Investigation of Structural and Optical Properties of CdS and PbS Doped Materials

Abstract

In the past years, II-IV and II-VI semiconductor materials, deposited in the newlineform of thin films have attracted considerably from the research community, because newlineof their wide range of applications in various technologies and devices. Chemical newlinedeposition technique is an ideal method to obtain low cost thin films, due to its newlinesimplicity and less requirements of additional equipments. newlineIn these studies, mixed base of CdS, (Cd1-xSnx)S, (Cd1-xBix)S and (Cd1-xSbx)S newlinethin films are deposited by chemical bath deposition method at various temperatures newlineand different conditions in water bath. The nanocrystalline PbS, (Pb1-xSnx)S, (Pb1- newlinexBix)S, and Sb doped PbS thin films were deposited on glass substrate at room newlinetemperature at different deposition times. The films were further annealed at higher newlinetemperatures. newlineWith the help of XRD studies the structural parameters of these deposited newlinefilms are calculated. The crystallite size of the films varies with change in doping newlineconcentrations and annealing. Strain and dislocation densities are also found to newlinechange with the variation in compositions of the films. The rms roughness and grain newlinesize are estimated by AFM studies. The SEM micrographs of the films, suggest the newlinelong needle like structure. newlineFrom the results of the optical absorption spectra, the absorption coefficients newlineare evaluated as a function of wavelength. The band gaps of the films are determined newlineby the plots of (and#945;hand#61550;)2 and hand#61550; (Tauc s Plot). The band gaps of the films vary with newlineadding doping concentration and annealing. The band gap of the pure nanocrystalline newlinePbS is found to be 1.8 eV, which is very high in comparison to that of bulk materials newline(0.4 eV). newlinePhotoconductivity studies include the nature of dark current, photocurrent and newlinethe photoconductivity gain with respect to the various preparative conditions. Values newlineof instantaneous life time and mobility of carriers and trap depths are evaluated from newlinerise and decay curves of photoconductivity. With the help of photoluminescence newlineemission spectra the nature of the spectral studie