Influence of annealing on microstructure and optical properties of hot wall deposited PbxSn(1−x)S thin films

Publication date: Available online 4 October 2016
Source:Thin Solid Films
Author(s): S.A. Bashkirov, V.F. Gremenok, V.A. Ivanov, K. Bente, P.P. Gladyshev, T.Yu. Zelenyak, A.M. Saad, M.S. Tivanov
PbxSn(1−x)S (0.05< x <0.20) thin films with the thickness of 2μm were deposited on glass substrates using hot wall vacuum deposition method at the vacuum pressure of 5×10⁻⁴ Pa, wall temperature of 600°С, substrate temperature of 300°С and subsequently annealed at 450°C in vacuum at 5×10⁻⁴ Pa. The microstructure and optical properties of the as-deposited and annealed films were examined in relation to the film composition. The explanations of lattice parameter deviations from the bulk crystals for both as-deposited and annealed PbxSn(1−x)S thin films are discussed. The PbxSn(1−x)S thin films exhibit a preferred orientation around the [111] direction. The annealing decreases the film microstrain values and increases the grain size and the degree of preferred orientation. Thermal probe measurements showed the sulfur-deficient films to be p-type and the sulfur-rich films to be n-type. The PbxSn(1−x)S films exhibit direct allowed transitions with energy band gap E g(d) increasing with the increase of Pb mole fraction. The E g(d) values for as-deposited films range from 0.95 to 0.98eV and for annealed films they variy from 0.90 to 0.94eV.