Electronic structure of CdTe nanocrystals:: a tight-binding study

We present a symmetry-based calculation of the electronic structure of a compound semiconductor quantum dot (QD) in the sp(3)s* tight-binding model including the spin-orbit interaction. The Hamiltonian matrix is diagonalized exactly for CdTe QD sizes up to 60 Angstrom. The surface dangling bonds are passivated by hydrogen through a careful analysis of the density of states and wave functions. The calculated size dependence of the energy gap shows a reasonable agreement with the available experimental data. Our symmetry analysis indicates that, in contrast with a reported prediction of the three-band effective-mass model, the fundamental interband transition remains dipole-allowed in CdTe nanocrystals. (C) 1999 Elsevier Science Ltd. AU rights reserved.