Synthesis, structure and spectro-microscopic studies of polycrystalline HgxPb1−xS thin films grown by a chemical route

The deposition history, growth mechanism, structural, optical and surface morphological features of chemically deposited HgxPb1−xS (0 ⩽ x ⩽ 0.2) thin films prepared under optimized conditions are presented. Effect of growth parameter (x) on the film quality and properties has been studied. The resulting films appeared smooth, uniform and well adherent to the substrate and diffusely reflecting with color changing from grayish-brown to light-brown as x was varied from 0 to 0.2. The EDS analysis showed replacement of Pb2+ atoms from PbS lattice by Hg2+ atoms. The X-ray diffraction revealed crystalline nature with zinc blende type structure with predominant (2 0 0) orientation. Both interplanar distance and lattice parameter for (2 0 0) and (1 1 1) reflections increased with x in the alloyed range (0 ⩽ x ⩽ 0.035). SEM observations showed non-uniform distribution of well defined spherical grains; some of them diffused to form agglomeration/globule like structure. Analysis of the transmission spectra in the 500-3000 nm wavelength range showed 20-95% transmittance, absorption coefficient of the order of 104-105 cm−1 and energy gap increased from 0.52 eV to 1.75 eV respectively for the change of x from 0 to 0.2.