ABSTRACTA brief summary is given of the characterization of an optically addressed Spatial Light Modulator (SLM) that uses a thin film of CdS as the hhotosensor and a liquid crystal as the electro-optic material. The required ghdark impedance of the CdS thin film is achieved by a depletion region created by surface acceptor states. Analysis of the SLM complex impedance as a function of frequency and illumination indicates that the voltage switching is due to the reduction in impedance with illumination caused by the increased capacitance of the CdS thin film. The impedance measurements as well as photoluminescence data were consistent with an acceptor surface state model accounting for the depletion region of the CdS thin fim. Additionally the SLM is shown to exhibit photoelectrochemical cell characteristics such as dark rectification, and a photocurrent and photovoltage proportional to the illumination intensity. The SLM performance characteristics of good resolution and sensitivity is attributed to the surface state induced depletion region.
