Purely strain induced GaAs/InAlAs single quantum wires exhibiting strong charge carrier confinement

Atomically precise strained quantum wire structures are obtained using the cleaved edge overgrowth technique. Strong carrier confinement is achieved purely by lateral strain variation within a single quantum well. In the first growth direction InAlAs layers serve as stressor material. Growing a GaAs quantum well directly on the cleaved (011) plane in a second growth step, one ends up with a strongly strain modulated T-shaped structure. The confinement energy rises as expected with the thickness of the stressor layer and the width of the overgrown quantum well. This is confirmed both by numerical simulations and by spatially resolved photoluminescence measurements. Experimentally, confinement energies of up to 51.5 meV with respect to the corresponding energy for the quantum well are obtained, which is approximately twice the value of k_BT at room temperature. The confinement energy can be enlarged by decreasing the incident power, which can be explained by screening effects. The electron and hole wave functions are spatially separated due to the piezoelectric effect which is incorporated in the simulations. The calculations of the strain distributions and wave functions are presented as a tool for optimizing the sample layout.