Surface-potential-based metal-oxide-semiconductor field-effect transistor compact model with localized states down to 4.2 K toward cryogenic applications

Abstract

This paper presents a new surface-potential-based cryo-MOSFET compact model that incorporates multiple carrier sources and remains valid across a wide temperature (T) range from 300 K down to 4.2 K. By explicitly accounting for doping concentration, incomplete ionization, and localized states, a unified analytical surface potential expression is derived via Schroder series. The proposed model captures the T-dependent variation of charge transport under cryogenic conditions and introduces the concept of an effective temperature (Teff), achieving excellent agreement with experimental data. In addition, key cryo-T device behaviors, including drain-induced barrier lowering, subthreshold-slope (SS) saturation, time-dependent reliability (i.e., bias-temperature-instability), and high electric-field (E) induced kink, are accurately reproduced. Furthermore, 6T-SRAM cells with different W/L configurations are analyzed and simulated at 300, 77, and 4.2 K. The results show significant improvements in both the read and write static noise margins at 4.2 K, demonstrating the potential applicability of this compact model for basic cryo-circuit design, particularly in applications where localized-state-induced non-idealities are prominent, such as in peripheral circuitry for quantum computing systems.