Enhanced confinement energy in strained asymmetric T-shaped quantum wires

A new type of T-shaped quantum wire, based on a sri strained asymmetric structure, has been grown and characterised. A narrow GaAs well is overgrown on an multi quantum well structure consisting of wide InAlGaAs c ells with Al0.3Ga0.7As barriers. Since the lattice constants of the InAlGaAs wells and bulk GaAs are different, the overgrown well is strained at the T-shaped intersection. The influence of the strain on the confinement energy is investigated by comparison with similar unstrained asymmetric structures and calculated values. A strain-induced enhancement of the confinement energy of 5-10 meV is found for In molefractions of 10% and 15%, in the multi quantum wells. For an In mole fraction of 20% no quantum wire states are observed, probably due to dislocation formation in the overgrown layers.