A Physics-Based Model of Vertical TFET—Part II: Drain Current Model

Abstract

A physics-based model for the tunneling current of vertical tunneling field transistors (TFET) is proposed. In part I, the expression of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi _{\text {1D}}{(}\textit {x}{)}$ </tex-math></inline-formula> is derived from the multi-branch general solutions of Poisson’s equation. The model’s results are verified with TCAD simulation for transistors with different materials, device geometries, and biases. In this article, a surface potential model is validated at different device regions which include channel and drain. Based on the above two electric potential models, Kane’s tunneling formula is utilized for the calculation of band-to-band tunneling current. The proposed current model is valid for all transistors’ operating regions. The quantum effect on the band-structure parameters is taken into account in the modeling of InAs vertical TFET. It is shown that the channel thickness needs to be optimized to achieve the highest drive current.