Nanoporous GaN templates were fabricated by electrochemical etching to give hexagonal pits with nanoscale pores of 20 to 50nm in the underlying grains. The effect of GaN buffer layer grown at 650 to 1015C on these as-fabricated nanopores templates was investigated by transmission electron microscopy. The buffer layer grown at the optimized temperature of 850C partially fill up the pores and voids with annihilation of threading dislocations, serving as an excellent template for high-quality GaN growth. This phenomenon is, however, not observed for the samples grown with other temperature buffer layers. Micro-Raman measurements showed significant strain relaxation and improvement in the crystal quality of the overgrown GaN layer on nanoporous GaN template as compared to overgrown on conventional GaN template.

Dislocation Annihilation in Regrown GaN on Nanoporous GaN Template with Optimization of Buffer Layer Growth. C.B.Soh, H.Hartono, S.Y.Chow, S.J.Chua, E.A.Fitzgerald: Applied Physics Letters, 2007, 90[5], 053112 (3pp)