THIN AND SUPERTHIN PHOTOCONDUCTIVE CDSE FILMS DEPOSITED AT ROOM SUBSTRATE-TEMPERATURE

Low conductive and photosensitive CdSe films were deposited on substra tes at room temperature. X-ray diffraction spectra showed a microcryst alline cubic structure for film thicknesses greater than 20 nm and an amorphous structure for film thicknesses below 10 nm. An optical band gap, E(g)0, of 1.6 eV was determined using the Tauc-dependence usually employed for amorphous semiconductors. The dark conductivity, sigma, of 10(-9) OMEGA-1 cm-1 was measured in the as-deposited state, but an increase of five orders of magnitude was observed after heating the la yer above 450 K. High photosensitivity was observed under illumination with white light as well as with monochromatic light over a wide spec tral region (400-750 nm). A conclusion is reached concerning the exist ence of compensated donor and acceptor defects in the as-deposited sta te.