The electrical and optical properties of Cu-doped In₂O₃ thin films

To study the effect of Cu doping, In₂O₃ and Cu-doped In₂O₃ films were deposited on K9 glass and Si substrates with the same experimental parameters. All the films were found to be body centered cubic and have the same preferred orientation. No secondary phases were detected in Cu-doped In₂O₃. The atomic ratio of Cu to Cu plus In was approximately 18% in Cu-doped In₂O₃ films which were found to be n-type. After Cu doping, the resistivity of the films increased by 3 to 4 orders of magnitude and the film with higher Cu content had larger resistivity, due to compensation. Cu doping is found to widen the optical band gap of In₂O₃ films, possibly due to a metal–insulator transition. - Highlights: • Cu doping changes neither the structure nor the preferred orientation of the films. • Cu doped In₂O₃ are n-type. • Cu doped In₂O₃ films have much larger resistivity than undoped In₂O₃. • Cu doped In₂O₃ films have larger optical band gaps than undoped In₂O₃