Chemical bath deposition of SnS films with different crystal structures

SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or orthorhombic structure which is determined by the pH value of the deposition solution (zinc blende structure at pH = 5 and orthorhombic structure at pH = 6). The reason for this result may be that SnS films prepared at different pH values have different deposition mechanisms, which results in different structures. The prepared SnS films are all smooth and well adhered. The optical bandgaps of the SnS films are determined to be 1.75 eV and 1.12 eV for zinc blende structure and orthorhombic structure, respectively.