Effect of sulphur doping in SnSe single crystals on thermoelectric power

Single crystals of sulfur doped SnSe with the proportion of SnSe_0.65S_0.35 are grown by direct vapour transport technique. The energy dispersive analysis of x-ray and x-ray diffraction analysis showed the crystals to be stoichiometric and possess orthorhombic unit cell structure, respectively. The surface morphology study of single crystals by scanning electron microscopy showed the growth to have occurred by layer growth mechanism. The optical analysis showed the crystals possess direct and indirect optical bandgaps. The bandgap values are larger than the bandgap values of pure SnSe single crystal. The study of electrical transport properties showed inadequate thermoelectric performance in case of sulphur doped SnSe compared to pure SnSe. The obtained results are discussed in detail. (paper)