Patent ID: 7995371

Claim:
A two-terminal memory device, comprising: a two-terminal memory plug having either an unselected state, a half-selected state, or a selected state, the two-terminal memory plug having a first terminal, a second terminal, and including a memory element electrically in series with the first and second terminals and operative to store data as a plurality of conductivity profiles that can be determined by applying a read voltage across the first and second terminals, the memory element operative to reversibly switch between the plurality of conductivity profiles by applying a write voltage across the first and second terminals, a threshold device electrically in series with the memory element and operative to impart a characteristic I-V curve that falls within an operational current-voltage range for data operations to the memory plug, the threshold device operable to configure the memory plug to be in the unselected state, the half-selected state, and the selected state as a function of the operational current-voltage range, the threshold device including a plurality of adjacent tunnel barrier layers that are in contact with each other and are made from a plurality of different dielectric materials, and the memory plug configured to be in the half-selected state by applying a select voltage potential for a data operation to one of its terminals and applying a non-select voltage potential to the other one of its terminals, and wherein the potential difference between the select voltage potential and the non-select voltage potential generates a half-select current in the memory plug.