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V. G. Talalaev, A. A. Tonkih, N. D. Zaharov, A. V. Senicev, J. W. Tomm, P. Werner, B. V. Novikov, L. V. Asryan, B. Fuhrmann, J. Schilling, H. S. Leipner, A. D. Buravlev, Ju. B. Samsonenko, A. I. Hrebtov, I. P. Sosmikov, G. E. Zyrlin
Svetoizlucajuscie tunnel'nye nanostruktury na osnove kvantovyh tocek b matrice krenija i arsenida gallija (in Russian).
Fiz. tehn. poluprovod. 46, 11 (2012), 1492-1503

Light-emitting heterostructures InGaAs/GaAs and Ge/Si have been studied. Their active region consists of the system comprising nanoobjects with different dimensions: layers of quantum dots, quantum wells and tunnel barrier. The carrier exchange, that precedes their radiative recombination, is studied in the context of tunnel interaction of nanoobjects. The exciton mechanism of tunneling was established for the ?quantum well ? InGaAs gunatum dot layer? system. In such structures having the barrier thickness of < 6 nm an anomalously fast transfer of carriers (excitons) from the quantum well has been observed. The role of the above-barrier state resonance is discussed. It can provide a ?momentary? injection into quantum dots. In the Ge/Si structures Ge quantum dots have been produced, which have a height comparable with the Ge/Si interface diffusiveness. The intensive luminescence of such structures at 1.55 ?m is explained not only by the high density of island array. The model is based on: (i) the increase of the exciton oscillator strength resulting from the electron penetration into the quantum dot core by tunneling at low temperature; (ii) redistribution of electron states in the Delta2 - Delta4 subbands, when temperature increases to ambientone. Light-emitting diodes have been manufactured on the basis of studied structures of both types. The diodes have been used for testing the design options of active region. It has been demonstrated that the selective pumping of the injector and tunnel transfer of ?cold? carriers (excitons) are more effective than their direct capture into the nanoemitter.

Keywords: quantum dots, radiative recombination, luminescence

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