NUCLEATION CONTROL IN THE GROWTH OF BULK GAN BY SUBLIMATION METHOD

Nucleation of GaN crystallites by sublimation method on sapphire (0001 ), scratched sapphire (0001), SiO2, on Si (111), and metalorganic chem ical vapor deposition(MOCVD)-GaN/sapphire (0001) was investigated. The density of the nuclei on SiO2 and Si (111) was estimated to be 6 x 10 (3)/cm(2). On the other hand, a continuous film rather than discrete c rystallites tvas obtained on both the MOCVD-GaN and the scratched sapp hire. Growth nucleation control was performed by partly covering the M OCVD-GaN or scratched sapphire (0001) with SiO2. As a result, hexagona l columns about 200 mu m in diameter and 200 mu m high were selectivel y and uniformly grown at the window sites. The diameter of each hexago nal column nas much larger than the width of each window. This method can be used for device processing utilizing the crystallites.