Understanding quantum transport in a Ge-Si semiconductor core-shell nanowire transistor

Semiconductor core-shell nanowires are one-dimensional radial heterostructures composed of different semiconductor material in the core and shell. Energy band offsets between the core and shell part provides a unique opportunity to modulate carrier transport in these nanowires making them ideal candidates for designing field effect transistors (FETs). Experimental measurements have shown high-performance behavior in a Ge-Si semiconductor core-shell nanowire FET (Xiang et al., Nature, 2006, v. 441, 489); the scaled transconductance and on current values in these transistors are reported to be three to four times higher than that of state-of-the-art MOSFETs. Key to understanding the high-performance behavior of this transistor requires a first principles approach that does not make any assumptions on the charge, electronic structure and potential profile of the device. Herein, using a quantum transport approach, we have unraveled the most probable tunneling pathway for electrons in a Ge–Si core-shell nanowire FET with orbital level spatial resolution (Jaishi et al., Nanoscale, 2017, v. 9, 13425) that explains the observed transistor characteristics.