Energy relaxation by multiphonon processes in InAs/GaAs quantum dots

Heitz, R.; Veit, M.; Ledentsov, N. N.; Hoffmann, A.; Bimberg, D.; Ustinov, V. M.; Kop’ev, P. S.; Alfërov, Zh. I.

doi:10.1103/physrevb.56.10435

Cited by 443 publications

(274 citation statements)

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“…The effects of confined acoustical 5 and optical phonons ͑including interface ones͒, [5][6][7][8][9][10][11][12][13][14][15] plasmons, [16][17][18] polaronlike states in QDs, 7,19,20 and the Auger-like process 21,22 have been analyzed.…”

Section: Introductionmentioning

confidence: 99%

Quantum dot energy relaxation mediated by plasmon emission in doped covalent semiconductor heterostructures

et al. 2007

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The interaction between interface plasmons within a doped substrate and quantum dot electrons or holes has been theoretically studied in double heterostructures based on covalent semiconductors. The interface plasmon modes, the corresponding dispersion relationship, and the intraband carrier relaxation rate in quantum dots are reported. We find the critical points in the interface plasmon density of states for multilayered structures results in enhanced quantum dot intraband carrier relaxation when compared to that for a single heterostructure. A detailed discussion is made of the relaxation rate and the spectral position dependencies on the quantum dot layer thickness as well as on the dopant concentration. The material system considered was a p-Si/ SiO 2 / air heterostructure with Ge quantum dots embedded in an SiO 2 layer. This structure is typical of those used in technical applications.

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Section: Introductionmentioning

confidence: 99%

Quantum dot energy relaxation mediated by plasmon emission in doped covalent semiconductor heterostructures

et al. 2007

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“…The data is well fit by a single-exponential, yielding lifetimes that agree with conventional time-resolved PL measurements. 12 For all extracted lifetimes, the error is smaller than the plotted symbol size or otherwise noted by error bars. QD spontaneous emission rates have been observed to decrease with increasing QD size 12 despite theoretical predictions that the QD oscillator strength should remain nearly independent of QD size.…”

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confidence: 99%

Coherent coupling dynamics in a quantum-dot microdisk laser

et al. 2002

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Luminescence intensity autocorrelation (LIA) is employed to investigate coupling dynamics between (In,Ga)As QDs and a high-Q (~7000) resonator with ultrafast time resolution (150 fs), below and above the lasing threshold at T = 5 K. For QDs resonant and non-resonant with the cavity we observe both a six-fold enhancement and a 0.77 times reduction of the spontaneous emission rate, respectively. In addition, LIA spectroscopy reveals the onset of coherent coupling at the lasing threshold through qualitative changes in the dynamic behavior and a tripling of the resonant QD emission rate. PACS: 03.67.Lx; 42.55.Sa ; 78.47.+p; The ability to control spontaneous emission 1 in the solid state is expected to improve laser devices 2 as well as enable novel systems for quantum cryptography, such as single photon sources. 3 'Self-assembled' InAs quantum dots (QD)s integrated within high-Q microcavities provide an ideal testbed for studying the control of QD emission through cavity QED (Purcell effect). 4,5 Moreover, understanding the coupling dynamics between the QDs and microcavity may provide an avenue for performing quantum computation and communication with electron spins. 6 Previous measurements in microcavities (i.e.micropillars, 4 microdisks, 5 and microspheres 7 ) have explored enhanced spontaneous QD emission (relative to the unprocessed material), and have yet to investigate the coupling dynamics near the onset of lasing.Here we report time-resolved measurements in microdisks with integrated QDs below and above the lasing threshold using luminescence intensity autocorrelation (LIA) spectroscopy, 8 where the time resolution is theoretically limited by the optical pump/probe pulse widths (~ 150 fs). Detailed studies of the QD-cavity coupling dynamics have shown forQDs resonant and non-resonant with the cavity, a six-fold enhancement and a 0.77 times reduction of the spontaneous emission rate, respectively. Moreover, we use LIA spectroscopy to measure the onset of coherent coupling between the QDs and cavity at the lasing threshold, where we observe a clear signature at zero time delay between pump and probe pulses and an additional tripling of the resonant QD emission rate due to stimulated emission.The device structure is grown by molecular beam epitaxy upon a semi-insulating GaAs substrate with an AlAs/GaAs buffer. A 1 µm layer of Al x Ga 1-x As, (x ranging from 0.65-0.85) is subsequently grown, determining the microdisk post height. The disk region has a single layer of (In,Ga)As self-assembled QDs with a dot density of 10 9 cm -2 and is clad symmetrically by 100 nm GaAs, 20 nm Al 0.3 Ga 0.7 As, and 4 nm GaAs [right inset of Figure 1 where ∆E is the FWHM of the emission energy. The enhancement of the spontaneous emission rate is given by the Purcell factor, 1 F P, (which indicates the degree of coupling between emitter and cavity): F P = (3/4π 2 )(Qλ 3 /V). For our highest Q WGM, with transition energy at 1.378 eV, we estimate F P ~ 50. This calculation assumes an ideal monochromatic 3 emitter that is sp...

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“…In order to obtain optical devices with high performance, it is crucial to understand the optical processes involved in these complex nanostructures. In this sense, the optical properties of InAs/GaAs QDs have been widely investigated by photoluminescence (PL) [14][15][16][17][18][19], photoluminescence excitation spectroscopy (PLE) [15,17], and time-resolved photoluminescence (TRPL) [15,17,20]. However, in spite of the large number of experimental works dealing with the investigation of the fundamental properties of InAs/GaAs QDs, little attention has been paid to the excited states in order to study the dependence of the integrated photoluminescence (IPL) on the excitation-power density (Pexc), which is of great importance to understand the carrier dynamics inside the QDs.…”

Section: Introductionmentioning

confidence: 99%