Gallium oxide buffer layers for gallium nitride epitaxy

Gallium nitride (GaN) is very attractive semiconductor material because of its unique properties. The serious matter is a lack of easy access to bulk crystals of GaN. Synthesized crystals are precious and rather small. For these reasons almost all device manufacturers and researchers apply alternative substrates for gallium nitride devices epitaxy and it causes that the technology is intricate. Alternative substrates need buffer layers - their technology is usually complex and expensive. We have proposed a simple method to avoid large costs: applying gallium oxide - monoclinic beta-Ga2O3, as the buffer layer, which has structural properties quite good matched to GaN. As the substrates made from single crystal gallium oxide are still hardly available on the market, we have used hydride vapour phase epitaxy (HYPE) GaN epilayers as a starting material. It can be GaN layer under good quality - middle or low. The oxidation process converts top GaN to beta-Ga2O3 layer which can release or absorb the strain. Applying such structure in another, second, epitaxy of GaN allows to obtain good quality epitaxial structures using HYPE technique.