Studies on optical and electrical properties of PVA capped nanocrystalline CdSe thin film prepared by chemical bath deposition method

Abstract

PVA-capped nanocrystalline CdSe thin films are deposited on chemically clean glass substrates by chemical bath deposition technique using Cadmium acetate [Cd(CH3COO)2.3H2O and Sodium Selenosulfate (Na2SeSO3) as Cd2+ and Se2- ions sources respectively. Polyvinyl Alcohol (PVA) is act as a capping agent. Films of five different molarities (0.1 M–0.50M) of same pH value 8 were prepared at room temperature 298 K. The characteristics of the prepared CdSe thin films are investigated in detail by measuring their optical and electrical properties. The band gap energy of 2.16–2.49 eV was determined from the optical absorption spectra. The optical band gap decrease with increase in molarities. The electrical conductivity measured using two co-planar Aluminium electrodes are found to increase with increase in temperature showing semiconducting nature of the films. The electrical conductivity at room temperature is found to be of the order of 10-4 Ω-1 cm-1 .