Photoinduced anisotropy in the ion-conducting amorphous semiconductor Ag–As–S

Amorphous Ag–As–S films become birefringent and their surfaces are modified when exposed to linearly polarized light. The photoinduced birefringence is positive with a magnitude of +0.01, which is in contrast with that (−0.001) of As2S3 . The refractive index change appears with an anisotropic surface deformation, which consists of two kinds of patterns. One is fringes in an illuminated spot and the other is streaks as catʹs whiskers radiating from the spot. Compositional measurements show that the fringe accompanies an Ag-content modification of ∼5 at.%. The photoinduced anisotropy in Ag–As–S films is assumed to be caused by photo-electro–ionic interaction.