Simulation of direct source-to-drain tunnelling using the density gradient formalism: Non-Equilibrium Greens Function calibration

Quantum mechanical confinement effects, gate, hand-to-hand and source-to-drain tunnelling will dramatically affect the characteristics of future generation nanometre scaled devices. It has been demonstrated already that first-order quantum corrections, which satisfactorily describe quantum confinement effects, can be introduced into efficient TCAD orientated drift-diffusion simulators using the density gradient approach. In this paper we refer to Non-Equilibrium Green's Function simulations in order to calibrate the density gradient formalism in respect of both confinement and source-to-drain tunnelling using different effective masses in directions normal and parallel to the conducting channel. We demonstrate that the density gradient formalism can describe accurately the current characteristics in sub 20 nm double gate MOSFETs.