A nonlocal approach for semianalytical modeling of a heterojunction vertical surrounding-gate tunnel FET

A semianalytical model based on a nonlocal approach is proposed for an undoped tunnel field-effect transistor (TFET) with a vertical surrounding-gate structure. The heterostructure band alignment is computed by applying the affinity rule on suitable potential expressions obtained from the two-dimensional (2-D) electrostatic solution for all device regions. The fringing field, doping-induced degeneracy, ambipolarity, and dual modulation effects are included with the aim of obtaining a large domain of validity. The core model is completed with expressions for the capacitance of the terminals and validated against numerical simulations obtained using ATLAS-2D software. An investigation of the types of band alignment and the impact of doping on the device performance is also conducted. The developed models could be implemented into commercial simulators to investigate circuits based on such multigate field-effect transistors (FETs).