Photo and Thermally Induced Absorption Bands in Very Thin a-As₂S₃ Films

Abstract

Optical darkening and thermal bleaching of very thin a-As₂S₃ films with 80±10 nm thickness have been investigated. A new absorption band with a half height width of 1.37 eV peaking at 3.32 eV occurs by illumination on the films with ∼3 eV or ∼4 eV photons at 80 K. The thermal behavior of this band is almost identical with that of the shift of the absorption edge in thick films reported by others. Another new band with a half height width of 1.95 eV peaking at 3.63 eV is produced by thermal annealing of the film showing the 3.32 eV band up to about 440 K. Possible optical and thermal kinetics to understand the results are discussed.