Influence of substrate impurity concentration on sub-threshold swing of Si n-channel MOSFETs at cryogenic temperatures down to 4 K

作者：Min-Soo Kang, Kei Sumita, Hiroshi Oka, Takahiro Mori, Kasidit Toprasertpong, Mitsuru Takenaka, Shinichi Takagi · 发表于：Japanese Journal of Applied Physics · 年份：2023 · DOI：10.35848/1347-4065/acb362 · 被引用次数：20 · 研究领域：Semiconductor materials and devices、Advancements in Semiconductor Devices and Circuit Design、Silicon Carbide Semiconductor Technologies

Abstract The sub-threshold swing (SS) of Si n-MOSFETs is experimentally and systematically evaluated in a temperature range of 4–300 K with varying the substrate impurity concentration ( N sub ) from ~10 16 to ~10 18 cm −3 , to obtain a physical understanding of SS at cryogenic temperatures. It is clarified that the temperature and drain current dependencies of SS in n-MOSFETs are well represented by a model composed of mobile tail states and localized interface states, irrespective of N sub . The densities of these states are found to increase with increasing N sub . A physical origin of band tail states is studied by experimentally examining the impact of substrate bias on these states, which can separate the effects of the N sub and the surface electric field. It has been clarified, as a result, that the band tail states can be explained by the impurity-induced model.