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Strain-symmetrized Si/SiGe multi-quantum well structures grown by molecular beam epitaxy for intersubband engineering |
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| Authors: | M. Zhao A. Karim C.R. Pidgeon D. Carder T. Fromherz |
| Affiliation: | a Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden b National Nano Device Laboratories, Hsinchu 300, Taiwan, ROC c Department of Physics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK d Department of Physics, University of Surrey, Guildford GU2 7XH, UK e Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, A-4040 Linz, Austria f Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 0HE, UK |
| Abstract: | Three strain-symmetrized Si/SiGe multi-quantum well structures, designed for probing the carrier lifetime of intrawell intersubband transitions between heavy hole 1 (HH1) and light hole 1 (LH1) states with transition energies below the optical phonon energy, were grown by molecular beam epitaxy at low temperature on fully relaxed SiGe virtual substrates. The grown structures were characterized by using various experimental techniques, showing a high crystalline quality and very precise growth control. The lifetime of the LH1 excited state was determined directly with pump-probe spectroscopy. The measurements indicated an increase of the lifetime by a factor of ∼2 due to the increasingly unconfined LH1 state, which agreed very well with the design. It also showed a very long lifetime of several hundred picoseconds for the holes excited out of the well to transit back to the well through a diagonal process. |
| Keywords: | 61.10.Nz 68.37.Lp 78.47.+p 71.20.-b |
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