Electronic structure of semiconductor nanowires

We compute the subband structure of several group IV and III-V 001 -, 110 -, and 111 -oriented nanowires using s p3 and s p3 d5 s* tight-binding models. In particular, we provide the band gap energy of the nanowires as a function of their radius R in the range R=1-20 nm. We then discuss the self-energy corrections to the tight-binding subband structure, that arise from the dielectric mismatch between the nanowires (with dielectric constant εin) and their environment (with dielectric constant εout). These self-energy corrections substantially open the band gap of the nanowires when εin > εout, and decrease slower (1/R) than quantum confinement with increasing R. They are thus far from negligible in most experimental setups. We introduce a semi-analytical model for practical use. This semianalytical model is found in very good agreement with tight-binding calculations when εin > εout.