Influence of plasma treatments and SnO 2 alloying on the conductive properties of epitaxial Ga 2 O 3 films deposited on C-sapphire by chemical vapor deposition

Ga 2 O 3 thin films, alloyed with SnO 2 , ranging from 0 to 15 at% of Sn in composition, were grown by hot wire chemical vapor deposition on C-oriented sapphire. No conductivity was measured on the as-grown or annealed at 1000 °C samples while UV transparency was high. This contradicts the literature works on the effect of Sn 4+ doping in films obtained by other methods. Besides, X-ray diffraction patterns showed the epitaxial stabilization of a new phase. The films treated by radio-frequency plasma (hydrogen and argon) presented a decrease in transparency and an increase in conductivity. The conductivity also depended on the SnO 2 concentration. The hydrogen doping levels as well as polarons (due to oxygen non-stoichiometry) are suspected to play a role on the conductivity mechanism.