Optical constants of titanium-doped gallium oxide thin films

Abstract

This study explores the effect of titanium (Ti) doping on the optical constants of nanocrystalline gallium oxide (Ga2O3) films (GTO). Co-sputtering of the Ga2O3 and Ti targets with a variable sputtering power to Ti allowed the fabrication of GTO films with a variable Ti-content from 0 to ∼5 at%. The optical constants, namely index of refraction (n) and extinction coefficient (k), and their dispersion profiles determined indicate that the n profiles are sensitive the Ti content while all the GTO films were transparent. The n values at 632 nm varies in the range of 1.78–1.84 due to gradual increase of Ti concentration from 0 to 5%. Lorentz-Lorenz analysis of the optical constants data indicates the gradual improvement in the packing density coupled with structural transformation accounts for the observed optical quality of the Ti-doped Ga2O3 films as a function of Ti concentration. A correlation between the material composition, Ti concentration and optical constants is discussed.