Photoconductivity of Thin Film Semiconductor as Compared to that of Bulk Semiconductor

Abstract

In this study, the photo response of gallium antimonide (GaSb) thin film and bulk material is investigated under different conditions. First, with the aid of the principle of the illumination mechanism, the photon absorption rate as a function of absorption coefficient and depth below the illuminated surface in both the bulk and the thin films of GaSb were determined. Next, using the steady state condition of the free carriers generationrecombination mechanism, the radiative excess carrier lifetime of the photo-generated free carriers is described in both thin films and the bulk material as function of the depth below the surface, doping levels, injection levels and absorption coefficient. The obtained result indicates that, photon absorption rate and the free carrier’s generation rate in general increases with decreasing the thickness of the thin films. The photo-response of the thin film semiconductor is found to be in general dominated by the property of the surface depletion layers of the material and hence extremely higher than the photo-response of the deep bulk.