Indium doping induced modification of the structural, optical and electrical properties of nanocrystalline CdSe thin films

Abstract

Nanocrystalline thin films of CdSe:In 1% and CdSe:In 5% are prepared by thermal evaporation using the Inert Gas Condensation method. The effects of different doping concentrations of In have been investigated. X-ray diffraction, optical absorption, Photoluminescence (PL) and electrical techniques are used to characterize the films. X-ray diffraction measurements indicate that the nc-CdSe:In 1% and nc-CdSe:In 5% thin films possess hexagonal structure. The crystallinity of the films and the grain size decreases as the In doping concentration increases. The results of PL measurements indicate that the PL intensity decreases as the In doping concentration increases. The optical band gap values increase as the In doping concentration increases. The dc electrical conductivity increases from undoped nc-CdSe to nc-CdSe:In 1% and decreases for nc-CdSe:In 5%. The density of the states near Fermi level N(EF), degree of disorder (To), hopping distance (R) and hopping energy (W) near the Fermi level are calculated using dc conductivity measurements at low temperatures. The effect of In doping concentration on these parameters is discussed. Hall measurements are performed on nc-CdSe, nc-CdSe:In 1% and nc-CdSe:In 5% to calculate the carrier concentration, carrier type and mobility of charge carriers.