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TOMÁNEK, P., DOBIS, P., BENEŠOVÁ, M., GRMELA, L.
Originální název
Near-field optical measurement of carrier recombination in InAs/GaAs quantum dots
Typ
abstrakt
Jazyk
angličtina
Originální abstrakt
The applicability of scanning near-field scanning optical microscopy (SNOM) for optical characterization of semiconductors with InAs/GaAs quantum dots is discussed. Highly uniform and sharply aligned InAs QDs were grown on metastable In-GaAs/GaAs structures with cross-hatched dislocation patterns induced by thermal annealing. Photoexcited carrier dynamics are studied using time-resolved photoluminescence in the optical near-field. Comparison with randomly distributed InAs quantum dots grown on planar substrates shows that different channels are responsible for recombination of free carriers. In the case of aligned QDs, the PL intensity increases superlinearly with excitation power, a clear indication of the importance of non-radiative recombination. The carrier dynamics can be described by a set of rate equations that model the capture of holes and electrons from inside the QDs to the dislocation-related traps and to the point traps close to the quantum dots. Numerical calculations show excellent agreement with the experimental results for all excitation powers. Then changing the barrier of sample from 5 nm to the 10 nm, only the capture rate for the dislocation related traps changes due to the larger distance between dots and dislocations. For the sample with 20 nm barrier, a higher concentration of traps near the dots is needed to explain the short carrier lifetimes in the dots for this sample. It should be noted that when simulations were performed with just one type of trap, independently of its parameters, no good fit to the experiment could be obtained. The correlation of experimental data and calculation leads us to presume that several of the standard optical characterization methods can be coupled with SNOM to provide higher spatial resolution in the local measurements. The applicability of SNOM as a real-time in-situ probe shares some of the problems of other proximal probe methods, but offers enough new capabilities to warrant its application.
Klíčová slova
quantum dot, near-field optics, local spectroscopy, carrier recombination
Autoři
Vydáno
23. 6. 2004
Nakladatel
Vutium, Brno
Místo
Brno
ISBN
80-214-26732-X
Kniha
Material structure & micromechanics of fracture
Strany od
115
Strany do
Strany počet
1
BibTex
@misc{BUT59955, author="Pavel {Tománek} and Pavel {Dobis} and Markéta {Benešová} and Lubomír {Grmela}", title="Near-field optical measurement of carrier recombination in InAs/GaAs quantum dots", booktitle="Material structure & micromechanics of fracture", year="2004", pages="1", publisher="Vutium, Brno", address="Brno", isbn="80-214-26732-X", note="abstract" }