Polarization-dependent optical transitions at the fundamental band gap and higher critical points of wurtzite ZnO

The optical properties of wurtzite ZnO are studied theoretically by means of the Empirical Pseudopotential Method (EPM) and by spectroscopic ellipsometry measurements. Based on the calculated polarization-dependent transition matrix elements of wurtzite ZnO, we assign the polarization-dependent contributions to the experimentally determined dielectric function at the fundamental band gap and higher critical points to specific optical transitions at high symmetry points in the Brillouin zone.