Carrier escape dynamics in a single quantum well waveguide modulator

Bambha, Ray P.; Hutchings, D. C.; Snelling, M. J.; LiKamWa, Patrick; Miller, A.; Moretti, A. L.; Wickman, Randy W.; Stair, K. A.; Bird, T.; Cavaillès, Jean; Miller, D. A. B.

doi:10.1007/bf00430338

Cited by 7 publications

(9 citation statements)

References 16 publications

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“…In most applications, this time constant determines the maximum operational frequency of the device. As was established by previous experimental and theoretical work [6] and confirmed by our calculations [7], the main escape mechanism from an SA at room temperature has a thermal-activation nature. The SA recovery time increases exponentially with the depth of the QW.…”

supporting

confidence: 87%

Quantum-Well Design for Monolithic Optical Devices With Gain and Saturable Absorber Sections

Nikolaev

Avrutin

2004

IEEE Photon. Technol. Lett.

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supporting

confidence: 87%

Quantum-Well Design for Monolithic Optical Devices With Gain and Saturable Absorber Sections

Nikolaev

Avrutin

2004

IEEE Photon. Technol. Lett.

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“…It is important to note that, if the in-plane mass is taken to be energy-independent (i.e., the same for all bound and unbound states), then the escape time for the particular type of particles will not depend on the value of the in-plane effective mass. Indeed, the escape current density (13), as well as carrier density (12), are proportional to the in-plane mass, thus it will cancel when the ratio (18) is taken.…”

Section: B Comparison With Experimental Results For Holesmentioning

confidence: 99%

“…In this paper, we assume that electrons inside the QW are in the state of quasi-equilibrium described by the quasi-Fermi level . In this case, we have (12) where is the electron in-plane effective mass and is the Fermi distribution function, is the inverse temperature measured in energy units, and the spin degeneracy is taken into account by the factor of two.…”

Section: A Escape Currentmentioning

confidence: 99%

“…This expression is valid if is small, i.e., the flux peak is narrow. Under this condition of the tunneling coefficient being small, the quasi-bound states are well described by a step-like 2-D density of states, and the density of the carriers residing on the quasi-bound level is simply , where is given by (12). By definition, the time of tunneling from a quasi-bound level is given by (16) Here, integration over energy is performed in the vicinity of the quasi-bound level.…”

Section: B Quasi-bound Statesmentioning

confidence: 99%

“…There were attempts to apply the combination of quasi-2-D tunneling and 3-D thermionic emission approaches to describe the total escape time from QW structures [11], [12]. However, it is clear that a QW in an electric field is, strictly speaking, neither a quasi-2-D nor a fully 3-D system.…”

Section: Introductionmentioning

confidence: 99%

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Photocarrier escape time in quantum-well light-absorbing devices: effects of electric field and well parameters

Nikolaev

Avrutin

2003

IEEE J. Quantum Electron.

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Article:Nikolaev, V V and Avrutin, E A orcid.org/0000-0001- 5488-3222 (2003) ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract-We analyze the dependence of the carrier escape time from a single-quantum-well optoelectronic device on the aplied electric field and well width and depth. For this purpose, a new simple and computationally efficient theory is developed. This theory is accurate in the case of electrons, and the assessment of the applicability for holes is given. Semi-analytical expressions for the escape times are derived. Calculations are compared to experimental results and previous numerical simulations. Significant correlations between the position of quantum-well energy levels and the value of the escape time are found. The main escape mechanism at room temperature is established to be thermally assisted tunneling/emission through near-barrier-edge states. The formation of a new eigenstate in the near-barrier-edge energy region is found to reduce the electron escape time significantly, which can be used for practical device optimization.Index Terms-Optoelectronic devices, quantum wells (QWs), saturable absorbers.

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Role of Intra‐Band Relaxation of Holes and Tunneling of Electrons in Carrier Relaxation in AlGaAs/GaAs Quantum Well

Khan

Jayabalan

Khamari

et al. 2022

Physica Status Solidi (b)

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Quantum well (QW) structures are being widely used for many applications like lasers, photodiodes, THz emitters, and many next-generation optoelectronic devices leading to the realization of quantum technology. [1][2][3][4][5][6][7][8][9] Optoelectronic applications of such structures lie in harnessing and controlling the carrier relaxation after carriers are excited or injected into these structures. Many relaxation processes like thermalization, intra-band relaxation, inter-valley scattering, defect-state trapping, and radiative recombination have been reported for such QW structures. [10][11][12][13][14][15] Various time-resolved techniques like pump-probe transmission, transient reflectivity measurements, time-resolved photoluminescence, degenerate four-wave mixing, etc. are used to identify the relaxation mechanism and the corresponding time constants. [11,16,17] Such studies give insight into various dynamical processes that occur at different time scales.Loss of carriers from the QW region can happen due to tunneling of carriers and trapping of carriers by the defect states. Understanding of such carrier loss mechanisms in QW is important for their applications in devices. Several groups have performed various time-resolved measurements to address this issue. [15,[18][19][20] However, some of these processes can compete simultaneously with similar time constants which makes their isolation really difficult and complicates the fundamental understanding of carrier dynamics. Further, most of those measurements were carried out by exciting carriers deep into the conduction band and monitoring the radiative emission from the band edge through the time-resolved PL technique (TRPL). TRPL signal covers only the radiative recombination process and indirectly probes the non-radiative loss. Necessary details about the complete nonradiative processes cannot be addressed by TRPL. In contrast, time-resolved pump-probe reflectivity can give information about both radiative and non-radiative relaxation processes. [21][22][23] In this article, timeresolved pump-probe reflectivity measurements at room temperature are performed on AlGaAs/GaAs QW structure to investigate various ultrafast processes that occur over 0.1-10 ps time scale. Using pump-fluence-dependent studies, the origin of various non-radiative relaxation processes in this QW system is probed. By using numerical calculations, it is shown that the carrier loss from the QW region is mainly governed by the tunneling of electrons. Also, several other ultrafast processes occur on a similar time scale. The various relaxation mechanism occurring within the 10 ps time scale are isolated. After isolation of the processes, the timeresolved nonequilibrium dynamics measurements performed in this work have shown the saturation effect in intraband relaxation due to phonon reabsorption.

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Carrier escape dynamics in a single quantum well waveguide modulator

Cited by 7 publications

References 16 publications

Quantum-Well Design for Monolithic Optical Devices With Gain and Saturable Absorber Sections

Quantum-Well Design for Monolithic Optical Devices With Gain and Saturable Absorber Sections

Photocarrier escape time in quantum-well light-absorbing devices: effects of electric field and well parameters

Role of Intra‐Band Relaxation of Holes and Tunneling of Electrons in Carrier Relaxation in AlGaAs/GaAs Quantum Well

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