Nanoscale epitaxial overgrowth process and properties of GaN layers on Si (111) substrates

摘要

Nanoscale epitaxial overgrowth has been explored to realize continuous specular GaN films on patterned SiO_2/GaN/Si (111) substrates. We have employed both polystyrene-based nanosphere and interferometric lithographies to form the nanohole array patterns and then subsequent regrowth of GaN is carried out by metalorganic chemical vapor deposition. The nanoscale epitaxial overgrowth process of GaN layers is studied by scanning and transmission electron microscopy measurements. Optical spectroscopic methods such as rnicrophotoluminescence and micro-Raman scattering show an improvement of the optical and crystalline quality in such overgrown GaN layers when compared to GaN simultaneously grown on bulk Si (111) without patterning. Realization of such thicker and good quality GaN layer would be useful to achieve Ill-nitride-based optoelectronic integration on Si substrates.