Doping and annealing effects on ZnO:Cd thin films by sol–gel method

In this article, ZnO:Cd films were successfully deposited on glass substrates by a sol–gel technique. The influence of doping concentration and annealing temperature effects was carefully investigated. All films exhibited c-axis preferential orientation and optical transparency with visible transmittance >80%. The minimum room temperature resistivity of 0.0341 Ω cm was obtained with 10 at.% Cd doping under 600 °C annealing temperature. The optical band gap of ZnO:Cd film was reduced as Cd doping concentration increased, while the band gap increased with the increase of annealing temperature.

Research highlights
► Sol–gel derived ZnO:Cd thin film exhibits c-axis preferential orientation even if Cd doping concentration reaches up to 30%. Meanwhile, the room temperature resistivity does not decrease monotonously with the increase of Cd doping concentration.