A TEM study of substrate pitting during the MBE growth of GaN on GaAs and GaP substrates

When epitaxial GaN is grown on (001) and View the MathML source oriented GaAs and GaP substrates by MBE, pits are found to develop in the substrate. Complementary cross-sectional and plan view transmission electron microscopical observations confirm the crystallographic nature of these voids which are considered to form by sourcing of Ga from the substrate during the first stages of epitaxy.