Preparation of highly transparent and conducting Ga2O3–In2O3 films by direct current magnetron sputtering

Abstract

Multicomponent Ga2O3–In2O3 films have been prepared by dc magnetron sputtering using targets with a Ga content [Ga/(In+Ga) atomic ratio] of 0–60 at. %. Transparent conducting thin films prepared with Ga contents up to about 40 at. % were identified as Ga-doped In2O3 (In2O3:Ga). A minimum resistivity of 5.8×10−4 Ω cm and a maximum carrier concentration of 5×1020 cm−3 were obtained in an In2O3:Ga film prepared at a substrate temperature of room temperature with a Ga content of 30 at. %. Transparent conducting thin films prepared with a Ga content of 45–50 at. % were identified as a ternary compound: gallium indium oxide, (Ga,In)2O3. The electrical properties exhibited by the (Ga,In)2O3 films were relatively independent of the substrate temperature from room temperature to 350 °C. A sheet resistance of 1–2 kΩ and an average transmittance above 95% were obtained in (Ga,In)2O3 films with a thickness of about 20 nm and prepared with a Ga content of 50 at. %.