Patent ID: 7621998
Filing Date: 2009-11-24
Classification: C30B,H01L

Abstract:
1. A method of preparing a freestanding, single crystalline gallium nitride (GaN) film comprising the steps of: i) growing a heavily Si-doped GaN film on a substrate to a thickness of 20 to 50 μm using a hydride vapor phase epitaxy (HVPE) process, to induce the formation of cracks on the film; ii) cooling the substrate/heavily Si-doped GaN laminate obtained in step i) to propagate the cracks to the bottom of the substrate; iii) growing a GaN film on the crack-containing substrate/heavily Si-doped GaN laminate obtained in step ii) using an HVPE process; and iv) removing the crack-containing substrate and heavily Si-doped GaN layer from the crack-containing substrate/Si-heavily doped GaN/GaN film composite obtained in step iii) to obtain the GaN film, wherein the single crystalline gallium nitride film has a crystal tilt angle of C-axis to <0001> direction per surface crystal distance of 0.0022°/mm.