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 ci tratocadmium(II) or tartratocadmium(II) complex ions and N, N-dimethyl selenourea. 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 depositio ns were made at room temperature. The films are uniform and adherent t o glass substrates. The as-prepared films are only marginally photosen sitive with a photocurrent to dark current ratio of < 10 under white l ight 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 duratio n and temperature of annealing. The photocurrent rise and decay time a re short, typically of the order of milliseconds. The combination of f ilm thickness, annealing temperature and duration of annealing that pr esents the best photosensitivity for the films is discussed.