We investigate the origin of radiative recombination in (InGa)(AsN)/GaAs single quantum wells by means of continuous wave and time-resolved photoluminescence (PL) measurements. Samples with different indium and nitrogen concentration were investigated. An analysis of the whole set of data for different excitation densities and lattice temperatures, T, is reported. This analysis provides insights into radiative and non-radiative processes ruling the recombination dynamics and shows the predominant contribution of localized state emission at low T. The nature of these states is further studied by measuring the time necessary (rise time) for their population. We find that the PL rise time in (InGa)(AsN) is independent of temperature and detection energy, thus being not conclusive about the origin of the states involved in the emission processes. On the contrary, magneto-PL measurements show that the shift of the PL peak energy induced by a magnetic field, B, decreases sizably and changes its dependence on B from linear to quadratic when going from low to high temperature. This counterintuitive result shows that radiative recombination at low temperature (T<100 K) is not excitonic, contrary to previous assignments, and is due to loosely bound electron-hole pairs in which one carrier is localized by N-induced potential fluctuations and the other carrier is delocalized.
In this work, the experimental evidence of exciton confinement in the GaAs barriers of InGaAs/GaAs multiple-quantum-well structures is reported. This has been achieved by an ad hoc devised luminescence self-absorption spectroscopy method, as well as by standard photoluminescence, performed at different temperatures, which present a spectral feature at energies higher than those of bulk GaAs. The confinement energy and the linewidth depend on the barrier width, in agreement with a simple quantum mechanical model. Higher index states of the barrier exciton are also observed. The data underscore the critical importance of the choice of the sample-structure parameters for the confinement to be detectable.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.