Effect of Sb doping in pure phase SnS thin films

Abstract

SnS thin films were fabricated by closed-tube sulfurization of sputtered Sn precursors at temperature range of 200 °C–400 °C. Pure orthorhombic SnS phase with stochiometric composition (S/Sn = 1.03) was obtained at the optimum growth temperature of 250 °C. Hole concentration, resistivity and hole mobility of the as-grown films were found to be 1.3 × 1016 cm−3, 95.5 Ω cm, and 5 cm2 V−1 s−1, respectively. The as-grown film was then Sb doped by thermal diffusion method under controlled Sb vapor pressure. Thermal annealing with Sb improved the crystalline quality of the SnS films. The effects of carrier compensation were observed for Sb concentration greater than 0.55%. Addition of 1.38% Sb results in the electrical resistivity of 5.65 × 104 Ω cm and the carrier concentrations of 1.2 × 1014 cm−3. Activation energy of as-grown sample was 0.20 eV, while that of the sample doped with Sb (1.08%) was 30 meV larger. An increase in mobility with maximum value of 12 cm2 V−1 s−1 was observed for all doped SnS films. However, all doped films were found to keep their p-type conductivity.