Regensburg 2000 – scientific programme
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HL: Halbleiterphysik
HL 14: Optische Eigenschaften
HL 14.7: Talk
Tuesday, March 28, 2000, 11:00–11:15, H13
Excitonic and vibrational properties of CdS/HgS/CdS Quantum Dot-Quantum Wells — •Horia-Eugen Porţeanu1, A. Eychmüller2, M. Pflughoefft2, H. Weller2, and E. Lifshitz3 — 1Physik-Department E 16, Technische Universität München, D-85747 Garching, Germany — 2Institut für Physikalische Chemie, Universität Hamburg, Bundessstr. 45, D-20146 Hamburg, Germany — 3Solid State Institute, Technion Israel Institute of Technology, Technion City, 32000 Haifa, Israel
We analyzed with help of fluorescence line narrowing, photoluminescence, photoluminescence excitation and double beam luminescence the optical properties of a quantum dot - quantum well system consisting of a CdS core (quantum dot) and a HgS intermediate shell as quantum well. We found for one of the samples an anomalous decreasing of Stokes shift with increasing of energy gap. The CdS core measured separately, presents Raman and LO-phonon replicas with different energies. We made the analogy between the latter result and the discrepancy between the LO-phonon replicas and Raman line in quantum dot - quantum well systems suggesting that the higher value as the Raman line can be explained by a k≠ 0 wavevector. The double beam experiment shows a correlation between the saturation of the defect band and an enhancement of excitonic band at high light excitation intensities.