Benchmarking of Homojunction Strained-Si NW Tunnel FETs for Basic Analog Functions

Abstract

This paper reports a compact ambipolar model for homojunction strained-silicon (sSi) nanowire (NW) tunnel FETs (TFETs) capable of accurately describing both I-V and G-V characteristics in all regimes of operation, n- and p-ambipolarity, the superlinear onset of the output characteristics, and the temperature dependence. Experimental calibration on long channel (350 nm) complementary n- and p-type sSi NW TFETs has been performed to create the model, which is used to systematically benchmark the main analog figures of merit at device level: g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> /Id, g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> /g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> , f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> , and their temperature dependence from 25°C to 125 °C. This allows for a direct comparison between 28-nm low-power Fully Depleted Silicon on Insulator (FD-SOI) CMOS node and 28-nm double-gate (DG) TFET. We demonstrate unique advantages of sSi DG TFET over CMOS, in terms of: 1) reduced temperature dependence of subthreshold swing; 2) higher transconductance per unit of current with peaks close to 40 V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , for currents lower than 10 nA/μm; and 3) higher unity gain frequency per unit power for currents below 10 nA/μm.