An epitaxial lift-off process for graphene-based gallium nitride (GaN), comprising the following steps: (1) growing graphene on a well-polished copper foil: (la) folding a well-polished copper foil into a moderate-sized purse, putting the purse in a quartz boat, pushing the boat to a constant temperature zone in the middle of a quartz tube, and turning on a vacuum pump to vacuumize to 0.6-2 Pa; (l b) introducing 20-25 s cc m H 2 into the quartz tube, while heating the quartz tube; introducing both 20-25 s cc m H 2 and 700-720 s cc m Ar into the quartz tube when reaching a temperature of 700 ° C, and continuing heating until the quartz tube reaches a temperature of 1,045-1,050 °C; (1c) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to 0.6-2 Pa with the vacuum pump; (1 d) holding the temperature, introducing 2 s ccm 02 into the quartz tube, and maintaining for 2 min; (le) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to around 1 Pa with the vacuum pump; (i f) holding the temperature, introducing both 100 s cc m H 2 and 700 s cc m Ar, and maintaining for 60 m in; (1 g) holding the temperature, closing an Ar gas valve, introducing both 0.1-1 s cc m CH₄ and 400-600 s cc m H 2, and maintaining for 60 m in; and (1 h) maintaining the fl ow rates of H 2 and CH4, rapidly cooling down the quartz tube to room temperature, and removing the graphene grown on the copper foil, which is 0.34 nm thick; (2) transferring the graphene grown on the copper foil onto a sapphire substrate: (2a) manually coating a layer of polymethyl methacrylate (PMMA) fi lm on the surface of the graphene-grown copper foil, and spin-coating PMMA uniformly with a spin coater, to obtain a copper foil spin-coated with PMMA; (2b) placing the copper foil spin-coated with PMMA on a heating stage, setting a temperature thereof at 50-70 ° C, and drying for 20 m in to cure the PMMA fi lm; (2c) cutting the PMMA-cured copper foil into a plurality of small sheets of equivalent size and soaking in 64-68 g/L ammonium persulfate solution; with a graphene side facing upward, dipping for 4-12 h, and removing a metal substrate, to obtain a plurality of monolayer graphene fi lms with PMMA; (2d) using a clean glass sheet to transfer a plurality of PMMA/graphene sheets from the ammonium persulfate solution into deionized water; after soaking for 30 m in, using a sapphire substrate to pull out one of the small PMMA/monolayer graphene sheets therefrom, to obtain a sapphire substrate coated with PMMA/monolayer graphene; (2e) adding 100-200 ml of acetone solution into a glass container, and immersing the PMMA/monolayer graphene/substrate thoroughly for 12-24 h to dissolve and remove PMMA fully, to obtain a PMMA-free monolayer graphene/substrate; (2f) transferring the PMMA-free monolayer graphene/substrate from the acetone solution into an ethanol solution to be allowed to stand for 30 m in, pulling out the monolayer graphene/substrate subsequently, and air-drying to complete the transfer of the monolayer graphene; and (2g) using a monolayer graphene-transferred sapphire substrate to pull out a second PMMA/monolayer graphene fi lm, to obtain a substrate coated with PMMA/bilayer graphene; repeating steps (2e) to (2f) to complete the transfer of the second layer of graphene; similarly, pulling out the third to the fi nal PMMA/graphene fi lms to complete the transfer of the third to the fi nal layers of graphene fi lms; (3) growing GaN epitaxial layer by the metal organic chemical vapor deposition (MOCVD) method (3a) placing the graphene-transferred substrate in a reaction chamber and introducing ammonia thereinto; heating the reaction chamber to 900 0 C, and adjusting the pressure of the reaction chamber to 300 mbar; (3b) maintaining the reaction chamber at a constant pressure, heating the reaction chamber to a temperature of 1,1 00 0 C, and simultaneously introducing H 2, ammonia, and Ga source thereinto, wherein fl ow rates of the three gases are 800-1,000 s c cm, 9,600-10,500 s c cm, and 230-260 s c cm, respectively; using the MOCVD method, growing 1-3 um GaN on the graphene-transferred substrate; and (3d) removing a sample after cooling down the reaction chamber to room temperature, to obtain GaN grown on the graphene; (4) lifting off the GaN epitaxial layer: (4a) slowly adhering a thermal release tape to an upper surface of the GaN epitaxial layer, applying a uniform force to lift the tape having the GaN epitaxial layer adhered thereto off the original substrate completely; (4b) adhering the GaN-adhered side of the thermal release tape to a target substrate tightly, heating the heating stage to 120 0 C, subsequently placing the target substrate on the heating stage wholly, and heating for 5 m in, wherein, the thermal release tape loses viscosity after foaming and will spontaneously lift off the surface of GaN; and (4c) removing the lift-off tape using tweezers, and leaving the GaN epitaxial layer on the target substrate to realize the lift-off and transfer of the GaN epitaxial layer.

An epitaxial lift-off process for graphene-based gallium nitride (GaN), comprising the following steps: (1) growing graphene on a well-polished copper foil: (la) folding a well-polished copper foil into a moderate-sized purse, putting the purse in a quartz boat, pushing the boat to a constant temperature zone in the middle of a quartz tube, and turning on a vacuum pump to vacuumize to 0.6-2 Pa; (l b) introducing 20-25 s cc m H 2 into the quartz tube, while heating the quartz tube; introducing both 20-25 s cc m H 2 and 700-720 s cc m Ar into the quartz tube when reaching a temperature of 700 ° C, and continuing heating until the quartz tube reaches a temperature of 1,045-1,050 °C; (1c) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to 0.6-2 Pa with the vacuum pump; (1 d) holding the temperature, introducing 2 s ccm 02 into the quartz tube, and maintaining for 2 min; (le) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to around 1 Pa with the vacuum pump; (i f) holding the temperature, introducing both 100 s cc m H 2 and 700 s cc m Ar, and maintaining for 60 m in; (1 g) holding the temperature, closing an Ar gas valve, introducing both 0.1-1 s cc m CH₄ and 400-600 s cc m H 2, and maintaining for 60 m in; and (1 h) maintaining the fl ow rates of H 2 and CH4, rapidly cooling down the quartz tube to room temperature, and removing the graphene grown on the copper foil, which is 0.34 nm thick; (2) transferring the graphene grown on the copper foil onto a sapphire substrate: (2a) manually coating a layer of polymethyl methacrylate (PMMA) fi lm on the surface of the graphene-grown copper foil, and spin-coating PMMA uniformly with a spin coater, to obtain a copper foil spin-coated with PMMA; (2b) placing the copper foil spin-coated with PMMA on a heating stage, setting a temperature thereof at 50-70 ° C, and drying for 20 m in to cure the PMMA fi lm; (2c) cutting the PMMA-cured copper foil into a plurality of small sheets of equivalent size and soaking in 64-68 g/L ammonium persulfate solution; with a graphene side facing upward, dipping for 4-12 h, and removing a metal substrate, to obtain a plurality of monolayer graphene fi lms with PMMA; (2d) using a clean glass sheet to transfer a plurality of PMMA/graphene sheets from the ammonium persulfate solution into deionized water; after soaking for 30 m in, using a sapphire substrate to pull out one of the small PMMA/monolayer graphene sheets therefrom, to obtain a sapphire substrate coated with PMMA/monolayer graphene; (2e) adding 100-200 ml of acetone solution into a glass container, and immersing the PMMA/monolayer graphene/substrate thoroughly for 12-24 h to dissolve and remove PMMA fully, to obtain a PMMA-free monolayer graphene/substrate; (2f) transferring the PMMA-free monolayer graphene/substrate from the acetone solution into an ethanol solution to be allowed to stand for 30 m in, pulling out the monolayer graphene/substrate subsequently, and air-drying to complete the transfer of the monolayer graphene; and (2g) using a monolayer graphene-transferred sapphire substrate to pull out a second PMMA/monolayer graphene fi lm, to obtain a substrate coated with PMMA/bilayer graphene; repeating steps (2e) to (2f) to complete the transfer of the second layer of graphene; similarly, pulling out the third to the fi nal PMMA/graphene fi lms to complete the transfer of the third to the fi nal layers of graphene fi lms; (3) growing GaN epitaxial layer by the metal organic chemical vapor deposition (MOCVD) method (3a) placing the graphene-transferred substrate in a reaction chamber and introducing ammonia thereinto; heating the reaction chamber to 900 0 C, and adjusting the pressure of the reaction chamber to 300 mbar; (3b) maintaining the reaction chamber at a constant pressure, heating the reaction chamber to a temperature of 1,1 00 0 C, and simultaneously introducing H 2, ammonia, and Ga source thereinto, wherein fl ow rates of the three gases are 800-1,000 s c cm, 9,600-10,500 s c cm, and 230-260 s c cm, respectively; using the MOCVD method, growing 1-3 um GaN on the graphene-transferred substrate; and (3d) removing a sample after cooling down the reaction chamber to room temperature, to obtain GaN grown on the graphene; (4) lifting off the GaN epitaxial layer: (4a) slowly adhering a thermal release tape to an upper surface of the GaN epitaxial layer, applying a uniform force to lift the tape having the GaN epitaxial layer adhered thereto off the original substrate completely; (4b) adhering the GaN-adhered side of the thermal release tape to a target substrate tightly, heating the heating stage to 120 0 C, subsequently placing the target substrate on the heating stage wholly, and heating for 5 m in, wherein, the thermal release tape loses viscosity after foaming and will spontaneously lift off the surface of GaN; and (4c) removing the lift-off tape using tweezers, and leaving the GaN epitaxial layer on the target substrate to realize the lift-off and transfer of the GaN epitaxial layer.

An epitaxial lift-off process for graphene-based gallium nitride (GaN), comprising the following steps: (1) growing graphene on a well-polished copper foil: (la) folding a well-polished copper foil into a moderate-sized purse, putting the purse in a quartz boat, pushing the boat to a constant temperature zone in the middle of a quartz tube, and turning on a vacuum pump to vacuumize to 0.6-2 Pa; (l b) introducing 20-25 s cc m H 2 into the quartz tube, while heating the quartz tube; introducing both 20-25 s cc m H 2 and 700-720 s cc m Ar into the quartz tube when reaching a temperature of 700 ° C, and continuing heating until the quartz tube reaches a temperature of 1,045-1,050 °C; (1c) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to 0.6-2 Pa with the vacuum pump; (1 d) holding the temperature, introducing 2 s ccm 02 into the quartz tube, and maintaining for 2 min; (le) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to around 1 Pa with the vacuum pump; (i f) holding the temperature, introducing both 100 s cc m H 2 and 700 s cc m Ar, and maintaining for 60 m in; (1 g) holding the temperature, closing an Ar gas valve, introducing both 0.1-1 s cc m CH₄ and 400-600 s cc m H 2, and maintaining for 60 m in; and (1 h) maintaining the fl ow rates of H 2 and CH4, rapidly cooling down the quartz tube to room temperature, and removing the graphene grown on the copper foil, which is 0.34 nm thick; (2) transferring the graphene grown on the copper foil onto a sapphire substrate: (2a) manually coating a layer of polymethyl methacrylate (PMMA) fi lm on the surface of the graphene-grown copper foil, and spin-coating PMMA uniformly with a spin coater, to obtain a copper foil spin-coated with PMMA; (2b) placing the copper foil spin-coated with PMMA on a heating stage, setting a temperature thereof at 50-70 ° C, and drying for 20 m in to cure the PMMA fi lm; (2c) cutting the PMMA-cured copper foil into a plurality of small sheets of equivalent size and soaking in 64-68 g/L ammonium persulfate solution; with a graphene side facing upward, dipping for 4-12 h, and removing a metal substrate, to obtain a plurality of monolayer graphene fi lms with PMMA; (2d) using a clean glass sheet to transfer a plurality of PMMA/graphene sheets from the ammonium persulfate solution into deionized water; after soaking for 30 m in, using a sapphire substrate to pull out one of the small PMMA/monolayer graphene sheets therefrom, to obtain a sapphire substrate coated with PMMA/monolayer graphene; (2e) adding 100-200 ml of acetone solution into a glass container, and immersing the PMMA/monolayer graphene/substrate thoroughly for 12-24 h to dissolve and remove PMMA fully, to obtain a PMMA-free monolayer graphene/substrate; (2f) transferring the PMMA-free monolayer graphene/substrate from the acetone solution into an ethanol solution to be allowed to stand for 30 m in, pulling out the monolayer graphene/substrate subsequently, and air-drying to complete the transfer of the monolayer graphene; and (2g) using a monolayer graphene-transferred sapphire substrate to pull out a second PMMA/monolayer graphene fi lm, to obtain a substrate coated with PMMA/bilayer graphene; repeating steps (2e) to (2f) to complete the transfer of the second layer of graphene; similarly, pulling out the third to the fi nal PMMA/graphene fi lms to complete the transfer of the third to the fi nal layers of graphene fi lms; (3) growing GaN epitaxial layer by the metal organic chemical vapor deposition (MOCVD) method (3a) placing the graphene-transferred substrate in a reaction chamber and introducing ammonia thereinto; heating the reaction chamber to 900 0 C, and adjusting the pressure of the reaction chamber to 300 mbar; (3b) maintaining the reaction chamber at a constant pressure, heating the reaction chamber to a temperature of 1,1 00 0 C, and simultaneously introducing H 2, ammonia, and Ga source thereinto, wherein fl ow rates of the three gases are 800-1,000 s c cm, 9,600-10,500 s c cm, and 230-260 s c cm, respectively; using the MOCVD method, growing 1-3 um GaN on the graphene-transferred substrate; and (3d) removing a sample after cooling down the reaction chamber to room temperature, to obtain GaN grown on the graphene; (4) lifting off the GaN epitaxial layer: (4a) slowly adhering a thermal release tape to an upper surface of the GaN epitaxial layer, applying a uniform force to lift the tape having the GaN epitaxial layer adhered thereto off the original substrate completely; (4b) adhering the GaN-adhered side of the thermal release tape to a target substrate tightly, heating the heating stage to 120 0 C, subsequently placing the target substrate on the heating stage wholly, and heating for 5 m in, wherein, the thermal release tape loses viscosity after foaming and will spontaneously lift off the surface of GaN; and (4c) removing the lift-off tape using tweezers, and leaving the GaN epitaxial layer on the target substrate to realize the lift-off and transfer of the GaN epitaxial layer.

An epitaxial lift-off process for graphene-based gallium nitride (GaN), comprising the following steps: (1) growing graphene on a well-polished copper foil: (la) folding a well-polished copper foil into a moderate-sized purse, putting the purse in a quartz boat, pushing the boat to a constant temperature zone in the middle of a quartz tube, and turning on a vacuum pump to vacuumize to 0.6-2 Pa; (l b) introducing 20-25 s cc m H 2 into the quartz tube, while heating the quartz tube; introducing both 20-25 s cc m H 2 and 700-720 s cc m Ar into the quartz tube when reaching a temperature of 700 ° C, and continuing heating until the quartz tube reaches a temperature of 1,045-1,050 °C; (1c) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to 0.6-2 Pa with the vacuum pump; (1 d) holding the temperature, introducing 2 s ccm 02 into the quartz tube, and maintaining for 2 min; (le) holding the temperature, closing all inlet valves, and vacuumizing the quartz tube to around 1 Pa with the vacuum pump; (i f) holding the temperature, introducing both 100 s cc m H 2 and 700 s cc m Ar, and maintaining for 60 m in; (1 g) holding the temperature, closing an Ar gas valve, introducing both 0.1-1 s cc m CH₄ and 400-600 s cc m H 2, and maintaining for 60 m in; and (1 h) maintaining the fl ow rates of H 2 and CH4, rapidly cooling down the quartz tube to room temperature, and removing the graphene grown on the copper foil, which is 0.34 nm thick; (2) transferring the graphene grown on the copper foil onto a sapphire substrate: (2a) manually coating a layer of polymethyl methacrylate (PMMA) fi lm on the surface of the graphene-grown copper foil, and spin-coating PMMA uniformly with a spin coater, to obtain a copper foil spin-coated with PMMA; (2b) placing the copper foil spin-coated with PMMA on a heating stage, setting a temperature thereof at 50-70 ° C, and drying for 20 m in to cure the PMMA fi lm; (2c) cutting the PMMA-cured copper foil into a plurality of small sheets of equivalent size and soaking in 64-68 g/L ammonium persulfate solution; with a graphene side facing upward, dipping for 4-12 h, and removing a metal substrate, to obtain a plurality of monolayer graphene fi lms with PMMA; (2d) using a clean glass sheet to transfer a plurality of PMMA/graphene sheets from the ammonium persulfate solution into deionized water; after soaking for 30 m in, using a sapphire substrate to pull out one of the small PMMA/monolayer graphene sheets therefrom, to obtain a sapphire substrate coated with PMMA/monolayer graphene; (2e) adding 100-200 ml of acetone solution into a glass container, and immersing the PMMA/monolayer graphene/substrate thoroughly for 12-24 h to dissolve and remove PMMA fully, to obtain a PMMA-free monolayer graphene/substrate; (2f) transferring the PMMA-free monolayer graphene/substrate from the acetone solution into an ethanol solution to be allowed to stand for 30 m in, pulling out the monolayer graphene/substrate subsequently, and air-drying to complete the transfer of the monolayer graphene; and (2g) using a monolayer graphene-transferred sapphire substrate to pull out a second PMMA/monolayer graphene fi lm, to obtain a substrate coated with PMMA/bilayer graphene; repeating steps (2e) to (2f) to complete the transfer of the second layer of graphene; similarly, pulling out the third to the fi nal PMMA/graphene fi lms to complete the transfer of the third to the fi nal layers of graphene fi lms; (3) growing GaN epitaxial layer by the metal organic chemical vapor deposition (MOCVD) method (3a) placing the graphene-transferred substrate in a reaction chamber and introducing ammonia thereinto; heating the reaction chamber to 900 0 C, and adjusting the pressure of the reaction chamber to 300 mbar; (3b) maintaining the reaction chamber at a constant pressure, heating the reaction chamber to a temperature of 1,1 00 0 C, and simultaneously introducing H 2, ammonia, and Ga source thereinto, wherein fl ow rates of the three gases are 800-1,000 s c cm, 9,600-10,500 s c cm, and 230-260 s c cm, respectively; using the MOCVD method, growing 1-3 um GaN on the graphene-transferred substrate; and (3d) removing a sample after cooling down the reaction chamber to room temperature, to obtain GaN grown on the graphene; (4) lifting off the GaN epitaxial layer: (4a) slowly adhering a thermal release tape to an upper surface of the GaN epitaxial layer, applying a uniform force to lift the tape having the GaN epitaxial layer adhered thereto off the original substrate completely; (4b) adhering the GaN-adhered side of the thermal release tape to a target substrate tightly, heating the heating stage to 120 0 C, subsequently placing the target substrate on the heating stage wholly, and heating for 5 m in, wherein, the thermal release tape loses viscosity after foaming and will spontaneously lift off the surface of GaN; and (4c) removing the lift-off tape using tweezers, and leaving the GaN epitaxial layer on the target substrate to realize the lift-off and transfer of the GaN epitaxial layer.