Atomistic Full-Band Simulations of Si Nanowire Transistors: Effects of Electron-Phonon Scattering
Date of this Version2009
An atomistic full-band quantum transport simulator has been developed to study three-dimensional Si nanowire field-effect transistors (FETs) in the presence of electron-phonon scattering. The Non-equilibrium Green's Function (NEGF) formalism is solved in a nearest-neighbor sp(3)d(5)s* tight-binding basis. The scattering self-energies are derived in the self-consistent Born approximation to inelastically couple the full electron and phonon energy spectra. The band dispersion and the eigenmodes of the confined phonons are calculated using a dynamical matrix that includes the bond and angle deformations of the nanowires. The optimization of the numerical algorithms and the parallelization of the NEGF scheme enable the investigation of nanowire structures with diameters up to 3 nm and lengths over 40 nm. It is found that the reduction of the device drain current, caused by electron-phonon scattering , is more important in the ON-state than in the OFF-state of the transistor. Ballistic transport simulations considerably overestimate the device ON-currents by artificially increasing the charge injection mechanism at the source contact.
Nanoscience and Nanotechnology