Radiative and non-radiative recombination of thermally activated magneto-excitons probed via quasi-simultaneous photoluminescence and surface-photovoltage spectroscopy

Abstract

The effect of the magnetic field on radiative and non-radiative mechanisms of charge carriers in GaAs/AlGaAs quantum wells (QWs) is investigated via quasi-simultaneous magneto-photoluminescence (PL) and magneto-surface photo-voltage (SPV) spectroscopy. At low-temperature, the luminescence intensity of ultra-low disordered GaAs/AlGaAs QWs generally increases under strong magnetic perturbation. Even at relatively high-temperature (100 K), the magnetic field driven enhancement of PL intensity is observed for thick QWs. On the other hand, it is found that the PL intensity of narrow QWs gradually decreases under a strong magnetic field at 100 K. The magnetic field driven enhancement (suppression) of radiative recombination efficiency for wide (narrow) QWs is investigated by considering the oscillator strength, thermal effects, and carrier re-distribution in energy states. Also, the charge carriers which escape from narrow QWs or are captured by interface defects are probed via magneto-SPV measurements. Radiative recombination and thermionic emission of charge carriers, investigated by magneto-PL and magneto-SPV spectroscopy, provide a clear guideline of the critical QW width which would be essential for magnetic field driven high-temperature operation of advanced emission based-devices.

Influence of interface states on built-in electric field and diamagnetic-Landau energy shifts in asymmetric modulation-doped InGaAs/GaAs QWs

“…The blue shift of the P 0 peak as a function of the magnetic field (depicted by the dotted green line in S2 and S3, figures 9(b) and (c)) indicates the additional energy supplied by an applied magnetic field to assist this de-trapping process. Another important factor could be the magnetic field-driven decrease in excitonic recombination lifetime (τ r ) related to the QW ground state [56]. Therefore, the QW charge carriers become more prone to recombine via QW states rather than their capture into the (interface) defect states at a high magnetic field.…”

Photovoltaic Response and Charge Redistribution Processes in GaAs/AlGaAs Multiple‐Quantum Wells Structure

“…This is because most of the photo‐excited electrons in this low‐temperature regime radiatively recombine with holes, which leads to a strong luminescence signal. [ 47 ] In addition, a significant number of electrons are captured by point defects in QWs, which is shown by magenta arrows in Figure 3 . As a result, the probability of carrier redistribution within QWs or the thermal escape of electrons becomes feeble, which causes a negligibly small SPV signal in region‐I.…”