Theoretical Limit of MOSFET Subthreshold Swing at Sub-Kelvin Temperatures

2024/10/11 by Arnout Beckers, Beckers, Arnout
Engineering · #Advancements in Semiconductor Devices and Circuit Design #Semiconductor materials and devices #Low-power high-performance VLSI design

paper · pdf · doi:10.48550/arxiv.2410.09276

Abstract

Fully conductive band tails cause the subthreshold swing to saturate at temperatures above 1 K. However, recent measurements indicate that below 1 K, the subthreshold swing in certain MOSFET structures resumes a linear scaling with temperature. Following this ultra-steep behavior, a new type of plateau has been measured below 1 K. In this letter, we show that hybrid band tails, with both traps and mobile states, explain this new plateau. Furthermore, hybrid band tails explain various non-saturating behaviors above 1 K. Remarkably, for entirely non-conductive band tails, the simulations and theory predict a third type of plateau below 10 mK. We hypothesize that this represents the lower bound of subthreshold swing at sub-Kelvin temperatures, which is a testable prediction from the theory.

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