Inversion of absorption anisotropy and bowing of crystal field splitting in wurtzite MgZnO

摘要: The anisotropic optical properties of wurtzite MgxZn1−xO thin films (0≤x≤0.45) grown on m-plane ZnO substrates by plasma assisted molecular beam epitaxy are studied using spectroscopic ellipsometry at room temperature. data analysis provides the dielectric functions for electric field polarizations perpendicular and parallel to axis. splitting between absorption edges two polarization directions decreases x = 0 x = 0.24, while an inverted anisotropy is found higher Mg content, indicating a sign change crystal Δcr as spin orbit parameter. characteristic energies such exciton binding band gaps determined from imaginary parts functions. In particular, these reveal bowing parameter b=−283 meV describing compositional dependence indicate Δcr=−327 meV MgO. valence ordering (...