Efficient quantum modeling of inelastic interactions in nanodevices

International audienceThis paper presents an efficient direct quantum method to model inelastic scattering in nanoelectronic structures including degenerate band extrema. It couples the Born series expansion of the nonequilibrium Green's function (NEGF) to an analytic continuation based on the Pade approximant technique. Using a two-band k . p Hamiltonian, we analyze the electron transport through a linear chain in the presence of both optical and acoustic phonons. Results are consistently compared with the usual, computationally expensive, self-consistent Born approximation (SCBA). We find that our approach provides a much better convergence for both types of phonons in the presence of strong multiband coupling. The calculation of the current to the fifth order in the interactions is sufficient to reproduce the influence of all considered phonon interactions. We also show that the method can be applied to the calculation of the density of carriers which depicts however a slower convergence rate than the current. The capability to efficiently calculate both current and carrier density represents a clear advantage in a context of increasing request for atomistic quantum simulations