Electronic dielectric constants of thermally evaporated SnS thin films

SnS films were deposited on substrates at 300 and 423 K by conventional thermal evaporation technique. The films deposited at 300 K were amorphous in nature and those deposited at 423 K were partially crystalline. The radial distribution function analysis confirmed the layered structure in amorphous and thermally processed films, it also showed that the coordination number of the cation nearest neighbor to the anion is a (1.3 and 3.9) atoms and located at 2.45 and 2.40 Angstrom for amorphous and thermally processed films, respectively. The electronic dielectric constants and behavior were measured by spectrophotometer technique in the wavelength range 250-2500 nm. The lattice dielectric constant of amorphous films increased from 8.84 to 9.68 upon thermal processing, the dispersion energy of amorphous films also increased from 6.76 to 20.28 eV upon thermal processing. The analysis of spectral behavior of dielectric function revealed an indirect forbidden and a direct allowed transitions with energy gaps 1.4 and 2.18 eV for the amorphous films and 1.38 and 2.33 eV for thermally processed films, respectively. (C) 2003 Elsevier B.V. All rights reserved.