Absorption and photoluminescence studies of the temperature dependence of exciton life time in lattice-matched and strained quantum well systems

Abstract

We present systematic studies of the temperature dependence of linewidths and lifetimes of excitonic transitions in quantum wells grown by molecular beam epitaxy using both photoluminescence and optical absorption. The temperature ranged from GI< to room temperature. Samples under investigation were lattices matched Ga.ils/AlGaAs and InGaAs/InAlA s, and strained InGaAs/GaAs and ln-GaPls/AlGaAs quantum well systems.

Thermal expansion contribution to the temperature dependence of excitonic transitions in GaAs and AlGaAs

“…The PL peak energy at 1.869 eV with 28.2 meV of FWHM, is associated with the recombination due to impurity states. The recombination involving the impurities has its intensity reduced by the increase in the temperature, disappearing at temperatures above 120 K. This is a classical behavior of impurity and has been observed by many research groups [36][37][38]. Additionally, the impurity nature of the lower energy PL peak was verified by analyzing its behavior as a function of the excitation intensity (not shown in this paper).…”

“…Additionally, the impurity nature of the lower energy PL peak was verified by analyzing its behavior as a function of the excitation intensity (not shown in this paper). It is known that in MBE grown films carbon impurities incorporate into the lattice and produce an acceptor state approximately 20 meV below the GaAs gap [36][37][38]. In our samples, the acceptor impurities are identified by its position in energy as being carbon (e, A o ).…”

Exciton-phonon scattering in GaAs/AlAs quantum wires

“…10 ͑Here, ⌫ G and ⌫ L are full widths at half maximum of the Gaussian and the Lorentzian, respectively.͒ It is expected that the line shape is predominantly determined by inhomogeneous broadening at low temperatures where exciton-phonon scattering becomes relatively ineffective. We note that the line broadening in general has an inhomogeneous as well as a homogeneous part.…”

Role of Localized States in Photoluminescence Dynamics of High Optical Gain CsPbBr3 Nanocrystals

“…Recent studies show ultralow threshold density (≈4.5 µJ cm −2 ) for amplified spontaneous emission (ASE) in CsPbBr 3 nanocrystals (NCs) film. [18] Some recent studies [19,20] of the fine structure analysis of the excitonic and PL spectra of CsPbX 3 (X = Cl, Br, I) NCs show the presence of trion formation at low T. These trions are red-shifted by few meV from free excitons peak and decay radiatively with much faster rate than the excitons which results in faster PL decay at low T. [19,21] It has also been argued that the lowest triplet excitonic states are bright (emission red-shifted by few meV) in this material which is the cause of the higher photon emission rate. Some recent studies have been devoted to investigating excitonic recombination processes in this material at ultrafast timescale.…”