Synthesis and characterization of zinc tin sulphide (ZTS) thin films via chemical bath deposition route

Zinc Tin Sulphide (ZTS) thin films were deposited on glass substrates by Chemical Bath Deposition (CBD) technique. The CBD was obtained by preparing 20 ml of 0.5M of Zinc chloride solution, 20ml of 0.5M stannum chloride (SnCl2) with 3ml of Triethanolamine (TEA) (N(CH2CH2OH)3) and 25ml of 0.5M of Thiourea as complexants. The grain size of ZTS from the SEM micrographs was spherically-shaped without visible defects like crack or peel. The SEM micrograph of the annealed ZTS thin films, however, showed a dense sponge-like structure. ZTS thin films reflectance curve exhibited average reflectance below 30% for all films. Annealed ZTS thin films (at 200 0C) exhibited the greatest reflectance of about 30% than all other films. Both as-deposited and annealed ZTS films exhibited transmittance above 40% for wavelength around 780 nm and above. The extrapolated band gaps energy values for ZTS for as-deposited and annealed thin films varied from the range of 3.30 to 3.40 eV. The resistivity increased with an increase in heat treatment and it ranged between, 1.83 × 10-1 Ωm to 9.71 × 10-2 Ωm