Kinetics of the thermally and photoinduced solid state reaction of Ag withAs33S67 films

The kinetics of the solid state chemical reaction of silver with amorphous As33S67 films in a conventional sandwich structure was measured by opticall y monitoring the change in thickness of the undoped chalcogenide. For the t hermally stimulated process, the kinetics data indicate a two-stage process , with the second stage having a sublinear time dependence. The effect of b roadband illumination is to reduce the activation energy by approximately o ne order of magnitude, but the photoinduced process still has two identifia ble stages. In the case of the photostimulated process, rate coefficients a nd activation energies have been measured and the composition and structure of the reaction products have been determined by Rutherford backscattering spectroscopy (RBS). The RBS spectra obtained at different stages of the ph otoinduced reaction process show a step-like form for the Ag concentration profile during the course of the reaction and indicated a homogeneous distr ibution of Ag in the final reaction products, the Ag concentration being 19 .5 at. %. (C) 2000 American Institute of Physics. [S0021-8979(00)07811-7].