Optical and chemical properties of As–Se and As–S–Se solution processed thin films prepared via As50Se50 source solution modification

Abstract

This work presents the prospect of As–S–Se and As–Se thin film preparation from a modified solution of As₅₀Se₅₀ chalcogenide glass in ethylenediamine. The source solution was modified by direct dissolution of elemental sulfur and amorphous elemental selenium. Using this method, we successfully prepared four sulfur-modified (As₄₅S₁₀Se₄₅, As₄₀S₂₀Se₄₀, As₃₅S₃₀Se₃₅, and As₃₀S₄₀Se₃₀) and four selenium-modified (As₄₅Se₅₅, As₄₀Se₆₀, As₃₅Se₆₅, and As₃₀Se₇₀) solutions. Thin films of all compositions (including unmodified As₅₀Se₅₀) were deposited in specular optical quality using spin coating. The structure, composition, organic residue content, refractive index, optical band gap, surface roughness, and chemical resistance of thin films were studied depending on the annealing temperature. The obtained data suggest the incorporation of both sulfur and selenium into the glass structure already in the solution, which resulted in changes of the optical and chemical properties of thin films. According to our observation both composition and proximity to stoichiometric composition have a major impact on the optical and chemical properties of the studied thin films. The solution modification allows easy preparation of thin films with multiple different compositions from a single source solution.