The formation of cubic GaNAs phase during the growth of thin GaNAs epilayers on GaN at low temperatures by metalorganic chemical vapor deposition

Abstract

20 nm GaNAs epilayers were grown on GaN/sapphire by metalorganic chemical vapor deposition. As growth temperature decreased from 720 to 565°C, it was found that As concentration was increased from 1.3 × 1020 and saturated at about 5-6 × 1020 cm-3. GaAs-like GaNAs islands were formed on GaN at 530°C. In case of GaNAs epilayers grown at 565 and 600°C, GaN-like GaNAs phases were observed by high-resolution X-ray diffraction (XRD) and low angle XRD. By low angle XRD and high-resolution TEM with electron nano-beam diffraction patterns, the FCC-stacked region in wurtzite matrix was clearly observed in thin GaNAs layers. We propose that this structural nonuniformity in GaNAs might be caused by the nonuniform distribution of As concentration.