Effects of deposition parameters of low-temperature GaN layer on the structural and optical properties of cubic GaN epilayers grown on GaAs(001) substrates by MOVPE

Effects of low temperature (LT-) GaN insertion on the cubic (c-) GaN thin film growth by metalorganic vapor phase epitaxy were investigated. Approximately 8-10-nm-thick LT-GaN were found to be essential for the growth of the c-GaN overlayer to prevent the films from peeling off from GaAs substrates and from the hexagonal GaN inclusion. When the LT-GaN was thinner than 8 nm, good quality c-GaN was obtained although distinct voids were formed at the c-GaN/GaAs interface. From the cross-sectional transmission electron microscopy (TEM) observation, lateral growth over the voids was found.