Structural, surface morphological, optical and thermoelectric properties of sol–gel spin coated Zn doped CdS thin films

摘要

The present work is focussed on Zinc (2, 4, 6, 8 and 10 wt%) doped CdS thin films synthesized by sol–gel spin coatingmethod and deposited on glass substrates. X-ray diffraction patterns of Zn doped CdS thin films exhibit cubic structure.The microstructural properties such as crystallite size, lattice constant, microstrain, dislocation density and stacking faultprobability in the films were reported. The surface morphology and topography of the films was studied by using fieldemission scanning electron microscopy and atomic force microscopy. The incorporation of Zn in CdS and elementalcomposition of the films has been confirmed with X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy(EDS). Raman spectrum of Zn doped CdS thin films exhibits 1LO and 2LO phonon modes. The optical band gapof CdS thin films increased from 2.63 to 2.73 eV with the increase of Zn dopant from 2 to 10%. Thermoelectric powermeasurements show negative Seebeck coefficient indicating n-type semiconducting behaviour. The carrier concentrationof Zn doped CdS thin films at room temperature are found to be in the range of 10~(19)–10~(20) cm~(−3) suggesting that theprepared films are degenerate semiconductors. The increase in thermal conductivity of Zn doped CdS thin film is dueto the increase in carrier concentration of the films. The lattice thermal conductivity of Zn doped CdS thin films had aninverse temperature dependent and at high temperatures shows the dominance of phonon scattering.