By means of a tight-binding approach, we have studied the influence of barrier states on the conduction band of the T- and V-shaped quantum wires. For AlAs/GaAs superlattices or pure AlAs barriers, $X$-related states induce strong modifications in the wire conduction band that cannot be accounted for by a simple effective-mass approximation. With respect to quantum wells, we show that the quasi-one-dimensional confinement of quantum wires enhances valley mixing and leads to a reduction in the energy of lower lying states.

• Received 22 April 1997

DOI:https://doi.org/10.1103/PhysRevB.56.R1668