Low indium content In–Zn–O system towards transparent conductive films: structure, properties and comparison with AZO and GZO

In this work, low content indium doped zinc oxide (IZO) thin films were deposited on glass substrates by RF magnetron sputtering using IZO ceramic targets with the In₂O₃ doping content of 2, 6, and 10 wt%, respectively. The influences of In₂O₃ doping content and substrate temperature on the structure and morphology, electrical and optical properties, and environmental stability of IZO thin films were investigated. It was found that the 6 wt% doped IZO thin film deposited at 150 °C exhibited the best crystal quality and the lowest resistivity of 9.87 × 10⁻⁴ Ω cm. The corresponding Hall mobility and carrier densities were 9.20 cm² V⁻¹ s⁻¹ and 6.90 × 10²⁰ cm⁻³, respectively. Compared with 2 wt% Al₂O₃ doped ZnO and 5 wt% Ga₂O₃ doped ZnO thin films, IZO thin film with the In₂O₃ doping content of 6 wt% featured the lowest surface roughness of 1.3 nm. It also showed the smallest degradation with the sheet resistance increased only about 4.4% at a temperature of 121 °C, a relative humidity of 97% for 30 h. IZO thin film with 6 wt% In₂O₃ doping also showed the smallest deterioration with the sheet resistance increased only about 2.8 times after heating at 500 °C for 30 min in air. The results suggested that low indium content doped ZnO thin films might meet practical requirement in environmental stability needed optoelectronic devices.