Heteroepitaxy of Cubic GaN

Abstract

We report on the epitaxial growth and the microstructure of cubic GaN. The layers investigated are deposited by plasma-assisted molecular beam epitaxy on GaAs (001) and (311)A substrates. Transmission electron microscopy reveals that, despite of the extreme lattice mismatch between these two materials, GaN grows in the metastable cubic phase with a well-defined orientation-relationship to the substrate and a sharp heteroboundary. This preference of the metastable phase and its epitaxial orientation originate in the initial stage of growth which is discussed in connection with a coincidence lattice for the investigated interface structures.