TUNNELING DYNAMICS OF HOLES IN GAAS AL0.33GA0.67AS DOUBLE-BARRIER RESONANT-TUNNELING STRUCTURES STUDIED BY TIME-RESOLVED PHOTOLUMINESCENCE SPECTROSCOPY/

We have studied a biased double-barrier resonant tunnelling structure using resolved and continuous-wave photoluminescence (PL) spectroscopy and identified the principal mechanisms which contribute to the evolu tion of luminescence from the quantum well (QW) region. We find that i n the structures investigated the PL intensity is dominated by the dif fusion and tunnelling of minority holes, in contrast with several earl ier studies in which the electron behaviour was suggested to control t he PL characteristics. The processes dominating the variation Of PL in tensity with bias are: field-driven accumulation of holes in a layer a djacent to one barrier, tunnelling of holes from this layer into the Q w and the escape of holes from the QW by tunnelling at low bias, and a t high bias by direct escape over the emitter barrier. Additionally, t he absence of luminescence corresponding to recombination from the upp er electron level when the device is biased at the second tunnelling r esonance implies fast inter-subband scattering for charge carriers in the QW.