QUANTUM WIRES WITH STRAIN EFFECT - TIGHT-BINDING ANALYSIS

We discuss a tight-binding calculation of the band structure of InGaAs/InAlGaAs strained quantum wires, which exhibits properties distinct from both quantum wells and unstrained quantum wires. In and InGaAs wire simply embedded in GaAs, however, the InGaAs band gap can become larger than that of the GaAs, which is due to tri-directional hydrostatic pressure. Depending on the band offsets, this can imply a type-II band alignment. Therefore, to investigate how the strain effects modify the band structure of the quantum wires, we discuss a biaxially strained structure in which the InGaAs wire region is embedded in a plane of InAlGaAs with the same lattice constant, between two-dimensional barrier layers of AlGaAs. We find that the effect of the valence band mixing is reduced, thus decreasing the nonparabolicity of the valence bands. Moreover, the symmetry between the conduction and valence band densities of states is enhanced.