Spectroscopic ellipsometric study of ZnO and Zn1-xMgxO thin films grown on (0001) sapphire substrate

We grew ZnO and Zn1-xMgxO thin films on (0001) sapphire substrates by using metal-organic vapor phase epitaxy and measured the pseudo-dielectric functions using variable-angle spectroscopic ellipsometry. We analyzed the pseudo-dielectric functions by using the multi-layer model. The dielectric functions were fitted by using a Holden model dielectric function. We used anisotropic layer modeling for the ZnO thin film, whereas we adopted the approximation of isotropic layer modeling for the Zn1-xMgxO alloys. We also discuss the Mg composition dependence of the bandgap and the binding energy in Zn1-xMgxO alloys, and consider the valence-band ordering in ZnO thin films.The work of H. Lee was supported in part by the Special Equipment Program of the Korean Basic Science Institute through the Korean Science and Engineering Foundation (KOSEF, R23-2002-000-00006-0). The work of G.-C. Yi was supported by the Advanced Environmental Biotechnology Research Center (No. R11-2003-006)