Interface structure and epitaxial growth of M-plane GaN(11̅00) on tetragonal LiA1O2(100) substrates

We report on the atomic interface structure of epitaxially grown hexagonal α-GaN(11̅00) layers on tetragonal γ-LiA1O₂(100) substrates by means of transmission electron microscopy. The novel epitaxial orientation relationship verified by electron diffraction is given by (11̅00)GaN parallel to (100)LiAlO₂ and [112̅0]GaN parallel to [001]LiAlO₂. The interface structure that controls the heteroepitaxial growth is studied by high-resolution electron microscopy. We propose a simple model for the interfacial atomic arrangement, in which strain and chemistry contributions are considered, and we discuss it with respect to the other epitaxial orientation found in the literature for this hetero-system.