MOCVD Growth and Characterization of Be-Doped GaN

Beryllium has been considered a potential alternative to magnesium as a p-type dopant in GaN, but attempts to produce conductive p-GaN:Be have not been successful. Photoluminescence studies have repeatedly shown Be to have an acceptor level shallower than that of Mg, but deep Be defects and other compensating defects render most GaN:Be materials n-type or semi-insulating at best. Previous reports use molecular beam epitaxy or ion implantation to dope GaN with Be, almost exclusively. Due to the high toxicity of Be organometallics, reports of GaN:Be by metal-organic chemical vapor deposition (MOCVD) have been largely absent. Here, we report a systematic study of growth of GaN:Be by MOCVD. All doped samples show the established UV band and yellow luminescence signature of GaN:Be, and growth conditions resulting in high-quality GaN with stable Be incorporation were established. Our results show that the MOCVD growth technique allows for Be incorporation pathways that have not been possible with previous growth methodologies and is highly promising in achieving p-type conductivity in GaN:Be.