonic treatment to remove organic matter from the surface of the metal single crystal. The organic solvents include ethanol and acetone.

[0037] S202 removal of oxides on the surface of metal single crystals: The metal single crystal is immersed in deionized water or pure water, and a reducing agent is added to remove the oxides on the surface of the metal single crystal. The reducing agent includes hydrofluoric acid (HF) and ferrous chloride (FeCl2).

[0038] S203 pickling: The metal single crystal is immersed in an acidic solution to remove residual oxides and impurities on the surface of the metal single crystal. The acidic solution includes concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4).

[0039] S204 alkaline washing: The metal single crystal is immersed in an alkaline solution to neutralize the acidic substances remaining on the surface of the metal single crystal and to clean the surface of the metal single crystal. The alkaline solution includes sodium hydroxide (NaOH) and ammonia (NH3·H2O).

[0040] S205 Rinsing: Immerse the metal single crystal in deionized water or pure water for multiple surface rinsings to ensure that no residual chemicals remain on the surface of the metal single crystal. S206 Drying: Dry the metal single crystal using nitrogen gas or under vacuum.

[0041] In step s2, the steps of degassing and annealing the metal single crystal specifically include:

[0042] The MBE (Metal Precipitation Electrode) equipment is provided to fix the metal single crystal onto the holder, and then transfer it into the sample injection chamber of the MBE. The sample injection chamber is kept in an ultra-high vacuum environment, with a vacuum level of not less than 1*10⁻⁶. -7 Torr;

[0043] The surface of the metal single crystal is bombarded with argon ions with an energy of 0.7-1.5 eV for 15-20 min. The metal single crystal is heated to 700℃-800℃ at a rate of 10-15℃ / min, then cooled to 380℃-400℃ at a rate of 10-15℃ / min, and held at that temperature for 18-22 min, preferably 20 min.

[0044] STM was used to detect the smoothness of a metal single crystal surface. This was considered when the metal single crystal surface had no impurities adsorbed and contained particles larger than 100nm. 2If the surface of the metal single crystal is clean, it proves that the metal single crystal is clean; otherwise, continue using argon ion and high-temperature annealing processes until STM detection shows that the surface of the metal single crystal has no impurities adsorbed and contains more than 100nm particles. 2 Up to the countertop.

[0045] Step s3, the step of selecting a metal-organic compound as an evaporation source and adsorbing it onto the surface of the metal single crystal, specifically includes:

[0046] The MEB (Metal-Organic Biotechnology) equipment is provided, and the beam detector equipped in the MBE chamber is used to analyze the metal-organic source beam introduced into the MBE growth chamber. By controlling the temperature at the top and bottom of the metal-organic crucible inside the MBE, the beam current of the metal-organic source is controlled at 1×10⁻⁶. -6 Torr-1×10 -5 Between Torr;

[0047] The metal single crystal is placed in the MBE growth chamber, and the growth chamber is kept in an ultra-high vacuum environment with a vacuum level of not less than 1*10. -7 Torr involves opening the metal-organic source baffle to allow the metal-organic compound to adsorb onto the surface of the metal single crystal, and then closing the baffle 10–30 seconds after deposition. The metal-organic compound is a metal-organic compound containing both a metal source and a nitrogen source, such as one or more of trimethylaminogallium, trimethylaminoindium, and trimethylaminoaluminum, with a purity greater than or equal to 99.999%.

[0048] In step s4, the substrate is heated to 350°C-450°C at a heating rate of 10°C / min to 15°C / min. At this temperature, the organometallic compounds on the substrate surface decompose, and the methyl groups in the organometallic compounds desorb, forming a monolayer nitride through an in-situ chemical reaction. Figure 3 As shown in the figure. The reaction time of the in-situ chemical reaction is 10~30s.

[0049] In this technical solution, the method for preparing monolayer nitrides according to the embodiments of the present invention uses organometallic compounds (trimethylaminogallium, trimethylaminoindium, trimethylaminoaluminum) that simultaneously possess metal and nitrogen sources as reaction precursors, and uses metal single crystals as substrates (Au, Ag, Cu, etc.). By controlling the temperature during the growth process, the methyl groups in the organometallic compounds are desorbed. The remaining Ga-N system is energy unstable, which will promote the reassembly of the molecules to form monolayer nitrides.

[0050] In this technical solution, the method for preparing monolayer nitrides according to the embodiments of the present invention controls the growth rate of nitrides by controlling the beam flux of the metal-organic precursor, and successfully transforms the nitride growth mode from layer-island bonding to two-dimensional layered mode, growing monolayer nitrides, thereby obtaining highly crystalline and highly flat self-supporting monolayer nitride materials, which is expected to pave the way for the fabrication of deep ultraviolet optoelectronic and power electronic devices.

[0051] Example 1

[0052] Au was used for the metal single crystal and trimethylaminogallium was used for the metal-organic composite.

[0053] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0054] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0055] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0056] To further remove impurities and expand the surface mesa of single-crystal Au, the single-crystal Au is subjected to the following operations: The single-crystal Au is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the single-crystal Au is then heated to 700-800℃ at a rate of 10-15℃ / min, and then cooled to 380-400℃ at a rate of 10-15℃ / min, followed by holding at that temperature for 18-22 min, preferably 20 min. The flatness of the single-crystal Au is then assessed using STM. A flat surface is considered desirable when there are no impurities adsorbed on the Au surface and no impurities exceeding 100 nm in size. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0057] The metal-organic source beam introduced into the MBE growth chamber—in this case, trimethylaminogallium—was analyzed using a beam detector equipped in the MBE chamber. By controlling the temperatures at the top and bottom of the metal-organic crucible within the MBE, the beam current of the trimethylaminogallium source was controlled at 1 × 10⁻⁶. -6 Torr-1×10 -5 Between Torr.

[0058] The treated single-crystal Au was placed in the MBE growth chamber. After opening the metal-organic evaporation source baffle, trimethylaminogallium adsorbed onto the surface of the single-crystal Au. After deposition for 10-30 seconds, the metal-organic evaporation source baffle was closed. The single-crystal Au was heated to 350-450℃ at a heating rate of 10℃ / min to 15℃ / min. At this temperature, the trimethylaminogallium on the surface of the single-crystal Au decomposed, and the methyl groups in the trimethylaminogallium desorbed, forming a single-atom-layer nitride through in-situ chemical reaction. The purity of the trimethylaminogallium reached 99.999%, and the reaction time of the in-situ chemical reaction was 10-30 seconds.

[0059] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0060] The sample was sealed in a vacuum bag and then removed for subsequent crystal quality characterization tests. Scanning electron microscopy, Auger electron spectroscopy, atomic force microscopy, and cathodoluminescence spectroscopy confirmed that the grown sample material was indeed a single-atom-layer nitride.

[0061] Example 2:

[0062] Au was used for the single metal crystals, and trimethylaminoin was used for the organometallic compounds.

[0063] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0064] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0065] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0066] To further remove impurities and expand the surface mesa of the single-crystal Au, the following operations are performed: The Au single-crystal is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the temperature is then increased to 700-800℃ at a rate of 10-15℃ / min, followed by decreasing to 380-400℃ at a rate of 10-15℃ / min and holding at that temperature for 18-22 min, preferably 20 min. The flatness of the Au single-crystal is then assessed using STM. A flatness is indicated when there are no impurities adsorbed on the Au surface and the surface area contains impurities larger than 100 nm. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0067] The metal-organic source beam introduced into the MBE growth chamber—in this case, trimethylaminoin—was analyzed using a beam detector equipped in the MBE chamber. By controlling the temperatures at the top and bottom of the metal-organic crucible within the MBE, the beam current of the trimethylaminoin source was controlled at 1 × 10⁻⁶. -6 Torr-1×10 -5 Between Torr.

[0068] The treated single-crystal Au was placed in the MBE growth chamber. After opening the baffle of the metal-organic evaporation source, trimethylaminoin was adsorbed on the surface of the single-crystal Au. After deposition for 10-30 seconds, the baffle of the metal-organic evaporation source was closed. The single-crystal Au was heated to 350-450℃ at a heating rate of 10℃ / min to 15℃ / min. At this temperature, the trimethylaminoin on the surface of the single-crystal Au decomposed, and the methyl groups in the trimethylaminoin were desorbed, forming a monolayer nitride through in-situ chemical reaction. The purity of the trimethylaminoin reached 99.999%, and the reaction time of the in-situ chemical reaction was 10-30 seconds.

[0069] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0070] The sample was sealed in a vacuum bag and then taken out for subsequent crystal quality characterization tests. Through scanning electron microscopy, atomic force microscopy, Auger electron spectroscopy, and cathodoluminescence spectroscopy, it can be determined that the grown sample material is indeed a single-atom-layer indium nitride.

[0071] Example 3:

[0072] Au was used for the metal single crystals, and trimethylaminoaluminum was used for the organometallic compounds.

[0073] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0074] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0075] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0076] To further remove impurities and expand the surface mesa of single-crystal Au, the single-crystal Au is subjected to the following operations: The single-crystal Au is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the single-crystal Au is then heated to 700-800℃ at a rate of 10-15℃ / min, and then cooled to 380-400℃ at a rate of 10-15℃ / min, and held at this temperature for 18-22 min, preferably 20 min. The flatness of the single-crystal Au is then assessed using STM. A flat surface is considered achieved when there are no impurities adsorbed on the Au surface and the surface area contains impurities larger than 100 nm. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0077] The metal-organic source beam introduced into the MBE growth chamber—in this case, trimethylaluminum amino acid—was analyzed using a beam detector equipped in the MBE chamber. The beam current of the trimethylaluminum amino acid source was controlled at 1 × 10⁻⁶ by adjusting the temperatures at the top and bottom of the metal-organic crucible within the MBE. -6 Torr-1×10 -5 Between Torr.

[0078] The treated single-crystal Au was placed in the MBE growth chamber. After opening the metal-organic evaporation source baffle, trimethylaluminum amino acid was adsorbed on the surface of the single-crystal Au. After deposition for 10-30 seconds, the metal-organic evaporation source baffle was closed. The single-crystal Au was heated to 350-450℃ at a heating rate of 10℃ / min to 15℃ / min. At this temperature, the trimethylaluminum amino acid on the surface of the single-crystal Au decomposed, and the methyl groups in the trimethylaluminum amino acid desorbed, forming a monolayer nitride through in-situ chemical reaction. The purity of the trimethylaluminum amino acid reached 99.999%, and the reaction time of the in-situ chemical reaction was 10-30 seconds.

[0079] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0080] The sample was sealed in a vacuum bag and then taken out for subsequent crystal quality characterization tests. Through scanning electron microscopy, atomic force microscopy, Auger electron spectroscopy, and cathodoluminescence spectroscopy, it can be determined that the grown sample material is indeed a single-atom-layer aluminum nitride.

[0081] Example 4

[0082] The metal single crystal uses Au, and the metal-organic materials use trimethylaminogallium and trimethylaminoaluminum.

[0083] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0084] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0085] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0086] To further remove impurities and expand the surface mesa of single-crystal Au, the single-crystal Au is subjected to the following operations: The single-crystal Au is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the single-crystal Au is then heated to 700-800℃ at a rate of 10-15℃ / min, and then cooled to 380-400℃ at a rate of 10-15℃ / min, followed by holding at that temperature for 18-22 min, preferably 20 min. The flatness of the single-crystal Au is then assessed using STM. A flat surface is considered desirable when there are no impurities adsorbed on the Au surface and no impurities exceeding 100 nm in size. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0087] The metal-organic source beams introduced into the MBE growth chamber—here, trimethylaminogallium (TMG) and trimethylaminoaluminum (TMA)—were analyzed using a beam detector equipped in the MBE chamber. By controlling the temperatures at the top and bottom of the MBE metal-organic crucible, the beams of the TMG and TMA sources were controlled at 1 × 10⁻⁶. -6 Torr-1×10 -5 Between Torr.

[0088] The treated single-crystal Au is placed in the MBE growth chamber. With both organic evaporation source baffles opened, trimethylaminogallium and trimethylaminoaluminum adsorbed onto the Au surface. After deposition for 10–30 seconds, the metal-organic evaporation source baffles are closed. The Au single-crystal is then heated to 350–450°C at a rate of 10–15°C / min. At this temperature, the trimethylaminogallium and trimethylaminoaluminum on the Au surface decompose, and the methyl groups in the trimethylaminogallium and trimethylaminoaluminum desorb, forming a single-atom-layer nitride through an in-situ chemical reaction. The purity of the trimethylaminogallium and trimethylaminoaluminum reaches 99.999%, and the reaction time of the in-situ chemical reaction is 10–30 seconds.

[0089] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0090] The sample was sealed in a vacuum bag and then removed for subsequent crystal quality characterization tests. Scanning electron microscopy, Auger electron spectroscopy, atomic force microscopy, and cathodoluminescence spectroscopy confirmed that the grown sample material was indeed a single-atom-layer ternary nitride, aluminum gallium nitride.

[0091] Example 5

[0092] The metal single crystal is made of Au, and the metal-organic compound is made of trimethylaminoaluminum and trimethylaminoin.

[0093] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0094] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0095] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0096] To further remove impurities and expand the surface mesa of single-crystal Au, the single-crystal Au is subjected to the following operations: The single-crystal Au is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the single-crystal Au is then heated to 700-800℃ at a rate of 10-15℃ / min, and then cooled to 380-400℃ at a rate of 10-15℃ / min, followed by holding at that temperature for 18-22 min, preferably 20 min. The flatness of the single-crystal Au is then assessed using STM. A flat surface is considered desirable when there are no impurities adsorbed on the Au surface and no impurities exceeding 100 nm in size. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0097] The metal-organic source beams introduced into the MBE growth chamber—in this case, trimethylaminoaluminum and trimethylaminoin—were analyzed using a beam detector equipped in the MBE chamber. By controlling the temperatures at the top and bottom of the metal-organic crucible within the MBE, the beam currents of the trimethylaminoaluminum and trimethylaminoin sources were controlled at 1 × 10⁻⁶. -6 Torr-1×10 -5 Between Torr.

[0098] The treated single-crystal Au is placed in the MBE growth chamber. With both organic evaporation source baffles opened, trimethylaminoaluminum and trimethylaminoin are adsorbed onto the Au surface. After deposition for 10–30 seconds, the metal-organic evaporation source baffles are closed. The Au single-crystal is then heated to 350–450°C at a rate of 10–15°C / min. At this temperature, the trimethylaminoaluminum and trimethylaminoin on the Au surface decompose, and the methyl groups in the trimethylaminoaluminum and trimethylaminoin desorb, forming a single-atom-layer nitride through an in-situ chemical reaction. The purity of the trimethylaminoaluminum and trimethylaminoin reaches 99.999%, and the reaction time of the in-situ chemical reaction is 10–30 seconds.

[0099] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0100] The sample was sealed in a vacuum bag and then removed for subsequent crystal quality characterization tests. Scanning electron microscopy, Auger electron spectroscopy, atomic force microscopy, and cathodoluminescence spectroscopy confirmed that the grown sample material was indeed a single-atom-layer ternary nitride, aluminum indium nitrogen.

[0101] Example 6

[0102] Au is used for the single metal crystals, and trimethylaminogallium and trimethylaminoin are used for the organometallic compounds.

[0103] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0104] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0105] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0106] To further remove impurities and expand the surface mesa of single-crystal Au, the single-crystal Au is subjected to the following operations: The single-crystal Au is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the single-crystal Au is then heated to 700-800℃ at a rate of 10-15℃ / min, and then cooled to 380-400℃ at a rate of 10-15℃ / min, followed by holding at that temperature for 18-22 min, preferably 20 min. The flatness of the single-crystal Au is then assessed using STM. A flat surface is considered desirable when there are no impurities adsorbed on the Au surface and no impurities exceeding 100 nm in size. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0107] The metal-organic source beams introduced into the MBE growth chamber—here, trimethylaminogallium (TMG) and trimethylaminoin (TIA)—were analyzed using a beam detector equipped in the MBE chamber. By controlling the temperatures at the top and bottom of the MBE metal-organic crucible, the beams of the TMG and TIA sources were controlled at 1 × 10⁻⁶. -6 Torr-1×10 -5 Between Torr.

[0108] The treated single-crystal Au is placed in the MBE growth chamber. With both organic evaporation source baffles opened, trimethylaminogallium (TMGa) and trimethylaminoin (TMI) are adsorbed onto the Au surface. After deposition for 10–30 seconds, the MME baffles are closed. The Au is then heated to 350–450°C at a rate of 10–15°C / min. At this temperature, the TME and TMI on the Au surface decompose, and the methyl groups in TME and TMI desorb, forming a single-atom-layer nitride through an in-situ chemical reaction. The purity of TME and TMI reaches 99.999%, and the reaction time of the in-situ chemical reaction is 10–30 seconds.

[0109] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0110] The sample was sealed in a vacuum bag and then removed for subsequent crystal quality characterization tests. Scanning electron microscopy, Auger electron spectroscopy, atomic force microscopy, and cathodoluminescence spectroscopy confirmed that the grown sample material was indeed a single-atom-layer ternary nitride, indium gallium nitride.

[0111] Example 7

[0112] The metal single crystal uses Au, and the metal-organic materials use trimethylaminoaluminum, trimethylaminogallium, and trimethylaminoin.

[0113] Clean the beaker. Clean the beaker with deionized water using ultrasonic cleaning, then with acetone using ultrasonic cleaning, repeating several times.

[0114] Cleaning of Au single crystal: 1. Remove surface organic matter: Immerse the Au single crystal in an organic solvent, such as ethanol or acetone, and use ultrasonic treatment to remove more organic matter. 2. Remove surface oxides: Immerse the Au single crystal in deionized water or pure water, adding reducing agents such as hydrofluoric acid (HF) or ferrous chloride (FeCl2) to remove surface oxides. 3. Acid washing: Immerse the Au single crystal in an acidic solution, such as concentrated nitric acid (HNO3) or concentrated sulfuric acid (H2SO4), to remove residual oxides and other impurities on the surface. 4. Alkaline washing: Immerse the Au single crystal in an alkaline solution, such as sodium hydroxide (NaOH) or ammonia (NH3·H2O), to neutralize residual acidic substances in the acidic solution and clean the surface. 5. Rinse again with deionized water: Immerse the Au single crystal in deionized water or pure water and rinse repeatedly to ensure that no chemical residue remains on the surface. 6. Dry with nitrogen or under vacuum.

[0115] The single-crystal Au was fixed onto the support and then transferred into the MBE injection chamber. The back-bottom vacuum of the MBE injection chamber was maintained at 1*10. -7 torr.

[0116] To further remove impurities and expand the surface mesa of single-crystal Au, the single-crystal Au is subjected to the following operations: The single-crystal Au is bombarded with argon ions at an energy of 0.7-1.5 eV for 15-20 min; the single-crystal Au is then heated to 700-800℃ at a rate of 10-15℃ / min, and then cooled to 380-400℃ at a rate of 10-15℃ / min, followed by holding at that temperature for 18-22 min, preferably 20 min. The flatness of the single-crystal Au is then assessed using STM. A flat surface is considered desirable when there are no impurities adsorbed on the Au surface and no impurities exceeding 100 nm in size. 2 If the countertop is clean, it proves that it is clean. If it does not meet the standard, continue with the argon ion and high-temperature annealing process.

[0117] The metal-organic source beams introduced into the MBE growth chamber—here, trimethylaminogallium, trimethylaminoaluminum, and trimethylaminoin—were analyzed using a beam detector equipped in the MBE chamber. By controlling the temperature at the top and bottom of the metal-organic crucible within the MBE, the beams of the trimethylaminogallium, trimethylaminoaluminum, and trimethylaminoin sources were controlled at 1 × 10⁻⁶. -6 Torr-1×10 -5Between Torr. The treated single-crystal Au is placed in the MBE growth chamber. With the three organic evaporation source baffles simultaneously opened, trimethylaminogallium, trimethylaminoin, and trimethylaminoaluminum adsorbs onto the Au surface. After deposition for 10-30 seconds, the metal-organic evaporation source baffles are closed. The Au single-crystal is then heated to 350-450°C at a rate of 10-15°C / min. At this temperature, the trimethylaminogallium, trimethylaminoaluminum, and trimethylaminoin on the Au surface decompose, and the methyl groups in these compounds desorb, forming a single-atom-layer nitride through in-situ chemical reaction. The purity of trimethylaminoaluminum, trimethylaminogallium, and trimethylaminoin reaches 99.999%, and the reaction time of the in-situ chemical reaction is 10-30 seconds.

[0118] Once the reaction is complete, the tube will be transferred out of the growth chamber.

[0119] The sample was sealed in a vacuum bag and then removed for subsequent crystal quality characterization tests. Scanning electron microscopy, Auger electron spectroscopy, atomic force microscopy, and cathodoluminescence spectroscopy confirmed that the grown sample material was indeed a single-atom-layer ternary nitride, aluminum gallium indium nitride.

[0120] Comparative example:

[0121] The parameters such as the beam current of the metal-organic source, the metal-organic deposition time, the substrate heating rate, the substrate heating height, and the in-situ chemical reaction time were changed, while other experimental conditions were the same as in Example 1. The results are compared in Table 1 below.

[0122] Table 1

[0123]

[0124] Comparative Examples 1 and 2 show that the beam current and deposition time of the metal-organic source have the following effects on the preparation of monolayer nitrides: The beam current and deposition time together determine the amount of metal-organic material deposited on the substrate. In the same amount of time, if the beam current is too high, the amount of metal-organic material will be excessive, leading to metal-organic agglomeration and the formation of nitride islands. Conversely, if the beam current is too low, the amount of metal-organic material will be too small, resulting in nitrides that are too small to form a film.

[0125] Comparative Examples 3 and 4 show that the substrate heating rate has the following effect on the preparation of monolayer nitrides: the faster the heating rate, the less uniform the desorption of methyl groups in the organometallic molecules will be, and the self-assembly process will begin before the methyl groups are completely desorbed, resulting in an impure sample; if the heating rate is too slow, some methyl groups will be re-adsorbed onto the sample surface after desorption, resulting in an impure sample.

[0126] Comparative Examples 5 and 6 show that the substrate temperature has the following effects on the preparation of monolayer nitrides: If the substrate temperature is too low, the reaction cannot occur, and the methyl groups cannot be desorbed. If the substrate temperature is too high, the reaction will occur too quickly, and the assembled structure will become disordered.

[0127] Comparative Examples 7 and 8 show that the duration of the in-situ chemical reaction has the following effect on the preparation of monolayer nitrides: Too short a reaction time may lead to incomplete and unstable nitride layers. Too long a time may result in over-crystallization, leading to defects and impurities.

[0128] In summary, according to the method for preparing monolayer nitrides according to embodiments of the present invention, organometallic compounds (trimethylaminogallium, trimethylaminoindium, trimethylaminoaluminum) that simultaneously possess both a metal source and a nitrogen source are used as reaction precursors, and metal single crystals are used as substrates (Au, Ag, Cu, etc.). By controlling the temperature during the growth process, methyl groups in the organometallic compounds are desorbed. The remaining Ga-N system is energy unstable, which promotes internal molecular reassembly to form monolayer nitrides.

[0129] According to the method for preparing monolayer nitrides according to embodiments of the present invention, the growth rate of nitrides is controlled by controlling the beam flux of the metal-organic precursor, and the growth mode of nitrides is successfully transformed from layer-island bonding to two-dimensional layered mode, resulting in the growth of monolayer nitrides. This yields highly crystalline and highly flat self-supporting monolayer nitride materials, which is expected to pave the way for the fabrication of deep ultraviolet optoelectronic and power electronic devices.

[0130] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing a single-atom-layer nitride, characterized in that, include: Provide a single metal crystal as the substrate; Organometallic compounds are selected as evaporation sources and adsorbed onto the surface of the metal single crystal. The organometallic compounds include one or more of trimethylaminogallium, trimethylaminoindium, and trimethylaminoaluminum. The substrate is heated to 350℃-450℃ at a heating rate of 10℃ / min to 15℃ / min, and the metal-organic matter on the surface of the substrate decomposes and undergoes a surface in-situ chemical reaction. The reaction time of the surface in-situ chemical reaction is 10-30s, generating a single-atom-layer nitride. The step of selecting a metal-organic compound as an evaporation source and adsorbing it onto the surface of the metal single crystal includes: Provide MBE equipment, and use the beam detector equipped in the MBE chamber to analyze the metal-organic source beam introduced into the MBE growth chamber, controlling the metal-organic source beam current at 1×10 -6 Torr-1×10 -5 Between Torr; The metal single crystal is placed in the MBE growth chamber, the metal-organic source baffle is opened to allow the metal-organic material to be adsorbed on the surface of the metal single crystal, and the metal-organic source baffle is closed after the metal-organic material has been deposited for 10 to 30 seconds.

2. The method for preparing a single-atom-layer nitride as described in claim 1, characterized in that, The metal single crystal includes one of Au, Ag, and Cu.

3. The method for preparing a single-atom-layer nitride as described in claim 1, characterized in that, Before the step of adsorbing the metal-organic compound onto the surface of the metal single crystal, the method further includes the steps of cleaning, degassing, and annealing the metal single crystal.

4. The method for preparing a single-atom-layer nitride as described in claim 3, characterized in that, The steps for cleaning metal single crystals include: The metal single crystal was immersed in an organic solvent and then subjected to ultrasonic treatment to remove organic matter from the surface of the metal single crystal. The metal single crystal is immersed in deionized water or pure water, and a reducing agent is added to remove the oxides on the surface of the metal single crystal. The metal single crystal is immersed in an acidic solution to remove residual oxides and impurities from the surface of the metal single crystal; The metal single crystal is immersed in an alkaline solution to neutralize the acidic substances on the surface of the metal single crystal and to clean the surface of the metal single crystal. The metal single crystal is immersed in deionized water or pure water for surface rinsing, and then dried with nitrogen or under vacuum.

5. The method for preparing a single-atom-layer nitride as described in claim 4, characterized in that, The organic solvent includes ethanol, acetone; and / or The reducing agent includes hydrofluoric acid, ferrous chloride; and / or The acidic solution includes nitric acid, sulfuric acid; and / or The alkaline solution includes sodium hydroxide and ammonia.

6. The method for preparing a single-atom-layer nitride as described in claim 3, characterized in that, The steps for degassing and annealing metal single crystals include: The surface of the metal single crystal is bombarded with argon ions with an energy of 0.7-1.5 eV for 15-20 min. The metal single crystal is heated to 700℃-800℃ at a rate of 10-15℃ / min, then cooled to 380℃-400℃ at a rate of 10-15℃ / min, and held at that temperature for 18-22 min. Repeat the above steps until the surface of the metal single crystal is free of impurity adsorption and contains more than 100 nm particles as detected by STM. 2 Up to the countertop.

7. The method for preparing a single-atom-layer nitride as described in claim 1, characterized in that, The preparation environment is an ultra-high vacuum environment, and the vacuum level in the ultra-high vacuum environment is not less than 1*10. -7 Torr; and / or, The purity of the organometallic compound is greater than or equal to 99.999%.

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