[G-1] Cryo-CMOS

[G-1-01] Substrate Impurity Concentration Dependence of Sub-threshold Swing of Si n-Channel MOSFETs at Cryogenic Tempeartures down to 4 K

〇Min-Soo Kang¹, Kei Sumita¹, Hiroshi Oka², Takahiro Mori², Kasidit Toprasertpong¹, Mitsuru Takenaka¹, Shinichi Takagi¹ (1. Univ. of Tokyo (Japan), 2. National Inst. of Advanced Indus. Sci. and Tech. (AIST) (Japan))

Presentation style: On-site (in-person)

https://doi.org/10.7567/SSDM.2022.G-1-01

The sub-threshold swing (SS) of Si n-MOSFETs is
experimentally and systematically evaluated in a
temperature range of 4 K to 300 K with varying the
substrate impurity concentration (Nsub) from ~1016 cm-3 to
~1018 cm-3, to obtain a physical understanding of SS at
cryogenic temperatures. It is clarified that the
temperature and ID dependencies of SS in n-MOSFETs
are well described by both mobile tail states and localized
interface states, irrespective of Nsub, and that the densities
of these states increase with increasing Nsub. A physical
origin of the tail states is studied by examining the impact
of substrate bias (Vsub) on the tail state width to separate
the effects of substrate impurity concentrations and
electric field. It is found, as a result, that the band tail
states can be explained by the Lifshitz model.