EXCITONS IN V-SHAPED AND T-SHAPED SEMICONDUCTOR QUANTUM-WELL WIRES

We give a general framework for describing electronic states in isolat ed quantum wires. It provides a description of both the conduction ban d and the valence band, taking full account of the complexity of the G amma(8) valence band. This is applied to T-shaped wires and V-shaped w ires. To make a useful comparison with experimental results we calcula te the exciton Rydberg. We show that in the case of the T-shaped wires hole confinement is due to the interaction with the confined electron and not due to the confining potential: the red shift of the wire exc iton line with respect to that of the quantum well is mainly due to th e decrease of the electron confinement energy and only partially to th e increase of the exciton Rydberg. The experimental results are reprod uced with no adjustable parameters.