THE EFFECTS OF CRYSTALLOGRAPHY AND LATERAL INTERMIXING ON THE SUBBAND STRUCTURE AND OPTICAL ANISOTROPY IN QUANTUM-WIRE ARRAYS ON VICINAL SUBSTRATES IN THE LAYER-ORBITAL MODEL

Materials-characterization studies indicate a high degree of lateral intermixing in quantum-wire arrays grown on vicinal substrates. In this study, the layer-orbital model, which is a variation of the effective bond-orbital model, is used to calculate the zone-center conduction- and valence-subband energies and optical matrix elements of recently grown epitaxially buried GaAs/AlGaAs/AlAs quantum wires and quantum-wire arrays. The lateral intermixing effect is included using a compositional profile that has the merit that it is appropriate for the entire range of lateral intermixing, whether small or large, and that is computationally efficient. The effect of the orientation of the quantum wires on the subbands and the optical matrix elements is also investigated. For uncoupled quantum wires, the orientation mainly affects the positions of the valence subbands; the optical matrix elements are nearly independent of the orientation. The situation for the quantum-wire array is more complicated due to its intermediate nature between one and two dimensional. It is found that only the position of the light-hole subband is appreciably affected. It is also found that quantum-wire arrays misoriented from the [011] ([011BAR]) direction display somewhat reduced optical anisotropy.