Local electrical characterization of Ag conducting chalcogenide glasses using electric force microscopy

Local electrical properties of Agx(Ge0.25Se0.75)100 − x glasses with x = 5, 15, 20 and 25 at.% were investigated by electric force microscopy.The EFM contrasts electrically evidenced phase separation in these glasses with a percolation of a Ag-rich phase at the origin of a sudden jump in conductivity for x = 8–10 at.%.A method to obtain information about the electrical permittivity, through a simple modelled electrical circuit, is described in detail. The use of the model helped in showing a continuous increase in the permittivity of each present phase (Ag-rich phase and Ag-poor phase) when the silver content in the glasses increased. The result, in turn, indicates that both phases have their composition that changes when more silver is added to the Ge–Se backbone. This result departs from previous assumptions of a constant composition for the Ag-rich phase.