Selective growth of zinc-blende, wurtzite, or a mixed phase of gallium nitride by molecular beam epitaxy

Abstract

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 ≊2.4×10−5 Torr. 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.