Cross-Coupled Gated Tunneling Diodes With Unprecedented PVCRs Enabling Compact SRAM Design—Part I: Device Concept

Abstract

Tunnel diodes (TDs) and resonant tunneling diodes (RTDs) with negative differential resistance (NDR) have attracted interest in implementing high-density, low-power circuits, such as static random access memory (SRAM). However, the low peak-to-valley current ratios (PVCRs) in these devices cause high static leakage currents, leading to poor performance in the circuits and limiting their application. This article presents a novel device, i.e., a cross-coupled gated tunneling diode (XTD), that exhibits NDR with PVCRs exceeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{5}}$ </tex-math></inline-formula> . The device design is validated by TCAD simulation as well as an experimental demonstration. In contrast to conventional TDs, which operate in the forward bias direction, the XTD operates in the reverse bias direction, thus suppressing thermionic emission and trap-assisted tunneling (TAT) currents, which together allow for the large PVCR. In Part II of this article, we continue to discuss compact, low-power SRAM cells based on the XTD.