Effects of impurity scattering on electron-phonon resonances in semiconductor superlattice high-field transport

A nonequilibrium Green’s function method is applied to model high-field quantum transport and electronphonon resonances in semiconductor superlattices. The field-dependent density of states for elastic ~impurity! scattering is found nonperturbatively in an approach which can be applied to both high and low electric fields. I-V curves, and specifically electron-phonon resonances, are calculated by treating the inelastic ~LO phonon! scattering perturbatively. Calculations show how strong impurity scattering suppresses the electron-phonon resonance peaks in I-V curves, and their detailed sensitivity to the size, strength and concentration of impurities.