Dry etching of GaN substrates for high-quality homoepitaxy

Chemically assisted ion-beam etching (CAIBE) was used to remove subsurface damage from polished GaN bulk substrates prior to growth. Subsequently, GaN layers were deposited by metalorganic vapor phase epitaxy. Only the CAIBE- treated areas reveal a mirror-like surface without trenches, scratches, or holes. A dramatic increase of crystal quality is determined by low-temperat ure cathodoluminescence (CL). Compared to not CAIBE-treated material, the C L intensity is improved by a factor of 1000 and the linewidth is ten times narrower. (C) 1999 American Institute of Physics. [S0003-6951(99)02608-X].