Modification of the properties of tin sulfide films grown by spray pyrolysis

Abstract

n-Type SnS and SnS₂ sulfide films up to 0.6 μm in thickness, with resistivity in the range 2 ≤ ρ ≤ 17 kΩ cm have been grown by spray pyrolysis of aqueous solutions of the SnCl2 ∙ 2H₂O, SnCl₄ ∙ 5H₂O, and (NH₂)₂CS salts at substrate temperatures in the range 523 ≤ T_s ≤ 623 K. At constant thermal conditions of sulfide film growth, varying the chemical composition of the solutions for spray pyrolysis makes it possible to obtain films with substantially different optical properties. Undoped SnS and SnS₂ have high transmittance, T ≈ 40–70%, and a sharp intrinsic absorption edge. The optical band gap of the SnS and SnS₂ sulfide films has been shown to depend on film growth conditions.