Papers by Author: Paul M. Koenraad

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Authors: N. Žurauskienė, Stanislovas Marcinkevičius, G. Janssen, E. Goovaerts, A. Bouwen, Paul M. Koenraad, J.H. Wolter
Authors: Paul M. Koenraad, M.B. Johnson, M. Pfister, H.W.M. Salemink
Authors: Paul M. Koenraad, W. de Lange, F.A.P. Blom, M.R. Leys, J.A.A.J. Perenboom, J. Singleton, W.C. van der Vleuten, J. Wolter
Authors: J.C.M. Henning, Y.A.R.R. Kessener, Paul M. Koenraad, M.R. Leys, W.C. van der Vleuten, J.H. Wolter, A.M. Frens
Authors: J.C.M. Henning, Y.A.R.R. Kessner, Paul M. Koenraad, M.R. Leys, A.P.J. Voncken, W.C. van der Vleuten, J.H. Wolter
Authors: Olga A. Shalygina, Denis M. Zhigunov, Dmitrii A. Palenov, Victor Timoshenko, Pavel K. Kashkarov, M. Zacharias, Paul M. Koenraad
Abstract: We report on the experimental and theoretical studies of population/depopulation dynamics of excitons in the structures with Si nanocrystals in SiO2 matrix (nc-Si/SiO2) under strong optical excitation. The experimental results are explained using a phenomenological model based on rate equations for coupled system of energy donors (excitons) and energy acceptors (erbium ions). Exciton luminescence is found to exhibit superlinear dependence for Er-doped samples. At the same time the Er-related luminescence at 1.5 μm shows a saturation of the intensity and shortening of the lifetime, which are attributed to the population inversion of the Er ions states. The obtained results demonstrate that nc-Si/SiO2:Er systems can be used for applications in Si-based optical amplifiers and lasers, compatible with planar Si-technology.
Authors: N. Žurauskienė, S. Ašmontas, A. Dargys, J. Kundrotas, G. Janssen, E. Goovaerts, Stanislovas Marcinkevičius, Paul M. Koenraad, J.H. Wolter, R.P. Leon
Abstract: We present the results of time-resolved photoluminescence (TRPL) and optically detected microwave resonance (ODMR) spectroscopy investigations of semiconductor quantum dots and quantum wells. The ODMR spectra of InAs/GaAs QDs were detected via modulation of the total intensity of the QDs emission induced by 95 GHz microwave excitation and exciton fine structure was studied. Very long life times (up to 10 ns) of photoexcited carriers were observed in this system using TRPL at low temperatures and excitation intensities promising higher responsitivity of such QDs for quantum dot infrared photodetector development. The effects of proton and alpha particles irradiation on carrier dynamics were investigated on different InGaAs/GaAs, InAlAs/AlGaAs and GaAs/AlGaAs QD and QW systems. The obtained results demonstrated that carrier lifetimes in the QDs are much less affected by proton irradiation than that in QWs. A strong influence of irradiation on the PL intensity was observed in multiple QWs after high-energy alpha particles irradiation.
Authors: Paul M. Koenraad, István Bársony, A.F.W. van der Stadt, J. Perenboom, J.H. Wolter
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