Effects of annealing on SnS films produced by chemical bath deposition (CBD)

Tin sulfide (SnS) thin films were produced on glass substrates at 65 degrees C by chemical bath deposition (CBD). Two of the obtained five identical films were annealed in an air atmosphere while the other two were annealed in a nitrogen atmosphere at different temperatures. The effects of annealing (at 150 degrees C and 250 degrees C in air and nitrogen atmospheres) on the optical, structural, and electrical properties of the films were investigated by UV-visible spectrophotometer, x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and Hall-effect measurement. The energy band gap of as-deposited SnS thin film was determined to be 1.16 eV, and it was observed to change with annealing. All of the as-deposited and annealed SnS films had orthorhombic structures. The optical phonon modes to orthorhombic SnS phases were determined by Raman shifts. The carrier type of all SnS films was identified as p-type using Hall measurement, and the changing carrier concentration, mobility, and resistivity values of the films were investigated depending on annealing conditions. The p-type SnS film can be used as an alternative material for the absorber layer in p-n heterojunction solar cell applications.