Tunnelling dynamics of holes in GaAs/Al0.33Ga0.67As double-barrier resonant tunnelling structures studied by time-resolved photoluminescence spectroscopy

Abstract

The authors have studied a biased double-barrier resonant tunnelling structure using time-resolved and continuous-wave photoluminescence (PL) spectroscopy and identified the principal mechanisms which contribute to the evolution of luminescence from the quantum well (QW) region. They find that in the structures investigated the PL intensity is dominated by the diffusion and tunnelling of minority holes, in contrast with several earlier studies in which the electron behaviour was suggested to control the PL characteristics. The processes dominating the variation of PL intensity with bias are: field-driven accumulation of holes in a layer adjacent to one barrier, tunnelling of holes from this layer into the QW and the escape of holes from the QW by tunnelling at low bias, and at high bias by direct escape over the emitter barrier. Additionally, the absence of luminescence corresponding to recombination from the upper electron level when the device is biased at the second tunnelling resonance implies fast inter-subband scattering for charge carriers in the QW.