Effectively Suppressed Short-Channel Effects in Small-Size MoS<sub>2</sub> Transistors by Introducing Negative-Capacitance Effect Resulted From Ferroelectric HfZrO<sub>2</sub> Film
Jiyue Zou, Xiao Zou, Lu Liu, Hongjiu Wang, Jing-Ping Xu
Abstract
Few-layered molybdenum disulfide (MoS2) negative-capacitance field-effect transistors (NCFETs) with an Al2O3/HfZrO2 (HZO) gate stack and various channel lengths ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {CH}}{)}$ </tex-math></inline-formula> were prepared, and the influences of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {CH}}$ </tex-math></inline-formula> on device performances including short-channel effects (SCEs) were investigated. The MoS2 NCFETs with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {CH}}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.2~\mu \text{m}$ </tex-math></inline-formula> exhibit excellent subthreshold characteristics: a minimal subthreshold swing (SS) of 28 mV/dec and an average SS of 45% lower than that of the baseline devices with the same <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {CH}}$ </tex-math></inline-formula> , a greatly reduced average drain-induced barrier lowering (DIBL) (50 mV/V) to a quarter of the baseline devices, and a small hysteresis voltage below 80 mV. The relevant mechanisms lie in that the negative-capacitance (NC) effect of HZO results in a low SS, the negative differential resistance (NDR) effect of the NCFETs leads to a suppressed DIBL, and a reasonable capacitance matching between dielectric capacitance and ferroelectric capacitance realizes a small hysteresis. Statistics show excellent consistency and repeatability for the electric performance of the NCFETs, and the relevant results will be of a great significance to suppressing SCEs for ultrashort-channel NCFETs in the future.