Angular dependence of the in‐plane polarization anisotropy in the absorption coefficient of strained M ‐plane GaN films on γ‐LiAlO 2

We investigate the in‐plane polarization properties of GaN films grown by plasma‐assisted molecular‐beam epitaxy on LiAlO 2 (100). Due to the crystal symmetry of LiAlO 2 (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)