TIME-DEPENDENCE OF QUANTUM-WELL RECOMBINATION LUMINESCENCE IN A BIPOLAR ALAS GAAS RESONANT-TUNNELING STRUCTURE/

The tunnelling transport of electrons and holes is investigated in a d ouble-barrier AlAs/GaAs resonant tunnelling light-emitting diode (RTLE D) biased below flat band (approximate to 1.5 V) using time-resolved p hotoluminescence (PL) spectroscopy. For photon energies above the conf ined exciton transition, a fast decaying PL component is observed whic h is ascribed to electron escape after e-h pair creation inside the we ll, with a characteristic time of 1 ns close to flat band and decreasi ng with electric held in the well. Below 1.1 V,photocarriers generated outside the well give rise to a slow decay component with characteris tic times up to 3 ns, which is attributed to slow nonresonant tunnelli ng of electrons and holes from the respective depletion layers into th e well. At lower external bias (higher field) the overall decay become s faster due to faster hole tunnelling, as indicated by a qualitative change of the time dependence of the PL signal, and the relative growt h of the light-hole exciton FL. (C) 1998 Elsevier Science B.V. All rig hts reserved.