Non-volatile memory based on solid electrolytes

Programmable Metallization Cell (PMC) memory utilizes electrochemical control of nanoscale quantities of metal in thin films of solid electrolyte. A silver or copper layer and an inert electrode formed in contact with a Ag ⁺- or Cu²⁺-containing electrolyte film creates a device in which information is stored using large non-volatile resistance change caused by the reduction of the metal ions. Key attributes are low voltage, low current, rapid write and erase, good retention and endurance, and the ability for the storage cells to be physically scaled to a few tens of nm. This paper describes the principle of operation of PMC devices and presents representative results from cells with diameters ranging from micron scale to nanoscale dimensions based on Ag-Ge-Se, Ag-Ge-S, and Cu-WO₃ solid electrolytes.