Preparation and the growth mechanism of zinc blende structure tin sulfide films by successive ionic layer adsorption and reaction

Zinc blende structure tin sulfide (SnS) films have been prepared by successive ionic layer adsorption and reaction (SILAR) method. It is found that both the annealing and addition of NH4Cl or NaCl to cation solution during the SILAR process can promote the crystallization of SnS films. The growth mechanism for this novel structure considered that the initial distribution of cations on the substrate surface during the cation adsorption process is the crucial factor that determines the structure of the final production. Because Cl− anions can complex with Sn2+ cations, when the concentration of Cl− in the cation precursor solution increases, more [SnCl]+ complex ions are adsorbed on the substrate. These [SnCl]+ ions assemble more orderly than Sn2+ ions because of the polarity of ions, so crystallized SnS films can be obtained when NH4Cl or NaCl is added to the cation solution.