Investigation of different Si(111) surface preparation methods for the heteroepitaxy of GaN by plasma-assisted MBE

摘要

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 7×7 reconstruction (heated up to 700°C). Growth initiation by Al deposition on a 7×7 surface, followed by an AlN nucleation layer, resulted in the best surface morphology and structural quality of 1 μm thick GaN/Si films.