Size, dimensionality, and constituent stoichiometry dependence of bandgap energies in semiconductor quantum dots and wires

The bandgap energies of semiconductor quantum dots and wires are investigated with respect to the effects of size, dimensionality, and also composition using a nanothermodynamic model. The results indicate: (1) that the bandgap energy increases with decreasing the nanocrystal size for groups IV, III-V, and II-VI semiconductors; (2) that the influence of crystal size on the bandgap energy of quantum wires is weaker than that in the case of quantum dots; (3) that the ratio of Delta E-g(D, d)(QW)/Delta E-g(D, d)(QD) is size-dependent, where Delta E-g(D, d) is the size- and dimensionality-dependent change in bandgap energy; (4) that the category of crystallographic structure (i.e., zinc-blende and wurtzite) appears to have a limited influence on the bandgap energy of semiconductors; and (5) that irrespective of whether or not it occurs in bulk or as nanosized semiconductor alloys, the composition effects on the bandgap energy are substantial, having a common nonlinear (bowing) relationship. These calculated results are consistent with experimental findings and may provide new insights into the influence of size, dimensionality, and composition effects on the bandgap energy of semiconductors.