Photoluminescence and magneto-optical properties of multilayered type-II ZnTe/ZnSe quantum dots |
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Authors: | Igor L Kuskovsky Y Gong GF Neumark MC Tamargo |
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Institution: | 1. Department of Physics, Queens College of CUNY, Flushing, USA;2. Department of Applied Physics & Applied Mathematics, Columbia University, NY, USA;3. Department of Chemistry, City College of CUNY, NY, USA |
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Abstract: | Multilayered Zn–Se–Te structures grown by migration enhanced epitaxy are studied by temperature- and excitation-dependent photoluminescence (PL) as well as magneto-PL. The PL consists of two bands: a blue band, overlaid with band edge sharp lines, dominant at low temperatures and high excitation, and a green band, which appears at elevated temperature and low excitation. Upon varying excitation intensity by four orders of magnitude, the green band peak energy shifts by ∼60 meV, indicating recombination of excitons in type-II quantum dots (QDs); no significant shift is observed for the blue band. Therefore, the green emission is attributed to ZnTe/ZnSe type-II QDs, which co-exist with isoelectronic centers, responsible for the blue and band edge emissions. The existence of type-II ZnTe/ZnSe QDs is further confirmed by magneto-PL, for which the observed oscillations in the PL intensity as a function of magnetic field is explained in terms of the optical Aharonov–Bohm effect. |
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Keywords: | Multilayers Type-II quantum dots Magneto-photoluminescence Aharonov&ndash Bohm effect Zn&ndash Se&ndash Te Sharp lines |
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