According to quantum transport simulations, source-to-drain tunneling (SDT) has been recognized as the main cause leading to subthreshold swing (SS) saturation and degradation of short-channel MOSFETs at cryogenic temperatures. Generally, at a given low temperature, the steeper constant SS of thermionic currents may be overwhelmed by less-steep SDT currents at lower gate bias, degrading the average SS. Our simulations show that the SS of SDT currents is insensitive to temperatures for a MOSFET with a given channel length, accounting for SS saturation as lowering temperature. This work reveals the key points differentiating the possible reasons (interface traps, band tail and SDT) of SS saturation at cryogenic temperatures. We also study the impacts of carrier effective masses, gate-SD underlapping and a tunneling barrier at the source junction on SS saturation. SDT may pose a potential challenge and limit for scaling cryogenic CMOS of a quantum processor.

中文翻译：

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低温下源极至漏极隧道效应导致​​纳米级 MOSFET 的亚阈值摆幅饱和


根据量子传输模拟，源极至漏极隧道效应 (SDT) 已被认为是导致短沟道 MOSFET 在低温下亚阈值摆幅 (SS) 饱和和退化的主要原因。一般来说，在给定的低温下，热离子电流的较陡峭常数 SS 可能会被较低栅极偏压下不太陡峭的 SDT 电流所淹没，从而降低平均 SS。我们的模拟表明，对于给定沟道长度的 MOSFET，SDT 电流的 SS 对温度不敏感，将 SS 饱和视为温度降低。这项工作揭示了区分低温下SS饱和的可能原因（界面陷阱、带尾和SDT）的关键点。我们还研究了载流子有效质量、栅极 SD 欠重叠和源极结处的隧道势垒对 SS 饱和的影响。 SDT 可能对量子处理器的低温 CMOS 的扩展提出潜在的挑战和限制。