Lateral and Vertical Growth Study in the Initial Stages of GaN Growth on Sapphire with ZnO Buffer Layers by Hydride Vapor Phase Epitaxy

Abstract

ABSTRACTThe initial stage of hydride vapor phase epitaxy GaN growth on ZnO-buffered sapphire is reported. A high supersaturation in the growth ambient was used to favor a rapid initial growth on the substrate. A subsequent step with high lateral growth rate was chosen to promote coalescence of the initial islands and provide optimal material properties. The specific mole fractions of the GaCl and NH3 control these vertical and lateral growth rates. The use of a two- step growth process in the GaN growth has led to improved and controlled morphology and high quality GaN materials have then been grown on sapphire substrate with and without ZnO buffer layers.