Transfer mechanisms and geometry effect on the dynamics of excitons in boron-containing GaAs alloys: Time-resolved photoluminescence investigation

The recombination dynamics in BxGa1-xAs alloys on GaAs (001) grown by metal-organic chemical vapor (MOCVD) are investigated using steady-state photoluminescence and Time-Resolved Photoluminescence (TRPL) measurements in the nanosecond range. The decay time as a function of the emission energy and the geometry of the sample (quantum well, epilayer) and post-growth treatment (annealing) is slower for lower-energy emission. In correlation with a systematic study on the photoluminescence features, we have studied the temperature effect on the decay time of the photogenerated carrier. Depending on the geometry of the sample, the exciton dynamics is assisted by the localization phenomenon in the boron-based ternary alloys. It is shown that, at low temperatures, the transfer is mainly ensured by tunneling through localized states where the recombination process is found to be purely radiative in nature. At intermediate temperatures, a competitive process between radiative and non-radiative recombination takes place. For high temperatures, the transfer is assisted by thermal activation, leading to purely non-radiative recombination. We have shown that the unknown state-of-the-art kinetic parameters of thee stage of carrier relaxation and additional carrier recombination dynamics, divulges the particular role of bandgap inhomogeneity and the below-band gap states for the relaxation dynamics that can contribute to the photogeneration mechanisms in BxGa1-xAs/GaAs alloys. Indeed the research findings of this article will help to gain insight into the preliminary carrier relaxation dynamics in boron-based materials.

Automated summary

The recombination dynamics of BxGa1-xAs alloys grown on GaAs (001) by metal-organic chemical vapor deposition (MOCVD) were investigated through steady-state photoluminescence and Time-Resolved Photoluminescence (TRPL) measurements. The decay time was found to vary depending on emission energy, sample geometry, and post-growth treatment. Exciton dynamics in boron-based ternary alloys were influenced by temperature, with different mechanisms dominating at low, intermediate, and high temperatures. The research findings highlighted the importance of bandgap inhomogeneity and below-band gap states for carrier relaxation dynamics in BxGa1-xAs/GaAs alloys.