VERTICAL TRANSPORT OF PHOTO-EXCITED CARRIERS FOR EXCITONIC RECOMBINATIONS IN MODULATION-DOPED GAAS GA1-XALXAS HETEROJUNCTIONS/

We propose a vertical transport of the photo-excited carriers under th e influence of the two dimensional carrier gas (2DCG) in GaAs/Ga1-xAlx As heterojunctions before excitonic recombination. The vertical transp ort is responsible for a long photoluminescence (PL) rise time of the excitonic transitions as well as for the PL intensity oscillations wit h magnetic field. The vertical transport is proved for the first time by resonant PL intensity variation at the cyclotron resonance conditio n of the 2DCG, by which the effective masses of two dimensional electr ons as well as two dimensional holes in the n- and p-type heterojuncti ons are determined. (C) 1998 Elsevier Science Ltd. All rights reserved .