Growth of GaN on a‐plane sapphire: in‐plane epitaxial relationships and lattice parameters

Abstract We have studied GaN films grown on a‐plane sapphire substrates by both hydride vapor phase epitaxy (HVPE) and metalorganic vapor phase epitaxy (MOVPE). The in‐plane orientation relationships between the epitaxial films and the substrate are determined to be [11–20]GaN ∥ [0001]sapphire and [1–100]GaN ∥ [1–100]sapphire in the HVPE growth, while [1–100]GaN ∥ [0001]sapphire and [11–20]GaN ∥ [1–100]sapphire are found in the MOVPE growth. The different orientation preferences are attributed to the atom termination of the sapphire surface determined by the substrate treatment used in the different growth methods. The effect of the lattice matches on the in‐plane lattice parameters and strain anisotropy in the two cases is studied. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)