Growth of M-plane GaN films on γ-LiAlO2(100) with high phase purity

We present a comprehensive study of the growth of GaN(11̄00) on γ-LiAlO2(100) by plasma-assisted molecular beam epitaxy. Pure GaN(11̄00) layers are obtained preferentially on a particular face of the substrate. We provide a means by which to identify this face by simple chemical treatment. Nitridation of the substrate prior to growth as well as immediate N-rich nucleation conditions invariably induce phase mixture. In contrast, immediate Ga-rich nucleation is found to result in the growth of pure GaN(11̄00) films. Layers nucleated at low temperature exhibit the highest structural and morphological quality reported so far for non-[0001]-oriented structures.