Photoconductivity and defect levels in ZnxCd1−xSe with (x=0.5, 0.55) crystals

Gold surface barriers on Zn_xCd_1−xSe alloys have been investigated for composition with x=(0.5, 0.55). The electrical characteristics were studied as a function of air annealing. The common feature of all the Schottky devices was the reduction of reverse bias leakage current after heating in air. Typical measurements of capacitance as a function of bias voltage can provide information on the charge density and diffusion potential. The barrier height was found to increase after air annealing at 200°C for 2 min. The spectral response of the photocurrent and photocapacitance associated with these device layers enable a donor level at 0.13 eV and acceptor levels at 1.08, 1.3 and 1.45 eV below the bottom of the conduction band to be identified. The results are discussed in terms of the effects of oxygen absorption.