Influence of spin-orbit split-off band on optical properties of spherical semiconductor nanocrystals. The case of CdTe.

The multiband envelope-function formalism, including the effects of finite spin-orbit splitting energy Delta, is used to calculate valence-band confined states in spherical semiconductor nanocrystallites. A compact analytical formulation of the necessary equations is proposed. In the particular case of CdTe, despite the large value of Delta, the split-off band has a sizeable influence on the fundamental interband transition, which is found dipole-forbidden, by symmetry. This result cannot be accounted for by usual models in which the influence of the split-off band is a priori neglected, when Delta is large. The consequences of basic assumptions on this prediction, which should have important consequences on intrinsic luminescence, are discussed.