Characterization of vacuum evaporated PbS thin films

The narrow gap lead chalcogenides and related solid solutions have been the materials of considerable technological importance. Their unusual and unique characteristics make them a preferred subject for solid state research and development. The high quality polycrystalline thin films of PbS have been deposited onto ultra-clean glass substrates by vacuum evaporation technique. The as-deposited films were annealed in vacuum at 350 K. The optical, electrical and structural investigations on PbS thin films have been carried out. The optical band gap and optical constants (absorption coefficient, refractive index and extinction coefficient) of the films were determined by absorbance and transmittance measurements using Fourier transform infrared spectrophotometer. The DC conductivity and activation energy of the films were measured in temperature range 300-380 K. The schottky junction of PbS with indium was made and the barrier height and ideality factor were determined using current-voltage characteristics. The sample quality, crystal structure and lattice parameter of the films were determined from X-ray diffraction pattern. (C) 2002 Elsevier Science B.V. All rights reserved.