A new F(ast)-CMS Algorithm for Efficient Three-Dimensional NEGF Simulations of Arbitrary Shaped Silicon Nanowire MUGFETs

We present here 3D quantum simulations based on Non-Equilibrium Green’s Function (NEGF) formalism using the Comsol Multiphysics™ software and on the implementation of a new Fast Coupled Mode-Space (FCMS) approach. The FCMS algorithm allows one to simulate transport in nanostructures presenting discontinuities, as the normal Coupled Mode-Space (CMS) algorithm does, but with the speed of a Fast Uncoupled-Mode Space (FUMS) algorithm (a faster algorithm that cannot handle discontinuities). Using our simulator, we also show that energy barriers resulting from cross-section variations at the gate edge of a nanowire can be optimized to improve the on/off current ratio. A subthreshold slope steeper than the kT/q.log(10) limit of classical transistors together with symmetrical source drain operation is demonstrated for the first time using this new Variable barrier tunnel transistor (VBT) concept.