Modeling of an optically controlled FET

In recent years, the GaAs IC fabricated from Schottky gate field effect transistor (MESFET) have emerged as a promising technology for the development of high speed digital circuits. Optically controlled characteristics of the FET have been analyzed by singh etal which was used as a dual gate switching or memory device. The first gate used as a virtual gate where light is incident and another is the real gate where the bias is being applied. The present paper deals the modelling of in optically controlled GaAs FET. The basic physics behind above device is that when optical radiation is incident on the transparent or semitransparent GaAs, the electronhole pairs are generated just below the gate within the gate depletion region, resulting the changes in the relevant parameters of the device. However, the traps present at the surface recombine via deep traps reduces the device performance. The results present the design criteria for such device in terms of trap center density either at or close to the surface of the GaAs material and the diffusion effect. The device is also observed to be useful either as a power device or switching device in addition to the detecting device.