Performance variability in wrap-round gate silicon nano- transistors: a 3D self-consistent NEGF study of ballistic flows for atomistically-resolved source and drain

A recently developed 3D self-consistent Non-equilibrium Green Function technique is used to study technologically identical silicon wrap-round gate 3D nanowire devices each of which has a different atomistically-resolved spatial distribution of dopants in the source and drain but in the absence of inhomogeneities in the channel/oxide interface and for an undoped channel. The simulations broadly confirm the conclusions of an earlier theoretical study of granularity effects on drive current that was limited by being two-dimensional and used a strongly inhomogeneous but continuum model of the doping profile in source and drain. However, the 3D nature of the flows makes it easier for charge to re-distribute around the regions of strong attractive potential. The stronger inhomogeneity effects in current density and charge density and the large inter-device variability predicted by 2D models are therefore over-estimates.