Patent ID: 8383494

Claim:
A method for forming a buffer layer for growing gallium nitride single crystals on a sapphire substrate using hydride vapor phase epitaxy (HVPE), wherein the buffer layer is formed in the form of an undoped vertical gallium nitride (GaN) single crystal film with a nanoporosity of 0.10 to 0.15 μm on the sapphire substrate by reacting HCl and NH 3 as a Group III/V mix gas, wherein the method comprises: first reacting HCl and NH 3 as the mix gas in a ratio of 1:220 to 1:280 for 5 to 15 minutes to grow a film of a thickness of 1 to 5 μm; second reacting HCl and NH 3 as the mix gas in a ratio of 1:130 to 1:150 for 15 to 25 minutes to grow a film of a thickness of 1 to 10 μm, thereby forming a nano-porous vertical film with nanoporosity of 0.10 to 0.15 μm; third reacting HCL and NH 3 as the mix gas in a ratio of 1:80 to 1:100 for 20 to 35 minutes to grow a film of a thickness of 1 to 7 μm; treating the film grown by the third reaction of HCl and NH 3 with nitride; treating the film treated with nitride with gallium chloride (GaCl) for 10 to 20 minutes; and repeating the previous second reaction of HCl and NH 3 to form a film to a thickness of 1 to 5 μm, wherein the method further comprises treating the sapphire substrate with gallium chloride (GaCl) at a temperature of 500 to 1,200° C., before the formation of the buffer layer.