Anomalous photoluminescence behavior in GaAs/AlAs superlattice-like double-barrier diodes under bias

Abstract

Transport and optical properties of a GaAs/AlAs superlattice-like double-barrier diode were studied by continuous-wave photoluminescence spectroscopy. An enhancement of the quantum-well photoluminescence intensity with increasing temperatures is reported in biased diodes, which is related to transport properties, disappearing at zero-applied voltage. The anomalous observed behavior can be explained in terms of the temperature-dependent transport properties of the minority carriers (holes) in the collector spacer layer, which limits the supply of holes available for tunneling.

Kinetics of excitonic complexes on tunneling devices

“…Measurements were performed by varying the excitation intensity between 1 and 10 W / cm 2 and the temperature in the range 8 -50 K. To confirm the nature of the lowerenergy line associated with X − recombination, additional measurements ͑not shown in this work͒ were performed at several temperatures, laser excitation, and magnetic fields up to 15 T, using an Oxford superconducting magnet. 18 No signal was observed in PL experiments at zero bias, indicating that the holes photogenerated in the contact can only reach the well layer by tunneling through heavy-hole and lighthole levels of the QW.…”

“…18,19 Besides, the formation of biexcitons would also require large populations of holes. However, below the onset of current ͑low voltage͒, excitons show stronger emission than trions and, as mentioned above, the neutral exciton density is higher than the trion density and the X − / X 0 intensity ratio is smaller than 1 ͓see Fig.…”

“…The validity of this relationship in GaAs/ Al x Ga 1−x As double barrier diodes and its connection with the measured current was also investigated. 18 Buhmann et al 19 described the appearance of an additional emission line on the low-energy side of the PL spectra of double barrier diodes due to trion recombination. This emission increases as charge is accumulated in the QW that enhances the formation of trions.…”

Thermal equilibrium governing the formation of negatively charged excitons in resonant tunneling diodes

“…These photogenerated holes drift and diffuse to the collector barrier, tunnel into the well, and recombine with the electrons in the well. 16,17 The accumulation of charge in the QW is controlled by the bias, so high electron densities are expected close to the resonance. The quantum-well PL emission for voltages in the range 0.22-0.52 V are all very similar to the 0.42 V spectrum presented in Fig.…”