Modification of electrical, optical and crystalline properties of chemically deposited CdS films by thermal diffusion of indium and tin

Abstract

In a recent work we reported that chemically deposited intrinsic CdS thin films can be converted into n-type with an electrical conductivity of ∼ 10 2 −1 cm −1 by solid state diffusion of indium at temperatures of 300-350 • C from a thin film of indium deposited by thermal evaporation on the CdS surface. In the present study, we report on the enhancement of grain size accompanying this diffusion process and its correlation with a reduction in the optical bandgap. X-ray powder diffraction patterns show that the typical grain size, ∼ 13 nm, of the as-deposited CdS film of 150 nm thickness increases to about 17 nm when the CdS-In film is heat treated at 350 • C for 1 h. There is a corresponding decrease in the optical bandgap from 2.58 eV (as-prepared) to 2.37 eV (heat treated CdS-In). The heat treatments of CdS only and CdS-Sn films have also led to an increase in the electrical conductivity by a factor of 10 8 and a reduction in the bandgap, but with little effect on grain size.

Influence of films thickness and structure on the photo-response of ZnO films

“…where I light and I dark are the currents measured under illumination and in the dark, respectively [32]. As can be seen in Fig.…”

Effect of annealing and composition on crystal structure, surface morphology and optical absorption of chemically deposited Cd1‐xSnxS films

“…Freshly deposited thin films contain many defects such as voids, pinholes etc. [16]. In order to obtain films with stable structure, after deposition the films were subjected to a heat treatment at 400 °C for 2 min in the furnace.…”

Changes of the structural and optical properties of cubic CdS films on annealing in H2and air atmospheres

“…This obstruction favours the generation of V Cd -I Cd pairs in a larger density than in the case of S 2 presence, giving rise to the volume of microcrystallites increasing [14]. Thermal annealings in air and O 2 ambients [15,16] and, consequently, raising the volume of the material a little more than in the case of H 2 ambient [14]. The volume increase in CdS by the V Cd -I Cd pairs is not always a monotonically increasing function: at TTA = 450 • C a saturation is initiated similar to the saturation observed in the volume increase in the Ar + S 2 ambient [14].…”