Memory Select Devices

Abstract

Crossbar arrays are important for high-density memory design, which is particularly suitable for emerging memories with two-terminal structures. A key enabler for crossbar arrays is functional two-terminal select devices. Select devices utilize either asymmetry or nonlinearity to reduce sneak leakage in crossbar arrays. This chapter reviews numerous two-terminal select devices broadly divided into three groups: diodes, volatile switches, and nonlinear devices. Recent progress in these groups of devices is summarized, based on a set of benchmark parameters. Self-selecting memories based on self-rectifying or intrinsic nonlinear characteristics are also discussed. Select devices still face great challenges to meet high-density array requirements; however, significant progress has been made recently. Functional select device solutions for large crossbar arrays may become available in the near future.