LOW-TEMPERATURE CHEMICAL PRECIPITATION AND VAPOR-DEPOSITION OF SNXS THIN-FILMS

Films of gray-black Sn//1// minus //xS (E//g approximately equals 1. 0-1. 3 eV), brown Sn//2// plus or minus //xS//3 (E//g approximately equals 1. 6-1. 9 eV), and/or SnS//2// minus //x (E//g approximately equals 2. 1-2. 3 eV) were deposited onto nonconductive substrates by (i) an 'electroless,' chemical precipitation mechanism in organic acid/H//2O baths of SnCl//2, S, and Sn(II)-complexing agents and/or (ii) a novel, above-solution CVD mechanism involving condensation and reaction of Sn and S species such as SnCl//4 and H//2S. H//2O and complexing agent (potassium gluconate or tartaric acid) concentrations critically affect film stoichiometry due to their 'freeing' (with acid ionization) or chelating of the Sn(II). A surface area-minimizing Sn(II,IV)-S(-II) exchange reaction is postulated to explain slow transfer of Sn//xS deposit/precipitate to smooth surfaces.