Preparation of highly photosensitive CdSe thin films by a chemical bath deposition technique

Thin films of CdSe were deposited by a chemical bath technique from citratocadmium(II) or tartratocadmium(II) complex ions and N, N-dimethylselenourea. The final thicknesses of the films were 0.17 mu m from the citrate bath and 0.28 mu m from the tartrate bath, when the depositions were made at room temperature. The films are uniform and adherent to glass substrates. The as-prepared films are only marginally photosensitive with a photocurrent to dark current ratio of < 10 under white light of intensity 2.1 kW m(-2). Annealing the films in air for 30 min-2 h at 300-450 degrees C results in high photosensitivities, 10(3)-10(7), depending on the film thickness, bath composition, and the duration and temperature of annealing. The photocurrent rise and decay time are short, typically of the order of milliseconds. The combination of film thickness, annealing temperature and duration of annealing that presents the best photosensitivity for the films is discussed.