Formation of photosensitivity in CdSexTe1-x monograin powders

Formation of photosensitivity in CdSexTe1-x (x greater than or equal to 0.4) monograin powders and the influence of simultaneous doping with copper and oxygen to dark- and photoresistivity of these materials have been studied. The best conditions for receiving high photosensitivity were found to be different for materials with x = 1 and with x < 1. For CdSe these ones were 700-750 degrees C and [Cu] = (3-6)x10(-4) mole Cu/mole CdSe while for CdSe0.4Te0.6 they were 450 degrees C and (5-7)x10(-5). There was found a narrow region of Cu concentrations where the acceptor effects of oxygen and copper were additive, i.e. the same levels of RU have been gained if the sum of oxygen and copper concentrations remained constant. The observed changes in photoconductivity of CdSe due to the simultaneous doping with copper and oxygen were in correlation with changes in photoluminescence (PL) spectra. The peak positions (1.33 eV for the k-band and 1.06 eV for the r-band) and half-widths of these PL bands remained constant. The ratio of the intensities of the k- and r-PL-bands I-k/I-r had tendency to increase with increasing oxygen concentration showing changes in the defect concentrations responsible for the k- and r-PL-bands of CdSe or changes in recombination parameters of these centers.