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The ordinary optical dielectric functions of pulsed-laser-deposition grown wurtzite c-plane MgxZn1−xO (0≤x≤0.53) thin films have been determined by using spectroscopic ellipsometry in the photon energy range from 4.5 to 9.5 eV. The dielectric functions reveal features which resemble those previously detected in uniaxial AlGaN and identified as E1- and E2-type band-to-band transitions with no remarkable dependence of the transition energy on Mg content x. The E1- and E2-type transitions for ZnO are compared with pseudopotential band-structure calculations. [Copyright &y& Elsevier]

Generalized infrared spectroscopic ellipsometry for wave numbers from 370 to 1200 cm−1 was applied to study the anisotropic dielectric response of wurtzite-type ZnO thin films grown on r-plane sapphire. Combined wavelength-by-wavelength analysis of data measured at multiple sample in-plane orientations allows for simultaneous extraction of the dielectric function (DF) tensor, the film thickness and the respective ZnO c-axis orientation, specifically in relation to the sapphire substrate. For anisotropic materials and use of generalized ellipsometry, the correlation problem between thickness and DF does not exist. Subsequent line shape analysis of ordinary and extraordinary DFs provides complete A1- and E1-symmetry longitudinal and transverse optical phonon-mode and broadening parameters, together with the static dielectric constants. The epitaxial relations from the ellipsometry data analysis are (1 1 −2 0)ZnO∣∣(0 1 −1 2)sapphire and [0 0 0 1]ZnO∣∣[0 −1 1 1]sapphire, which was confirmed by XRD measurements. [Copyright &y& Elsevier]