Optical Anisotropy in a Quantum-Well-Wire Array with Two-Dimensional Quantum Confinement

A photoluminescence study of an (AlGa)As-GaAs quantum-well-wire array directly grown by molecular-beam epitaxy on a tilted substrate is described. A strong anisotropy was observed in the ratio of the electron-light-hole-exciton peak intensity to the electron-heavy-hole-exciton peak intensity. A theory incorporating the optical selection rule for two-dimensional quantum confinement is found to agree very well with the measured data. These results constitute the first evidence of two-dimensional quantum confinement in artificial wire structures having cross-sectional dimensions in the nanometer range.