Highly conducting and transparent Ga$_2$O$_3$ doped ZnO thin films prepared by thermal evaporation method

Amorphous zinc oxide thin films are obtained by thermally evaporating pure zinc oxide powder. Films obtained have an excellent conductivity of 90 $\Omega^{-1}$cm$^{-1}$ with transparency of up to 90% in the visible region. On doping with gallium oxide a great improvement in the conductivity of up to 8.7 · 10$^3$ $\Omega^{-1}$cm$^{-1}$ is observed and the optical band gap of the films is decreased from 3.25 to 3.2 eV, retaining the transparency. Measurements of activation energy show that the doped ZnO film has one donor level at 68 meV and other at 26 meV bellow the conduction band.