Conductive transparent films deposited by simultaneous sputtering of zinc-oxide and indium-oxide targets

Abstract Ternary compound oxide films of ZnO–In 2 O 3 system were deposited by simultaneous sputtering of ZnO and In 2 O 3 targets. The target currents of the ZnO and In 2 O 3 target, I Zn and I In , were changed under a constant total current of I Zn + I In . We changed the ratio δ of I Zn to I Zn + I In , that is, δ = I Zn /( I Zn + I In ). At a substrate temperature of 250°C, the film deposited at δ =0.5 was Zn 2 In 2 O 5 in homologous phase and the film resistivity showed a minimum of 300 μΩ cm. The homologous phase of Zn 3 In 2 O 6 was also obtained at δ =0.66, but showed a higher film resistivity than Zn 2 In 2 O 5 . The film deposited at δ =0.3 was a mixture of In 2 O 3 phase and amorphous-like phase and the film resistivity showed another minimum of 300 μΩ cm. At a substrate temperature of 150°C, an amorphous-like film was obtained at δ =0.2–0.5 and a minimum resistivity of 300 μΩ cm was observed. Carrier concentrations from 5×10 20 to 1×10 21  cm −3 due to native donors were observed. In the simultaneous deposition of Zn and In oxides, the Zn atoms seem to take oxygen away from In 2 O 3 bulk through the formation of ZnO. Sticking coefficient of ZnO decreased at a higher substrate temperature above 250°C.