Investigation of Different Si(111) Surface Preparation Methods for the Heteroepitaxy of GaN by Plasma-Assisted MBE

Abstract

The in-situ low temperature preparation of hydrogen passivated Si(111) surfaces has been investigated for GaN growth by rf-plasma source molecular beam epitaxy. The GaN/Si heterostructures were analyzed by transmission electron microscopy, infrared transmittance, photoluminescence (PL) and atomic force microscopy. A silicon nitride layer of 1.5-2.0 nm thickness was formed when GaN was grown directly on a hydrogen passivated Si surface (heated up to 400°C) or on a Si surface with 7 x 7 reconstruction (heated up to 700°C). Growth initiation by Al deposition on a 7 x 7 surface, followed by an AlN nucleation layer, resulted in the best surface morphology and structural quality of 1 μm thick GaN/Si films.