The electrical stability of In-doped ZnO thin films deposited by RF sputtering

The electrical stability of transparent conductive oxides is an important criterion for evaluating their performance, especially when they are employed at elevated temperatures or in long-term operation. In this work, indium-doped ZnO thin films with various doping concentrations were prepared by RF sputtering. The electrical properties, electrical thermal stability, and time stability of films with differing indium contents were investigated. The results showed that the degradation of the films’ conductivity is primarily attributable to the reduction in oxygen vacancies at high temperatures under oxygenated conditions. The aggregation of indium atoms, which cannot replace Zn 3+ cations at temperatures above 200 °C, can improve the carrier concentration. Further reaction with oxygen degraded the performance of the films due to the formation of insulating oxides. Long-term analysis showed the IZO films to have quite stable electrical properties. Their conductivity remained almost unchanged after two months at room temperature under normal atmospheric conditions.