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Bi 2 S 3 single crystals were grown by the chemical vapour transport technique using ammonium chloride (NH 4 Cl) as a transporting agent. The stoichiometry of Bi 2 S 3 single crystal was confirmed by energy-dispersive analysis of X-rays (EDAX). The powder X-ray diffraction (XRD) pattern showed that Bi 2 S 3 crystals belong to the orthorhombic phase with calculated lattice constant a = 11.14 Å, b = 11.30 Å and c = 3.96 Å. Scanning electron microscopy (SEM) pictures indicate the presence of layer lines on the surface of crystals thereby proving that these crystals are grown by layer by layer mechanism. We studied the transport properties viz. Hall effect, resistivity, thermoelectric power and thermal conductivity on Bi 2 S 3 pellets. Raman spectroscopy and thermal gravimetric analysis (TGA) were carried out on Bi 2 S 3 single crystal for studying their optical and thermal behaviours.

Cadmium selenide (CdSe) thin films were prepared by chemical bath deposition technique on glass substrates using cadmium acetate dihydrate as a source of Cd 2+ ions, and sodium selenosulphate as a source of Se 2ions respectively. Triethanolamine and ammonia were used as complexing and pH controlling agent. Films were deposited at different bath temperatures ranging from room temperature to 80 o C while the pH value was kept constant around 10.50 ±0.10. We determined elemental composition of deposited film by X-ray photoelectron spectroscopy. Optical properties of films deposited at different bath temperatures are studied by absorption spectra and parameters like thickness, band gap and absorption coefficient were calculated from the optical transmission spectra. The optical spectra showed a small blue shift and the band gap was found to be greater than the bulk phase. Raman measurements performed at room temperature using Helium-neon laser and Argon laser confirmed the presence of longitudinal optical phonon modes. The selected area electron diffraction pattern for CdSe thin films indicated that they are having mixed nature i.e. both single crystalline and polycrystalline nature with planes of diffraction rings corresponding to cubic structure of CdSe respectively.