Understanding the conduction mechanism of the chalcogenide Ag2S silver-doped through ab initio simulation

Using first-principles calculations we have investigated the electronic properties of Ag₂S, which is commonly employed as the active matrix in nonvolatile conductive-bridge random access memories (CBRAM). To better understand the origin of the high conductivity of Ag-doped Ag₂S we have created a new model for the high temperature form of this material, with electronic properties in good agreement with the available data. We have found that for a local silver concentration of 7.02 × 10^-4 mol/cm²Ag₂S switches from a semiconductor to a metal, while for a slightly higher concentration of 7.05 × 10^-4mol/cm³Ag₂S forms polytetrahedral clusters within the structure. Our findings offer a consistent explanation for the measured high conductivity of Ag₂S.