Post-growth treatment effects on properties of CuInS₂thin films deposited by RF reactive sputtering

Post-growth treatments, such as annealing, sulfurization, etching as well as ageing, were performed on CuInS 2 films prepared by RF reactive sputtering. Their effects on the structural, optical and electrical properties of the films were studied by means of x-ray diffraction (XRD) and scanning electron microscopy (SEM), optical transmission, and Hall effect measurement, respectively. Heating under vacuum at 500 °C for a certain duration causes recrystallization of the as-sputtered films. The secondary Cu–In phases coexisting in the films sputtered with an insufficient H 2 S flow during sputtering can be eliminated by annealing in H 2 S atmosphere at 500 °C for suitable duration. Meanwhile, the film structural as well as optical properties are enhanced. The electrical properties of the as-grown films changed dramatically with ageing in air, and annealing in vacuum or air. KCN etching removed Cu x S segregations on the film surfaces and returned the film electrical property to its initial state.