Nonresonant radiative exciton transfer by near field between quantum wells
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IC PROPERTIES OF SOLID
Nonresonant Radiative Exciton Transfer by Near Field between Quantum Wells V. Ya. Aleshkina,c, L. V. Gavrilenkoa,c,*, D. M. Gaponovaa, A. M. Kadykova, V. G. Lysenkob, and Z. F. Krasil’nika,c a
Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhni Novgorod, 603950 Russia b Institute of Microelectronics Technology and HighPurity Materials, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia c Lobachevskii State University, Nizhni Novgorod, 603950 Russia *email: [email protected] Received May 7, 2013
Abstract—We experimentally observed an increase in the intensity of photoluminescence from a wider quan tum well (QW) when an exciton transition was induced in the neighboring narrower QW separated from the former one by a tunnelingnontransparent AlGaAs barrier. The dependence of the efficiency of the nearfield radiative transfer of excitons on the distance between QWs was studied in heterostructures without coinci dence of exciton resonances in the adjacent QWs. Theoretical results were qualitatively consistent with the available experimental data. DOI: 10.1134/S1063776113130013
1. INTRODUCTION Processes involved in the transfer of excitations due to tunneling and thermal activation of charge carriers are well known and used in practice. The situation is not as clear in respect of the process of excitation transfer via tunnelingnontransparent barriers. Some experimental data have been reported on the transfer of excitations between excitonic states in quantum wells (QWs) and quantum dots (QDs) separated by broad tunnelingnontransparent barriers [1–5]. The mechanisms proposed for the description of excitation transfer via broad tunnelingnontranspar ent barriers were most frequently based on the Förster model [6–9]. This model describing a nonradiative electrostatic interaction between dipoles was used to explain the quenching of excited states in impurity atoms and other point defects by means of excitation transfer to another atom or defect. In heterostructures based on directbandgap semi conductors such as GaAs, the probability of radiative recombination of charge carriers is quite high (with radiative lifetimes below 1 ns) and, hence, one must take into account the possible radiative transfer of excitations in these systems. For example, Muljarov et al. [10] observed reabsorption of excitonic photolumi nescence (PL) in a heterostructure with two QWs of different widths spaced by 60 nm. A resonant coinci dence of the emission line of a heavy hole exciton in a narrow QW and the emission line of a light hole exci ton in a wide QW rendered this reabsorption process observable. Sibeldin et al. [11] observed a stronger effect of the radiative exciton transfer in a heterostruc
ture with three QWs of different widths, where pairwise coincidences of the emission lines of heavy hole exci tons (in narrower QWs) and the emission lines of light hole excitons (in wider QWs) also took place. It is important to note that, in the latter case, the QW
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