Influence of low temperature thermal annealing on the dark resistivity of chemical bath deposited CdS films

CdS thin films were grown by chemical bath on glass substrates and exposed to different annealing atmospheres over the range of temperatures 200–350°C. Electrical, structural and optical properties as well stoichiometry of the films were investigated. Large changes on resistivity as a function of annealing temperature, and a limited temperature region yielding films with very low resistivity were found. Resistivity values as low as 0.05 Ω cm are attained at the interval of temperature 240–260°C in H2 atmosphere. Resistivity values exhibit sharp increase in the region 260–300°C as a result of the film-stoichiometry change on account of Cd evaporation.