  In the present work, we have investigated the performances of L shaped
Vertical broken bandgapheterostructureInSb InAsn-channel tunnel field effect
transistors TFETs of 4 nm thin channel structures with the gate lengths of
20nm. We have used a 3D full band, quantum mechanical simulator based on
atomistic sp3d5s spin-orbital coupled tight binding method.In this L shaped
nonlinear geometry the gate electric field and tunnel junction internal field
are oriented in same direction. A broken narrow bandgap BG structure has
another advantage that transport is by mixture of electrons holes. TFETs are
promising devices for lowpower logic design due to low subthreshold swing SS
and high Ion Ioff ratio. We investigate current voltage characteristics, ON
current OFF current andsubthreshold swing as function of equivalent oxide
thickness, gate length, drain length, gate undercut, High K, and drain
thicknessfor L shaped nonlinear geometry tunnel FET for low subthreshold swing
and lowvoltage operation. To study 2D electronic transport in this L shaped
nonlinear geometry we used Non Equilibrium Green Function NEGF based quantum
transport method using sp3d5s tight binding model in which Poisson-Schr odinger
solver self consistently iterates to obtain potentials and Local Density of
States LDOS. The advantage of this method is that it can handle arbitrary
geometries and complicated 2D structures like Band to Band tunnelling BTBT
devices. NEGF quantum transport method gives output in terms of Poisson
potential and space charge in 3D, energy resolved transmission and spectral
function and Local Density of States of electrons holes in space and energy.
