A systematic study of the sharp-switching Z2-FET device: From mechanism to modeling and compact memory applications

This paper presents a systematic study of a sharp-switching device built in fully-depleted silicon-on-insulator (FD-SOI) that we have called Z2-FET, as it features zero subthreshold swing (<1 mV/decade of current) and zero impact ionization. The Z2-FET is a compact device with a single front gate that experimentally demonstrates a current ION/IOFF ratio >108 at low supply voltage, as well as gate-controlled hysteresis. The operating principle of the sharp switching involves the positive feedback between carrier flow and gate-controlled injection barriers, as confirmed by TCAD simulations. We discuss the impact of bias and device dimensions on the experimental performance and simulate the Z2-FET’s ultimate scaling capability to <50 nm channel length. We present a simplified compact model of the Z2-FET. With good reliability and relative insusceptibility to temperature variation, the envisioned applications of the Z2-FET include compact, high-speed one transistor DRAM (1T-DRAM), one-transistor SRAM, fast logic and electrostatic discharge (ESD) protection circuits.

► A sharp switching device shows subthreshold swing down to 1 mV/dec and ON/OFF ration up to 108. ► Both experiments and simulation are performed to study its operation principle, scaling capability and reliability. ► A model based on feedback mechanism is built reproducing well the experimental results. ► Thanks to its gate-controlled hysteresis characteristic, the device is used as dynamic and static random access memory with low supply voltage and high access speed.