Heat treatment of bias sputtered ZnO films

The effect of a post-deposition heat treatment on the electrical and optical properties of RF sputtered ZnO films has been investigated in detail. The resistivity can be varied by several orders of magnitude and optimum values are obtained for films heated at ≈ 420°C for 5– 10 minutes in a hydrogen atmosphere. This treatment is also required in order to stabilize the as-sputtered films against Oxygen chemisorption. An optical transmission, larger than 80%, and a sharp absorption edge, (equivalent to an energy gap of 3.3 eV) independent of sample condition, were observed in all cases.