Enhanced confinement energy in strained asymmetric T-shaped quantum wires

A new type of T-shaped quantum wire, based on a sri strained asymmetric str ucture, has been grown and characterised. A narrow GaAs well is overgrown o n an multi quantum well structure consisting of wide InAlGaAs c ells with A l0.3Ga0.7As barriers. Since the lattice constants of the InAlGaAs wells and bulk GaAs are different, the overgrown well is strained at the T-shaped in tersection. The influence of the strain on the confinement energy is invest igated by comparison with similar unstrained asymmetric structures and calc ulated 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 w ells. For an In mole fraction of 20% no quantum wire states are observed, p robably due to dislocation formation in the overgrown layers. (C) 2001 Else vier Science B.V. All rights reserved.