GaAs/AlGaAs quantum wires fabricated by SiO₂ capping-induced intermixing

We demonstrate that selective intermixing of GaAs/AlGaAs quantum well heterostructures induced by SiO₂ capping and subsequent annealing can be spatially localized on a length scale compatible with the lateral confinement of carriers into quantum wires. Low temperature optical spectroscopy measurements including linear polarization anisotropy analysis show evidence of the formation of one-dimensional subbands. A mechanism involving the ability of the thermal stress field generated in the heterostructure by the patterned SiO₂ film to pilot the diffusion of the excess Ga vacancies, which are responsible for the enhanced interdiffusion under SiO₂ is suggested to account for the high lateral selectivity achievable with this novel process.