Exciton dynamics inInxGa1−

G. Bacher

¹

,

C. Hartmann

²

,

H. Schweizer

³

et al.

Abstract

In a carefully selected set of strained In"Ga& As/CxaAs quantum-well structures, we have studied experimentally and theoretically the competition between carrier collection from the GaAs barrier into the quantum wells and the inverse process, the thermal activated emission out of the wells into the barrier. Analyzing the temperature dependence of time-integrated photoluminescence measurements, we found excitons or electron-hole pairs to be emitted out of the well. A different sample geometry is used to demonstrate the importance of the barrier properties in the equilibrium of capture and thermal emission. Time-resolved experiments allow the determination of the typical time constants, namely the radiative and the nonradiative recombination lifetime as well as the emission time. A hydrodynamic model, including the diffusion in the barrier and the carrier capture and emission via LO phonons, was developed for a quantitative description of our experiments. With use of the experimental time constants, an excellent agreement between the time-integrated experiments and theory was found, giving evidence of the applicability of our model.

InGaAs spin light emitting diodes measured in the Faraday and oblique Hanle geometries

“…This is the polarization after degradation from transit through the device and more importantly, the time spent in the quantum well. Transit through the device will account for a few ps whilst the decay time in the well will be >100 ps [25]. The measured spin lifetime, T s , will have contributions from both the transit through the device and the time in the quantum well.…”

Changes in luminescence emission induced by proton irradiation: InGaAs/GaAs quantum wells and quantum dots

“…In the absence of midgap levels ͑nonradiative recombination͒ the temperature dependence of the integrated PL signal from dense QD ensembles is closely related to their confining potential 21 just as in QWs. 22 Defect induced recombination could lower the values for this activation energy. This could explain the slightly lower activation energy shown in Fig.…”

Magnetic field effects on optical and transport properties inInAs∕GaAsquantum dots

“…Such an increased transport in the WL also increases the capture probability of the carriers into the NRCs, as reflected by the observed decrease of the total integrated luminescence intensity with increasing temperature. At further elevated temperatures, also other nonradiative recombination processes due to thermal activation of carriers from the WL into the barrier material 12,13,16 and nonradiative recombination at the InAs/ GaAs interface 9,17 become significant. As a result, the total integrated PL intensity is further reduced.…”

“…Many studies have shown that increased temperatures ͑up to a certain temperature͒ will cause an increase of the radiative recombination time in twodimensional quantum structures. [9][10][11][12] Feldmann et al 10 explained the temperature dependence of the decay time in terms of momentum conservation for the free excitons. Since a thermal broadening of the free exciton will reduce the k = 0 exciton population, a smaller fraction of the excitons will fulfill the momentum conservation criteria and an increased exciton lifetime is expected.…”