Electrical, optical and morphological properties of chemically deposited nanostructured HgS–Bi 2S 3 composite thin films

Abstract

(HgS) x (Bi 2S 3) 1− x ternary composite semiconducting thin films have been successfully prepared by chemical bath deposition technique. The bath compositions include: mercuric chloride (HgCl 2), bismuth nitrate (Bi(NO 3) 3·5H 2O), sodium thiosulphate (Na 2S 2O 3·5H 2O), distilled water and ethylenediaminetetraacetic acid (EDTA), which served as a complexing agent. The colour of the deposits changed from whitish-brown to deep brown as the composition parameter x, was varied from 1 to 0. The films were characterized by X-ray diffraction (XRD), optical microscopy, optical absorption, and electrical resistivity measurement techniques. The dc electrical conductivities were measured in the temperature range 328–433 K. The resistivity and activation energy are found x dependent. The optical absorption measurements were carried out in the wavelength range 350–1100 nm to investigate dependence of bandgap energy of (HgS) x (Bi 2S 3) 1− x on x.