<title>Bipolar charge transport in triple-barrier AlAs/GaAs resonant tunneling light-emitting diodes</title>

The quantum-well emission originating from triple-barrier AlAs/GaAs resonant tunneling light emitting diodes has been investigated. In these devices, three barriers defined two asymmetric quantum wells. Two nominally identical structures were grown that had a different sequence of the two quantum wells. Depending on which well was the first well for the electron tunneling transport, double or triple resonances were observed. In the latter case, the two- dimensional accumulation layer is aligned with the subbands from both wells. The subband occupation and the charge distribution between the two wells is studied, showing that at any resonance the wider of the two wells will emit more luminescence but at a double resonance the narrower well can be the stronger light emitter. Bandstructure calculations under all bias conditions further confirm the occurrence of both kinds of resonances in these triple-barrier structures.