Investigation of Optimal Photosensor in A-Si:H Liquid Crystal Light Valves

Abstract

The a-Si:H thin film is used for a photosensor in liquid crystal light valve (LCLV). A lumped element model for the layered a-Si:H LCLV is developed. It has been shown that the dark and photoresistances of the a-Si:H photosensor should be adjusted respectively to within the region between one order of magnitude higher and one order of magnitude lower than that of the liquid crystal(LC) layer to ensure a linear variation of the voltage across the LC with the intensity of the incident write-light beam. For obtaining an optimal operation condition of the LCLV, we can determine the concrete values of the dark resistance of the photosensor from the threshold voltage of the LCLV for the linear change of the LCLV's grey level and the applied voltage of the LCLV, and the photoresistance of the photosensor from the saturation voltage of the LC. As a result, the application of an a-Si:H film by optimization of the deposition condition indicates that the contrast of LCLV can be improved distinctively.

Opto-Electronic Properties of MBE-Grown ZnSSe Thin Films on ITO Substrates

“…These three elements connected in series are shown in Figure 5 [7], with R LC and C LC representing the resistance and capacitance of the liquid crystal layer, while R M and C M represent the resistance and capacitance of the dielectric mirror, respectively. Usually, it is required that R M R P , so it can be proved [8] that at d.c. operation (f = 0), the voltage drop across the liquid crystal layer, V LC , under a total applied bias V b is given by…”