Germanium-tin p-channel tunneling field-effect transistor: Device design and technology demonstration

We report the demonstration of germanium-tin (GeSn) p-channel tunneling field-effect transistor (p-TFET) with good device performance in terms of on-state current (I-{on}). With the incorporation of Sn, the conduction band minima at \Gamma-point of GeSn alloy shift down, increasing the direct band-to-band tunneling (BTBT) generation rate at the source-channel tunneling junction in TFET. In addition, n-type dopant activation temperature of below 400^{\circ}{\rm C} can be used in GeSn, which is much lower than that in Ge (700^{\circ}{\rm C} ). Therefore, n-type dopant diffusion in GeSn is suppressed leading to an abrupt {\rm n}⁺ tunneling junction that is favorable for the source junction of a p-TFET. Lateral {\rm Ge}-{0.958}{\rm Sn} _0.042 p-TFETs were fabricated and high I_on of 29 \mu{\rm A}/\mu{\rm m} at V-{\rm GS}=V-{\rm DS}=-2~{\rm V} and 4.34 \mu{\rm A}/\mu{\rm m} at V-{\rm GS}=V-{\rm DS}=-1~{\rm V} is achieved.