Device physics and design of a L-shaped germanium source tunneling transistor

A novel tunneling field-effect transistor (TFET) with an L-shaped Ge source is investigated. The device comprises a Ge source that extends underneath a Si-channel region and separated from the drain by an insulator (SiO ₂). By optimizing the overlap length of the extended source L _OV and the Si body thickness T _Si, the current due to vertical band-to-band tunneling (BTBT) of the Ge-Si hetero-junction could be increased significantly and is scalable with L _OV. This leads to higher I _ON and improved S. The SiO ₂ also reduces OFF-state current I _OFF by blocking leakage paths. With extensive simulation, the device physics and design guidelines of this novel structure are outlined.