Abstract
Chalcogenide materials which can be used in the development of electrical memory were studied in the course of this work. The aim was to improve our knowledge of the materials and of the mechanisms that could explain the electrical switching. The study was not focused on the crystalline/amorphous phase change phenomena involved, for example, in the stoechiometric material Ge2Sb2Te5 (GST) at the basis of the development of PC-RAM (Phase Change Random Access Memory). We rather focused on the electrical switching phenomena which can be used in the development of R-RAM memories (Resistive Random Access Memory). Two kinds of materials were studied: Ag-Ge-Se compounds selected to develop "programmable metallization cell" and Ge2Sb2+xTe5 compounds containing an excess of antimony as compared to the GST phase change material. First, a structural and electrical investigation of the active material Agx(GeySe1-y)100-x as a bulk glass and as a thin film was carried out, mainly on the basis of characterization by near field microscopy and Raman spectroscopy. Then, the electrical switching in thin films was investigated with a new method: the conductive atomic force microscopy (C-AFM). The same technique allowed investigating the electrical switching phenomena in thin films prepared by sputtering Ge2Sb2+xTe5 (x = 0.25, 0.5, 1) targets.