Pseudopotential Theory of Semiconductor Quantum Dots, Wires, and Films

The electronic structure of nanostructures is almost universally addressed by the 'standard model' of effective-mass k.p envelope function approach. While eminently successful for quantum wells, this model breaks down for small structures, in particular, for small dots and wires. Until recently, it was impractical to test the 'standard model' against more general approaches that allow formany-band (gamma-chi-L) coupling. However, it is now possible, due to special tricks, to apply the all-band plane-wave pseudopotential method to 10 to the third-10 to the 4th atom nanostructures.This shows (i) how the 'standard model' fails, in come cases, (ii) how size effect lead to a reduction in dielectric constants and to band gaps that differ from what is expected in effective-mass theory,(iii) the emergence of 'zero-confinement state' in 2D films, (iv) that small dots of III-V materials have an indirect gap that converts to direct above the critical size, (v) how the spectra of CdSe dots evolve from the bulk, and (vi) how the electron-hole Coulomb energy is overestimated by effective-mass wavefunctions.