Resonantly Excited Time-Resolved Photoluminescence Study of Self-Organized InGaAs/GaAs Quantum Dots

Heitz, R.; Born, H.; Lüttgert, T.; Bimberg, D.

doi:10.1002/1521-3951(200009)221:1<65::aid-pssb65>3.3.co;2-q

Cited by 4 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Note that the rise time corresponds to the decay time observed for the resonant PL of I1 ͑not shown, equivalent results for similar samples have been reported recently͒. 23 Obviously, the relaxation of the excited I1 state is the bottleneck in the excitation of the ground state I0, i.e., the rise time is determined by the balance of relaxation and recombination of the I1 state. The observation of multi-LO-phonon resonances in the PLE efficiency for InAs/GaAs QD's reported recently 6,8 -10 indicates direct relaxation of I1 to I0 in a single-step process, demonstrating that a simplified quasi-particle ͑exciton͒ term scheme as shown as inset in Fig.…”

supporting

confidence: 70%

Existence of a phonon bottleneck for excitons in quantum dots

et al. 2001

Self Cite

View full text Add to dashboard Cite

A phonon bottleneck is manifested for correlated electron/hole ͑exciton͒ states in self-organized In x Ga 1Ϫx As/GaAs quantum dots ͑QD's͒ with a flat, truncated shape. Suppressed relaxation and hot luminescence from excited states in the low-density regime are demonstrated. The long low-temperature relaxation time of ϳ7.7 ns, being ϳ15 times the radiative lifetime, is attributed to a quenched polar exciton-LO-phonon coupling in truncated QD's based on eight-band k•p model calculations.

show abstract

supporting

confidence: 70%

Existence of a phonon bottleneck for excitons in quantum dots

et al. 2001

Self Cite

View full text Add to dashboard Cite

show abstract

“…Without detailed knowledge of the QD DOS it is unclear which model will correctly predict our escape time and justification for both methods can be found in the literature. Temperature dependent DT measurements with nonresonant pumping, 18 timeresolved PL, 19 and photoluminescence excitation (PLE) 20 experiments reveal that carrier capture proceeds by multiphonon emission at low carrier densities, lending credence to the multiphonon approach. On the other hand, a thermal model correctly predicts the time-resolved and timeintergrated PL from some QD samples.…”

Section: Temperature Dependent Measurementsmentioning

confidence: 99%

Lateral coupling of InxGa1−xAs∕GaAs quantum dots investigated using differential transmission spectroscopy

2004

View full text Add to dashboard Cite

Coupling between InGaAs/ GaAs quantum dots is investigated using differential transmission spectroscopy. Two-color pump-probe techniques are used to spectrally resolve the carrier dynamics, revealing carrier transfer between quantum dots at room temperature. The time constant for this process is shown to increase from 35 ps at room temperature to 130 ps at 230 K.Self-assembled semiconductor quantum dots (QDs) are remarkably flexible structures that are impacting many areas of optoelectronics. At low temperatures, they exhibit atomiclike properties due to their three-dimensional electronic confinement and are promising for such applications as quantum computing and cryptography. Self-assembled QDs have also proven useful when incorporated into conventional devices such as semiconductor lasers and amplifiers. Unfortunately, many of the major device improvements anticipated due to the unique QD density of states have not been realized. This is due in part to the as yet unavoidable size distribution in QD ensembles, but also due to the significant temperature-dependent coupling of individual QD transitions. Temperature-dependent coupling affects the threshold current density in QD lasers 1 and limits the isolation between channels in a QD semiconductor optical amplifier and other multichannel devices. 2,3 Coupling between QDs in optoelectronic devices occurs via both electromagnetic and electronic mechanisms. The former couples all QDs within a homogeneous linewidth of the individual transition. The latter can couple all QDs within the inhomogeneous linewidth as electrons and holes move between QDs with different ground state energies. Each of these effects can result in Fermi level pinning and, therefore, explain the observed single-mode operation of QD lasers at room temperature. 4 In actuality, both of these processes contribute to the collective action of QD ensembles and can be difficult to distinguish. Recently, coupling in self-assembled QD ensembles has been studied extensively. The room temperature homogeneous broadening of the transition has been measured by four wave mixing 5 and single QD emission 6,7 with values ranging from a few nanometers up to more than 10 nanometers. Electronic coupling of QDs via thermal emission and subsequent recapture has been inferred from temperature dependent continuous-wave 8,9 and time-resolved 10,11 photoluminesence (PL) measurements. Unfortunately, this method relies on numerous assumptions and a multivariable fit to a series of data. Results from resonant differential transmission (DT) measurements 12,13 show an initial fast recovery of the QD absorption indicating that carriers are quickly leaving the states that they were initially created in. These experiments cannot determine whether the resonantly excited carriers are moving to other QDs or different states of the same QD.This paper is orginized as follows. Section I contains information on the growth and preparation of the sample as well as the experimental methods employed for this study. Section II contains room ...

show abstract

“…3,4 The intradot carrier dynamics is determined by a nontrivial interplay between carrier-carrier and carrier-phonon scattering. Experiments 5 have shown that electron-phonon scattering is very sensitive to the geometry of the dots, which tailors the electron and hole wave functions and thus the electron-phonon interaction strength. In lens-or disk-shaped QD's with high electronic symmetry, quenching of the electron-LO-phonon interaction is responsible for an effective phonon bottleneck at low temperatures.…”

mentioning

confidence: 99%

Coulomb and carrier-activation dynamics of resonantly excited InAs/GaAs quantum dots in two-color pump-probe experiments

Quochi¹,

Dinu²,

Pfeiffer³

et al. 2003

Phys. Rev. B

View full text Add to dashboard Cite

We study Coulomb and carrier dynamics in self-assembled InAs/GaAs quantum dots at room temperature by two-color tunable differential transmission experiments, with resonant excitation in the ground state. Coulomb renormalization of the first excited state in the presence of one electron-hole pair in the ground state manifests as a 6-meV redshift. Several time scales for carrier activation to the first excited state are distinguished, corresponding to activation processes occurring in singly and doubly occupied dots, including carrier thermalization. Electron thermal activation occurs on a 250 ps time scale, confirming the absence of a phonon bottleneck at room temperature.

show abstract

Resonantly Excited Time-Resolved Photoluminescence Study of Self-Organized InGaAs/GaAs Quantum Dots

Cited by 4 publications

References 0 publications

Existence of a phonon bottleneck for excitons in quantum dots

Existence of a phonon bottleneck for excitons in quantum dots

Lateral coupling of InxGa1−xAs∕GaAs quantum dots investigated using differential transmission spectroscopy

Coulomb and carrier-activation dynamics of resonantly excited InAs/GaAs quantum dots in two-color pump-probe experiments

Contact Info

Product

Resources

About