Metalorganic Chemical Vapor Deposition Growth of GaN Using a Split-flow Reactor

Abstract

We developed a split-flow reactor for growing epitaxial films in an atmospheric metalorganic chemical vapor deposition (MOCVD), where the reactant gas stream is separated from the wall by a buffer gas stream. This reduces the use of reactant gases, thereby minimizing operating costs. Wall deposits were also minimized. The reactor was fan-shaped with an inclined upper wall. To reduce the interdiffusion of the reactant and buffer streams, the substrate was placed upstream, near the gas inlet. The downward inclined upper wall maintains a constant cross sectional area and therefore constant velocity in the radial direction. The result is that the flow is stabilized. We demonstrated this reactor by growing undoped GaN epitaxial films on a two-inch substrate using a two-step growth process, where the epitaxial layer is grown on a buffer layer. The highest quality GaN films were grown using a buffer stream of H2, but the lowest consumption of the reactant gases was achieved using a buffer stream of N2.