The IHP virtual substrate project focuses today on the integration of functional GaN layers on the Si material platform via oxide buffer layers by heteroepitaxy [1-6].
In order to achieve single crystalline (0001) oriented GaN films on Si(111) substrates a patented bi-layer buffer is used. By applying Sc2O3/Y2O3 buffers the 17% lattice mismatch between GaN and Si can be reduced by 50% to about 8% (lattice mismatch between GaN and Sc2O3) GaN/Sc2O3/Y2O3/Si(111) heterostructures are prepared by Molecular Beam Epitaxy (MBE) and characterized by various in-situ and ex-situ techniques.
Molecular Beam Epitaxy at IHP: “proof of principle”
A 4” MBE cluster system is installed at IHP Materials Research department. It is composed of separated but in-situ interconnected oxide, SiGe, III-V and UHV-CVD chambers with a number of in-situ characterization tools (various RHEED systems, XPS & UPS). As MBE is a highly flexible research thin film deposition method, it is widely employed in the current GaN project for “proof of principle” studies of innovative materials science approaches. In the course of these studies, special emphasize is devoted to develop a fundamental understanding of the solid state physics of GaN heteroepitaxy processes on innovative oxide buffer approaches on Si(111).
