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 Γ-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 °C can be used in GeSn, which is much lower than that in Ge (700 °C). Therefore, n-type dopant diffusion in GeSn is suppressed leading to an abrupt n⁺ tunneling junction that is favorable for the source junction of a p-TFET. Lateral Ge_0.958Sn_0.042 p-TFETs were fabricated and high Ion of 29 μA/μm at V_GS = V_DS = -2 V and 4.34 μA/μm at V_GS = V_DS = -1 V is achieved.