Steep-Slope IGZO Transistor Monolithically Integrated with Initialization-Free Ag/Ti/Hf0.8Zr0.2O2 Atomic Threshold Switch

Abstract

A steep-slope In-Ga-Zn-O (IGZO) field-effect transistor (FET) monolithically integrated with an Ag/Ti/Hf_0.8Zr_0.2O₂ atomic threshold switch (ATS) device is presented, which allows switching below the Boltzmann limit of 60 mV dec⁻¹ at room temperature (25 °C). The low-temperature processable IGZO FET is combined with the Hf_0.8Zr_0.2O₂-based ATS device, which featured initialization-free and low-voltage switching, to achieve an ultra-low power device solution with back-end-of-line process compatibility (≤400 °C). To further assess the potential of the ATS-IGZO FET devices for circuit applications, they are applied to logic and memory integrated circuits. Inverter ring oscillator simulations are performed to investigate the relationship between switching speed and power consumption. In addition, static random-access memory simulations are performed to verify that ATS-IGZO FETs can achieve a stable noise margin along with low standby power consumption. This comprehensive evaluation provides an in-depth assessment of the applicability of ATS-IGZO FETs for ultra-low power logic and memory applications, highlighting their potential for substantial performance improvements.