GaN nanostructures and HFET structures selectively grown on silicon substrates by ammonia-MBE

Abstract

Silicon substrate can be used as a highly effective pseudomask to perform selective growth of GaN by ammonia molecular beam epitaxy (MBE). This can be exploited to fabricate novel photonic and electronic device structures on Si substrates. Growth of GaN micro-pyramids as templates for fabricating InGaN quantum dots, and growth of AlGaN/GaN HFET mesa patterns using the selective growth approach is reported. The facet growth characteristics of the selectively grown GaN micro-pyramids are investigated. μ-photoluminescence (μ-PL) measurements resolving emissions from InGaN quantum dots and/or wells on a single GaN pyramid have been performed, but have found no evidence of formation of InGaN single quantum dot at the apex of the GaN pyramid. Possible improved growth approaches for achieving such single quantum dot structures are discussed. Success in selective growth of the HFET mesa pattern and especially the insulating carbon-doped GaN buffer layer is achieved, demonstrating a promising approach for potential integration of nitride devices with silicon circuits.