PHOTOINDUCED CHANGES OF THE REACTIVITY OF AMORPHOUS-CHALCOGENIDE LAYERS

The optically induced changes of dissolution rates of AsxS100-x (x = 3 8, 40, 42) amorphous films produced by thermal- or flash-evaporation w ere measured. The fresh-evaporated (as-evaporated) films dissolved mor e slowly than films which were exposed or annealed. We suggest that th e slower dissolution is caused by the poorly soluble 'molecular struct ures' (As4S4, As-4, S-a, S-8), in the films. The dissolution rates of these films can be increased, when cetyltrimethylamonium bromide (CTAB ) or other alkyl-or aryl-ammonium compounds are sorbed onto the chalco genide surface. The Raman spectra revealed that the sorption takes pla ce on As-rich parts of the film. The interaction of sorbed ions with a chalcogenide surface is probably of the Coulomb type. (C) 1997 Elsevi er Science B.V.