Trions in GaAs Quantum Wells: Photoluminescence Lineshape Analysis

Physical Review B, 2000

Electron-trion photoluminescence spectra were measured in undoped high-quality GaAs quantum wells. The obtained line shape depends on temperature and is asymmetric with a tail towards lower photon energies. For a detailed understanding, we have solved numerically the trion Schrödinger equation in the quantum well. Both electron and hole trions are considered. Good agreement is found for the trion binding energy and for the luminescence line shape at different temperatures. The radiative lifetime of thermalized trions is found to increase linearly with temperature. Analytical results are given for both types of trions taking into account the finite photon wave vector ͑light-cone effect͒.

Physica E: Low-dimensional Systems and Nanostructures, 2011

Emission maxima related to the recombination of excitons (e1-hh1, e1-lh1, e2-hh2, and e2-lh2) were observed in photoluminescence spectra of GaAs/In 0.3 Ga 0.7 As/GaAs quantum wells. The emission bands due to e1-hh1 and e1-lh1 transitions were found to have a doublet character explained by the exchange interaction of excitons in quantum wells. Emission bands due to radiative E b -hh1, E b -lh1 transitions in the buffer GaAs layer are observed in the region of 1.5 eV.

Europhysics Letters (EPL), 1990

We report on continuous-wave and time-resolved measurements of the photoluminescence of goodquality single quantum wells at low temperatures (4-30 K). Luminescence arising from both free and localized excitons is observed and the inhuence of excitation localization on the photoluminescence decay time is investigated. Resonant pumping at the light-hole exciton transition is found to greatly increase the generation of free heavy-hole excitons. In this case, the free-exciton lifetime increases linearly with temperature (10-30 K) and the dependence of the slope on the well thickness is found to be in good quantitative agreement with the theoretical model of Andreani et al. [Solid State Commun. 77, 641 (1991)].

Journal of Applied Physics, 2000

We obtain the temperature dependence of the homogeneous linewidth of excitons in GaAs quantum wells ͑QWs͒ and bulk GaAs using photoluminescence measurements. The results indicate that exciton scattering rates with optical phonons are larger in bulk GaAs than in QWs.

Solid State Communications, 1996

Measurements of the picosecond time-resolved intensity-correlated nonlinear photoluminescence (NLPL) spectra are made at different excitation densities in the range 4 x lo9 to 2 x lO"~rn-~ on high quality GaAs Quantum Wells (QWs) at 8K. We consider various possible models to understand the observed NLPL spectral shapes, which show a sharp prominent negative peak at the exciton energy with a positive sidewing on either side. We suggest that the most likely origin of the observed lineshape is collision broadening of the luminescence due to delocalized excitons. The presence of additional nonlinear effects, such as the density dependent exciton radiative lifetime and fermion exclusion, can also be deduced from the analysis.

physica status solidi (b), 2012

The effects of intense laser radiation on the exciton states in GaAs-Ga 1-x Al x As quantum wells are studied with the inclusion of applied dc electric fields oriented along the growth direction of the system. The calculations are made within the effective mass and parabolic band approximations. The intense laser effects have been included along the lines of the Floquet method, modifying the confinement potential associated to the heterostructure. The results for the exciton binding energy, the energy of the exciton-related photoluminescence peak, and the carriers overlap integral are presented for several configurations of the quantum well size, the strength of the applied electric fields, and the incident laser radiation.

Physical Review B, 2005

Measurements of the THz absorption and the time-resolved photoluminescence have been performed on the same GaAs quantum well sample. The strength of the absorption at the internal 1s-2p exciton transition frequency is used as a measure of the density of excitons in the sample. When the interband pump laser is resonant with the 1s exciton frequency, induced absorption at the 1s-2p frequency is clearly seen. If the same density of carriers is created pumping in the continuum, no significant 1s-2p absorption is seen in a time window of 450 ps. Complementary time-resolved photoluminescence experiments, detecting the emission at the exciton energy under the same pump conditions, show the PL intensity in resonant and nonresonant cases to be similar. The counter-intuitive existence of luminescence at the exciton energy simultaneously with the absence of the 1s-2p absorption is consistent with the recent theoretical predictions of Kira et al., Phys. Rev.

2003

The in-plane motion of negatively charged excitons (X Ϫ) in modulation-doped GaAs quantum wells ͑QW's͒ was studied by means of spatially resolved photoluminescence spectroscopy. In the highest-quality QW's, resonantly excited X Ϫ were observed diffusing from the excitation region, characterized by a mobility as high as 6.5ϫ10 4 cm 2 V Ϫ1 s Ϫ1 , independent of temperature and electron density. Under the application of an electric field in the plane of the QW, X Ϫ were found to drift in the direction opposite to the field, whereas neutral excitons ͑X͒ do not drift under similar conditions. The results demonstrate that X Ϫ can exist as a free quasiparticle in the best-quality samples. The simultaneous motion of nonresonantly excited X and X Ϫ was studied as a function of the electron density in the QW. The data reveal that the spatial distribution of X and X Ϫ is mainly determined by the motion of X that locally form X Ϫ .

Japanese Journal of Applied Physics, 2013

Dynamics of excitons in GaInNAs/GaAs quantum wells (QWs) is studied theoretically within a model of hopping excitons. In this model the temporal evolution of photoluminescence (PL) is described by the system of rate equations which takes into account hopping of excitons between randomly generated localizing states. In this work we study the influence of temperature on such characteristic features of PL as the decay and rise time of PL signal as well as their spectral dependences. It is clearly shown that our model reproduces experimental data very well.

Physical Review B, 1988

The photoluminescence spectra from a number of high-quality GaAs single-quantum-well samples grown by molecular-beam epitaxy reveal a doublet emission having an energy separation of-1.25 meV. A similar doublet was observed in a sample for which the interrupted growth technique was used. Using excitation-intensity-dependent luminescence and time-resolved spectroscopy,~e will show that the lower-energy components of these doublets have diN'erent origins in di6'erent samples and can be attributed either to biexcitons or to impurity-bound excitons. Using low-temperature photoluminescence (PL) from a number of high-quality GaAs multiple-quantum-well samples grown by molecular-beam epitaxy (MBE), Miller and co-workers'2 first reported a double peak whose splitting was-1 meV. The high-energy peak was attributed to the n 1 heavy-hole-free-exciton transition. Based on the excitation intensity, temperature, and polarization dependencies of the lower-energy peak, they concluded that this transition was due to biexcitons with a binding