This investigation examines the physical mechanisms that can increase the variability of both p-n junctions and silicon–germanium heterojunction bipolar transistors (SiGe HBTs) at cryogenic temperatures. The important operative mechanisms responsible for device parameter variability include bandgap narrowing due to heavy doping, mechanical stress, and the Ge profile. The impact of direct tunneling on cryogenic parameter variability in SiGe HBTs is also examined. Measurement results are compared with TCAD simulations to provide additional insights, and possible mitigation methods are discussed.

中文翻译：

---

低温下pn结和SiGe HBT的变异性

这项研究探讨了在低温下可增加pn结和硅锗异质结双极晶体管（SiGe HBT）变异性的物理机制。负责器件参数可变性的重要操作机制包括由于重掺杂，机械应力和Ge轮廓导致的带隙变窄。还研究了直接隧穿对SiGe HBT中低温参数变异性的影响。将测量结果与TCAD仿真进行比较以提供更多的见解，并讨论了可能的缓解方法。