Origin of optical anisotropies of nonpolar GaN surfaces

We investigate the origin of optical anisotropies of the nonpolar GaN (110) and $\left(101\mathrm{}¯0\right)$ surfaces. Using semiempirical tight-binding calculations, we analyze in detail the main optical signature of each surface. The origin of the optical spectra is discussed in terms of the main surface electronic states and of the specific surface atomic rearrangement. Results of the surface dielectric function, and reflectance anisotropy spectra, are presented.