Vital role of Ar ambient pressure in controlled properties of nanocrystalline CdS thin films

Abstract

A report on the manipulation of structural, optical, and electrical properties of nanocrystalline CdS (ncCdS) thin films in the framework of varying Ar ambient pressure in pulsed laser deposition (PLD) is presented here. Increase in Ar ambient pressure results in reduction of crystallite size which in turns increases the structural imperfections and structural phase transformation of ncCdS thin films. The most significant observation here is the bleaching of multiphonon Raman modes (MRMs) particularly LO + 2E2, 2LO + 2E2, etc. in ncCdS thin films. An acute investigation on the reason of bleaching of LO + 2E2, 2LO + 2E2, etc. modes is carried out here and concluded that it is due to the fading of E2 mode with increasing Ar pressure as confirmed by low-frequency micro-Raman measurements. UV–visible absorption and photoluminescence spectroscopies are used to examine the optical properties like bandgap and possible electronic transitions in ncCdS thin films. Further, transport properties of ncCdS thin films are investigated using Hall measurement and I–V characteristics.