An Analytical Drain Current Model for the Cylindrical Channel Gate-All-Around Heterojunction Tunnel FETs

In this paper, we present analytical models which are valid in all regions of operation and can accurately predict the potential profile and the output, as well as the transfer characteristics of the gate-all-around heterojunction tunnel field-effect transistors. Our potential model takes into account the charge carriers in the channel, as well as the space charges in the depletion regions of the two reservoirs. Later, this potential model is utilized to calculate the band-to-band tunneling generation rates at any spatial coordinate in the tunneling volume. Next, these rates are integrated over tunneling volume to find the total tunneling current. This leads to an analytical model for the drain current. We validate our models against the data obtained via numerical simulations for several common heterojunction tunnel devices at various geometries and bias conditions.