Abstract
The authors report on the growth of GaN by nitrogen plasma-assisted molecular beam epitaxy (MBE) on a 2 in. Si (111) substrates with a nanothick (∼4.8 nm thick) γ-Al 2 O 3 as a template/buffer. A thin layer of MBE-AlN ∼40 nm thick was inserted prior to the growth of GaN. High-resolution transmission electron microscopy (HR-TEM) and high-resolution x-ray diffraction studies indicated that both of the nanothick γ-Al 2 O 3 and AlN are a single crystal. Reflection high-energy electron diffraction, high-resolution x-ray scattering using synchrotron radiation, and cross-sectional HR-TEM measurements indicated an orientation relationship of GaN (0002)||AlN (0002)||γ- Al 2 O 3 (111)||Si (111) and GaN [10-10]||AlN [10-10]||γ- Al 2 O 3 [2-1-1]||Si [2-1-1]. A dislocation density of 5× (108-109) cm2 in the GaN ∼0.5 μm thick was determined using cross-sectional TEM images under weak-beam dark-field conditions. © 2008 American Vacuum Society.