PHOTOLUMINESCENCE IN GAAS-ALGAAS COUPLED DOUBLE QUANTUM-WELLS IN ELECTRIC AND MAGNETIC-FIELDS

Photoluminescence (PL) spectroscopy has been used to study energy levels in GaAs-AlGaAs coupled quantum well structures. Low temperature investigations were made as a function of (i) applied electric field and (ii) applied magnetic field for asymmetric (ACDQW) and symmetric (SCDQW) coupled double quantum well systems, respectively. The transformation from spatially direct and spatially indirect electron transitions to heavy and light hole states in the wide well of the ACDQW was accomplished by the application of an electric field. Anticrossing behavior associated with both the heavy and light hole excitons were observed. The observed minimum energy splitting of approximately 1.6 meV was in good agreement with the electron tunneling energy obtained from single particle calculation; the results provided more refined values for the barrier width. The magnetic field investigations of a SCDQW, under flat band conditions, showed several allowed magneto-excitonic intersubband transitions. The binding energy and effective mass of the \E0, H0, ls] exciton state in the SCDQW were deduced from the magnetic field data.