Quantized Conductance in $\hbox {Ag/GeS}_{2}/\hbox {W}$ Conductive-Bridge Memory Cells

Ag/GeS₂/W conductive-bridge random access memory (CBRAM) cells are shown to program at room temperature to conductance levels near multiples of the fundamental conductance G₀ = 2e²/h. This behavior is not accounted for in the traditional view that the conductance of a CBRAM cell is a continuous variable proportional to the maximum current allowed to flow during programming. For on -state resistances on the order of 1/G₀ = 12.9 kΩ or less, quantization implies that the Ag “conductive bridge” typically contains a constriction, or even an extended chain, that can be as narrow as a single atom. Implications for device modeling and commercial applications are discussed.