Theses and Dissertations Collection

This dissertation presents the research on the synthesis of ZnO based ternary semiconductor alloy films with tailored band gaps and the studies in their structural and optical properties. Mg_xZn_1-xO alloys expanded the band gaps from 3.20 eV to deeper UV region of 5.67 eV. While ZnS_xO_1-x reduced the band gaps into the visible region of 2.9 eV. The alloy films were grown via reactive sputtering deposition, which is a cost effective and environment-friendly

technique. An analytical method was developed for accurately determining the band gaps of alloys via transmission spectroscopy. The structural inhomogeneity issues in the Mg_xZn_1-xO alloys were studied via Selective Resonant Raman Scattering. Urbach energy analysis and Raman spectral line width analysis indicated that structural defects and alloy composition fluctuations in the Mg_xZn_1-xO alloy films are the dominant origins of the localized electronic

tail states and the Raman line broadening. While the Raman line broadening due to the anharmonicity of the alloys is not significant. The achievement of ZnS_xO_1-x alloy films with reduced band gaps paved the way for further research on band gap engineering of ZnO in the visible region.