Structural details of Ge-rich and silver-doped chalcogenide glasses for nanoionic nonvolatile memory

We are reporting our results of Raman and X-ray diffraction (XRD) studies on amorphous Ge ₄₆S ₅₄ thin films and the films after silver photodiffusion. Based on the Raman scattering studies, a structural model for amorphous Ge ₄₆S ₅₄ is suggested including the formation of single Ge-S chains with a vibrational mode at 410 cm ^-1. The result of XRD measurement indicates that there exists a medium-range order with about 6Å even at such Ge-rich composition. After the introduction of silver, the medium-range order is lost and there was a change in the diffraction curve indicative of the change in the local atomic order. The experimental results are explained in terms of our structural model, in connection with the application for fast switching memory devices.