Raman evidence for the oxidation of amorphous As2(SexS1–x)3 film surfaces under visible light

Abstract

Raman spectra of thermally evaporated As _2 Se _3 and Se-rich (above 50 at. %) ternary As–Se–S films measured at high (above 1 MW cm ^−2 ) excitation power density reveal new narrow peaks emerging during the measurements which are attributed to crystalline arsenolite As _2 O _3 . The latter is formed on the As–Se–S film surface due to thermal decomposition of the film and oxidation of arsenic in ambient air. Contrary to As _2 S _3 , for which the photoassisted oxidation of the film surface requires UV light, for narrower-gap As–Se–S films this effect occurs under illumination by visible light.

Keywords

• amorphous semiconductors
• atomic force microscopy
• Raman spectroscopy
• photochemical reactions
• oxidation