EXCITONS CONFINED BY SPLIT-GATE POTENTIALS

Quasi-one-dimensional excitons in a GaAs-AlxGa1-xAs quantum well are s tudied; they are produced by an applied twin-split-gate potential whic h confines the particles laterally and allows free motion in one dimen sion. A variational approach is used to calculate the binding energies E(ex) and oscillator strength f(ex) of these excitonic transitions as functions of the applied voltage and width of the induced potential w ells. In the limit of high electrostatic confinement the excitons are strongly polarized and the system resembles a type II structure where electron and hole are spatially separated. The resulting E(ex) and f(e x) show a strong dependence on applied voltage and structure width. St rong oscillations are found, which should be observed experimentally, as a consequence of subtle competition between confinement and Coulomb attraction.