Low Temperature Chemical Precipitation and Vapor Deposition of Sn x S Thin Films

Abstract

Films of gray‐black , brown , and/or were deposited onto nonconductive substrates by (i) an “electroless,” chemical precipitation mechanism in organic baths of , 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 and . 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 deposit/precipitate to smooth surfaces. Mixed phases are often present, as evidenced by x‐ray diffraction, microprobe analysis, and optical absorbance data. Other data, including conductance vs. , photoconductance vs. t, and open‐circuit film voltage in a Sn(II) bath, are presented and proposed film growth mechanisms discussed.