Power dependent photoluminescence of lateral quantum dot molecules: Indication of extended electron states

Lippen, T Twan van; Nötzel, R.; Eijkemans, TJ Tom; Bogaart, EW Erik

doi:10.1002/pssc.200671586

Cited by 2 publications

(3 citation statements)

References 7 publications

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“…Further increasing the excitation power leads to the third peak, located at around 1.3 eV. It can be interpreted that the first two peaks at a lower excitation power arise from the QD with different sizes, and the third peak occurring at a higher excitation power comes from the excited state of the QDs since both the first and the second peaks should be observable with the same intensity ratio [9], but in our case the intensity ratio of the second peak and the third peak is different when the excitation power was increased. Fig.…”

Section: Resultsmentioning

confidence: 91%

“…At 90 K, the integrated PL intensity is highest and the linewidth decreases to 44 meV compared with the 54 meV at 10 K. Further increasing the temperature, the linewidth increases again and the integrated PL intensity reduces. This is due to the electron-phonon scattering and thermal distribu-tion [8][9][10][11][12]. The optical polarization anisotropy of the QD emission was also analyzed by observing the variation of PL signal intensity as the half-wave plate retarder orientation is rotated.…”

Section: Resultsmentioning

confidence: 99%

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Low-Temperature Micro-PL Measurements of InAs Binary Quantum Dots on GaAs Substrate

et al. 2007

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Optical properties of InAs binary quantum dot (bi-QD) molecules grown on the (001) GaAs substrate were measured by means of temperature- and excitation-power-dependent photoluminescence (PL) spectroscopy. It was observed that the shape and peak position of the PL spectra changed with the temperature and with the excitation power. It was also found that the linear polarization degree of the bi-QD PL signal changed with temperature. The temperature-dependent PL described that the linear polarization degree of bi-QDs is closely related to the carrier dynamics.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Low-Temperature Micro-PL Measurements of InAs Binary Quantum Dots on GaAs Substrate

et al. 2007

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“…3 Experimental results Bulk InAs and GaAs have a low piezoelectric constant, however, it has been shown by many groups that self-assembled QDs do induce pronounced piezoelectric fields as a result of the high strain and composition gradients. From excitation density dependent PL measurements, we clearly observe a blue shift [11,18] of the spectrum with increasing density [20]. Hence, the blue shift reveals the strong PZE field within the QD clusters.…”

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confidence: 90%

Carrier‐induced coherent acoustic phonon excitation in strain engineered InAs/GaAs quantum dot clusters

Bogaart¹,

Lippen

Nötzel

et al. 2006

Phys. Status Solidi (c)

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Strain engineered InAs/GaAs quantum dot (QD) clusters grown on (311)B GaAs are studied by means of time-resolved differential reflection spectroscopy revealing coherent excitation of the quasilongitudinal and quasitransverse acoustic phonon modes. Photogenerated carriers which are captured within the ordered lateral QD clusters initiate coherent acoustic phonon excitation, which induces a transient modulation of the local strain-induced piezoelectric field within the QD clusters. The excited acoustic phonons modulate the optical properties of the QDs through the quantum-confined Stark effect, causing oscillations of the reflection signal.1 Introduction The formation of high quality quantum dots (QDs) in well-defined arrangements, that are QD arrays [1-3] and ordered QD groups [4][5][6][7], by self-organized strain engineering provides a challenge in epitaxial crystal growth. The number of QDs within a single group or QD cluster, formed by using strained-layer superlattice (SL) templates [5,6], is controlled by varying the growth temperature of the SL template and the thickness of the GaAs separation layer between the SL template and the QD layer. A consequence of strained nanostructure growth is the strongly enhanced piezoelectric (PZE) field [8,9], which in turn affects the electro-optical properties of the structure [9][10][11][12].We have studied the differential reflectivity of QDs arranged in small ordered groups of 4 QDs per cluster on average, grown by strain engineering [5,6]. Using pump-probe time-resolved differential reflection spectroscopy (TRDR) [13], we are able to measure the carrier capture and carrier relaxation process, and the carrier recombination process within the QDs. For structures with a random QD distribution, the decay of the TRDR signal is described by a single exponential function. In the case of the QD clusters pronounced oscillations in the transient TRDR signals are observed, due to coherent acoustic phonon excitation [14][15][16] within the QD clusters induced by the screening of the local PZE field governed by carrier capture. The phonons are identified as the quasilongitudinal (QL) and quasitransverse (QT) acoustic phonon modes [17]. In turn, the acoustic phonons modulate the local strain and, hence, the strain-induced PZE-field in the QD clusters. Hereby, the optical properties of the QDs, e.g., the QD reflectivity, is periodically changed through the quantum-confined Stark effect [18,19] causing oscillations in the TRDR signal.

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Power dependent photoluminescence of lateral quantum dot molecules: Indication of extended electron states

Cited by 2 publications

References 7 publications

Low-Temperature Micro-PL Measurements of InAs Binary Quantum Dots on GaAs Substrate

Low-Temperature Micro-PL Measurements of InAs Binary Quantum Dots on GaAs Substrate

Carrier‐induced coherent acoustic phonon excitation in strain engineered InAs/GaAs quantum dot clusters

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