Orders of magnitude reduction in dislocation density in GaN grown on Si (111) by nano lateral epitaxial overgrowth

摘要

Nanoscale laterally epitaxial overgrown (NLEO) GaN layers were investigated on Si (1 1 1) substrate. Nanoporous S1O_2 films on the surfaces of GaN/Si (111) were fabricated by in-ductively coupled plasma etching using anodic alumina tem-plates as etch masks. GaN was grown over the nanoporous SiO_2 layer using metalorganic chemical vapor deposition. Supersaturation of the source material was investigated to realize a continuous and smooth film. NLEO GaN layers were found to result in a significant reduction of threading dislocation density ～10~8cm~(-2), characterized by atomic force microscopy and cross-sectional transmission electron microscopy. High quality GaN nanorod arrays has also been demonstrated and investigated on Si (111) substrates. Nanoscale over-growth is a promising method to improve the quality of GaN semiconductor materials for the commercialization of GaN devices on Si substrates.