Magnetopolaron in a weakly elliptical InAs/GaAs quantum dot

Optical transitions in a semiconductor quantum dot are theoretically investigated, with emphasis on the coupling to longitudinal optical phonons, and including excitonic effects. When limiting to a finite number of m electron and n hole levels in the dot, the model can be solved exactly within numerical accuracy. Crucial for this to work is the absence of dispersion of the phonons. A suitable orthogonalization procedure leaves only m(m + 1)/2 + n(n + 1)/2 − 2 phonon modes to be coupled to the electronic system. We calculate the linear optical polarization following a delta pulse excitation, and by a subsequent Fourier transformation the resulting optical absorption. This strict result is compared with a frequently used approximation modeling the absorption as a convolution between spectral functions of electron and hole, which tends to overestimate the effect of the phonon coupling. Numerical results are given for two electron and three hole states in a quantum dot made from the polar material CdSe. Parameter values are chosen such that a quantum dot with a resonant sublevel distance can be compared with a nonresonant one.

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“…These remaining degrees of freedom only contribute to the free phonon energy and are omitted from Eq. (14). A careful inspection of Eq.…”

Section: Reducing the Phonon Subspacementioning

confidence: 99%

“…Thus, we had concluded that this approximation fails if phonons are coupled to discrete electronic levels. Recently, our numerically exact treatment was used to assess results obtained via the Davydov's canonical transformation [14].…”

Section: Introductionmentioning

confidence: 99%

Optical absorption in quantum dots: Coupling to longitudinal optical phonons treated exactly

Stauber

Zimmermann

2006

Phys. Rev. B

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“…The spectrum of a resonant polaron can easily be described for a single-phonon (first order) resonance [5]. However, in most self-assembled structures the energy spacing between the electron levels considerably exceeds the LO phonon energy.…”

Section: Introductionmentioning

confidence: 99%

Second-Order Resonant Polaron in a Self-Assembled Quantum Dot

Kaczmarkiewicz

Machnikowski

2008

Acta Phys. Pol. A

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“…That is, nonradiative processes are about 2300 times faster than radiative processes. Since there are good reasons to believe that the LO-phonon-assisted relaxation time will substantially increase if the relaxing electrons are confined in quantum boxes [7][8][9][10][11][12][13][14][15][16], the radiative efficiency problem can be overcome by replacing the QW active regions of a QC laser with a quantum-box (QB) 2-D array [17] or a 2-D array of cascaded QBs [18]. …”

Section: Introductionmentioning

confidence: 99%

Progress towards intersubband quantum-box lasers for highly efficient continuous wave operation in the mid-infrared

et al. 2009

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Abstract. Intersubband quantum-box (IQB) lasers, which are devices consisting of 2-D arrays of ministacks (i.e., 2-4 stages) intersubband QB emitters have been proposed as alternatives to 30-stage quantum-cascade (QC) devices, for efficient room-temperature (RT) emission in the mid-infrared (4-6 µm) wavelength range. Preliminary results include: 1) the design of devices for operation with 50% wallplug efficiency at RT; 2) realization of a novel type of QC device: the deep-well (DW) QC laser, that has demonstrated at λ = 4.7 µm low temperature sensitivity of the threshold current, a clear indication of suppressed carrier leakage; 3) the formation of 2-D arrays at nanopoles by employing nanopatterning and dry etching; 4) the formation of 40 nm-diameter, one-stage IQB structures on 100 nm centers by preferential regrowth via metal-organic vapor phase epitaxy (MOVPE).

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Magnetopolaron in a weakly elliptical InAs/GaAs quantum dot

Cited by 42 publications

References 35 publications

Optical absorption in quantum dots: Coupling to longitudinal optical phonons treated exactly

Optical absorption in quantum dots: Coupling to longitudinal optical phonons treated exactly

Second-Order Resonant Polaron in a Self-Assembled Quantum Dot

Progress towards intersubband quantum-box lasers for highly efficient continuous wave operation in the mid-infrared

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