Electrical properties of pure and (Al, Ga and In) doped CdS/PVA nanocomposites

Abstract

(Al, Ga and In) doped CdS/PVA nanocomposites have been prepared by an in situ chemical method. dc conductivity (σd) measurements of thin films have been done at different temperatures from 288–333 K. The variation of current with voltage is found to be symmetric and linear up to the operating range of the applied voltage. At low temperatures (below 300 K), the conduction mechanism is based on the Davis–Mott model, which involve the presence of localized states originating from a lack of long-range order. In this regime, σ varies exponentially with T−1/4. For high temperatures, conduction is through regular band-type conduction in extended states. From the slope of lnσT1/2 versus T−1/4, we have calculated various Mott’s parameters such as degree of disorder (To), density of states N (Ef), hopping distance (R), and hopping energy (W). The doping of group III elements in CdS/PVA thin films results in a decrease in photoconductivity. Further, n-type conduction behaviour is confirmed in pure and (Al, Ga and In) doped CdS/PVA thin films with Hall measurements. Hall mobility increases with the doping of Ga and In, while it remains almost the same with Al doping in CdS/PVA. Dielectric measurements have also been done to see the effect of frequency at different temperatures (293 K, 313 K and 333 K) and at different applied fields (1 Volt and 3 Volt) on pure and (Al, Ga and In) doped CdS/PVA nanocomposites.