Addition of Sb as a Surfactant for the Growth of Nonpolar a-plane GaN by Using Mixed-source Hydride Vapor Phase Epitaxy

The influence of Sb as a surfactant on the morphology and on the structural and the optical characteristics of a-plane GaN grown on r-plane sapphire by using mixed-source hydride vapor phase epitaxy was investigated. The a-plane GaN:Sb layers were grown at various temperatures ranging from 1000 degrees C to 1100 degrees C, and the reactor pressure was maintained at 1 atm. The atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD) and photoluminescence (PL) results indicated that the surface morphologies and the structural and the optical characteristics of a-plane GaN were markedly improved, compared to the a-plane GaN layers grown without Sb, by using Sb as a surfactant. The addition of Sb was found to alter epitaxial lateral over-growth (ELO) facet formation. The Sb was not detected from the a-plane-GaN epilayers within the detection limit of the energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) measurements, suggesting that Si) act as a surfactant during the growth of a-plane GaN by using mixed-source HVPE method.