Angular dependence of the in-plane polarization anisotropy in the absorption coefficient of strained M-plane GaN films on γ-LiAlO2

We investigate the in‐plane polarization properties of GaN films grown by plasma‐assisted molecular‐beam epitaxy on LiAlO2(100). Due to the crystal symmetry of LiAlO2(100), GaN films can be realized in a nonpolar (M‐plane) configuration, i.e., the c‐axis of the wurtzite unit cell lies in the growth plane. For strained M‐plane GaN films, the band structure of the valence band changes in such a way that the optical transmittance is completely linearly polarized for two orthogonal in‐plane directions, where one of these directions is parallel to the c‐axis of the GaN film. The transmittance for an arbitrary in‐plane polarization angle can be described as a linear combination of the transmittance for two orthogonal polarization, one of which is parallel to the c‐axis. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)