SELECTIVE GROWTH OF ZINCBLENDE, WURTZITE, OR A MIXED-PHASE OF GALLIUM NITRIDE BY MOLECULAR-BEAM EPITAXY

We report on the growth of GaN with a zinc-blende, wurtzite, or a mixed phase structure on (001)GaP and (001)GaAs substrates by a low-temperature modified molecular beam epitaxy technique. By systematically varying the incident arsenic overpressure, films grown at a moderate substrate temperature of ≈620°C show predominately wurtzite α-GaN, zinc-blende β-GaN, or a mixed phase of the two. Films containing only the metastable phase β-GaN were achieved by using a relatively high growth temperature of ≈700°C and with an arsenic overpressure of ≈2.4×10-5Torr. X-ray diffraction measurements indicate an improved crystalline quality for the layers grown at ≈700°C compared to those grown at ≈620°C as evident by a narrower full width at half-maximum of 35 min for β-GaN, which is among the narrowest reported to date.© 1995 American Institute of Physics.