SPECTRAL MEMORY OF PHOTOCURRENT IN Cd_1-xZn_xS FILMS DEPOSITED FROM SOLUTION

摘要

Cd_1-xZn_xS films 8-10 μm thick were prepared on glass-ceramic substrates by precipitation from aqueous solutions of thiocarbamide, cadmium and zinc salts, and a complexing agent. Preliminary illumination of the Cd_1-xZn_xS films at a certain wavelength followed by excitation at other wavelengths was found to result in a spike in the photocurrent-decay curve. The spike produced under excitation at 1.36 eV after preliminary illumination at 2.26 eV was considered in detail. The calculated photocurrent-decay curve fits the experimental data well. The spectral memory of photocurrent in the Cd_1-xZn_xS films is due to defects in metastable states. The concentration of these defects can be controlled by varying film composition and preparation conditions.