Vertical screening in doped, intentionally disordered semiconductor superlattices

The energy spectrum of electrons in doped, intentionally disordered superlattices is calculated with allowance for the Coulomb fields generated by the redistribution of electrons among the quantum wells. An approach based on density functional theory is used in conjunction with a numerical technique to investigate the influence of screening on the vertical disorder, in particular, on the distribution of quantum-well levels in such structures. It is shown that screening shifts the maximum of the distribution and significantly decreases its width; this effect can result in delocalization of the electronic states governing the vertical conductivity of the structure.