EXCITONS CONFINED BY SPLIT-GATE POTENTIALS

Quasi-one-dimensional excitons in a GaAs-AlxGa1-xAs quantum well are studied; they are produced by an applied twin-split-gate potential which confines the particles laterally and allows free motion in one dimension. 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 wells. 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(ex) show a strong dependence on applied voltage and structure width. Strong oscillations are found, which should be observed experimentally, as a consequence of subtle competition between confinement and Coulomb attraction.