Microscopic theory of nanostructured semiconductor devices: beyond the envelope-function approximation

Modem electronic and optoelectronic devices are approaching nanometric dimensions where microscopic details cannot be treated in an effective way. Atomistic approaches become necessary for modelling structural, electronic and optical properties of such nanostructured devices. On the other hand, theoretical developments and numerical optimizations make device modelling approachable by atomistic methods. The put-pose of this review is to report on microscopic theories to describe these nanostructured semiconductor devices. Empirical and density functional tight-binding as well as pseudopotential approaches are applied to the study of organic and inorganic semiconductor nanostructures and nanostructured devices. We show how these microscopic methods overcome the limitations imposed by the simplified approaches based on envelope function approximations and in the meantime keep the computational cost low. Typical calculations are shown for one-, two- and three-dimensional confined nanostructured devices, and comparisons with other approaches are outlined.