An Analytic Model for Heterojunction Tunnel FETs With Exponential Barrier

This paper presents an analytic model for double-gate tunnel FETs with an exponential barrier. By carrying out the Wentzel-Kramer-Brillouin integral in closed form, an I-V model is formulated in terms of a single integral of a continuous function with respect to energy. The model shows that source degeneracy helps the linear region I_ds-V_ds characteristics, but degrades the saturation current. Also investigated is the role of the effective density of states on the debiasing of V_gs due to channel inversion charge at low V_ds. A high effective density of states is shown to lead to superlinear I_ds-V_ds characteristics.