Sub-<i>kT/q</i> Switching in Strong Inversion in PbZr_0.52Ti_0.48O₃ Gated Negative Capacitance FETs

Abstract

Hysteretic switching with a sub- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">kT/q</i> steep slope (13 mV/decade at room temperature) is experimentally demonstrated in MOSFETs with PbZr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.52</sub> Ti <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> as a ferroelectric (FE) gate insulator, integrated on a silicon channel with a nonperovskite high- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> dielectric (HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) as a buffer interlayer. The steep switching is independent of drain bias. For the first time, sub- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">kT/q</i> switching due to FE negative capacitance is observed not at low currents, but in strong inversion ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{d}\sim $ </tex-math></inline-formula> 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}/\mu \text{m}$ </tex-math></inline-formula> ). Steep switching in strong inversion provides an important point of consistency with the predictions of the Landau–Devonshire theory and the Landau–Khalatnikov equation.