Novel Oxide Buffer for Scalable GaN-on-Silicon

Abstract

An alternative approach for growing GaN-on-Si using a hybrid epitaxial process, in which the rare-earth oxide buffer is first optimized with the template then used in a standard upstream MOCVD epitaxial process, is demonstrated. Using a rare earth oxide as the buffer layer the most obvious benefit is the spatial separation of the GaN from the silicon which removes one of the key breakdown paths. The oxide epitaxial process is robust and scalable to 200 mm diameter wafers. Combining oxides with different lattice spacings into ternary alloys enables the formation of graded and stacked layers starting from a lattice coincident material at the silicon surface to an upper surface that is now only 9% mismatched from GaN, as opposed to 17% for GaN on silicon. The suitability of the oxide within an MOCVD process has been demonstrated by the growth of bulk GaN using a standard sapphire like process.