Role of Arsenic Hexagonal growth-suppression on a Cubic GaNAs Growth using Metalorganic Chemical Vapor Deposition

The hexagonal domain suppression-effects in cubic-GaNAs grown by metalorganic chemical-vapor deposition (MOCVD) is reported. A thin buffer layer (20 nm) was first grown on a substrate at 853 K using trimethylgallium and dimethylhydrazine (DMHy), and GaNAs samples were grown at different AsH 3 flow rates (0 ∼ 450 μmol/min) at 1193 K. As a result, three types of surface morphologies were obtained: the first was a smooth surface (AsH 3 = 0 μmol/min); the second was a mirrorlike surface having small and isotropic grains (AsH 3 : 45 ∼ 225 μmol/min ); and the third involved three-dimensional surface morphologies (above 450 μmol/min of AsH3 flow rate). Furthermore, it was confirmed using X-ray diffraction that the mixing ratio of hexagonal GaNAs in cubic GaNAs decreased with an increase of the AsH 3 flow rate. We could obtain GaNAs having a cubic component of above 85% at AsH 3 flow rates above 20 μmol/min. Therefore, the MOCVD growth method using AsH 3 and DMHy was mostly effective for suppressing hexagonal GaNAs. It was observed that the photoluminescence intensity of GaNAs was decreased with increase of arsine flow rate.