Impacts of O₂/(O₂+Ar) Flow Ratio on the Properties of Li‐Doped NiO Thin Films Fabricated by Pressure‐Gradient Radiofrequency Magnetron Sputtering

Abstract

Herein, Li‐doped NiO thin films are deposited on glass substrates using pressure‐gradient radiofrequency magnetron sputtering, with Ar and O2 as sputtering gases. Following film fabrication, their crystal structures, optical features, and electrical properties are investigated as functions of O2 flow rate to the total flow rate (O2/(O2 + Ar)) of 10 sccm. The deposited films are also annealed at 600 °C for 1 h in an oxygen atmosphere. Notably, the resistivity of the as‐deposited films decreases significantly by three orders of magnitude from 106 to 0.0232 Ω cm when the sputtering gas is changed from pure Ar to pure O2. However, the transmittance decreases with increasing oxygen flow rate. Investigations on the temperature dependence of conductivity reveal hole conduction in the range of ≈320–420 K owing to small polaron hopping.