Regensburg 2000 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 14: Optische Eigenschaften
HL 14.9: Vortrag
Dienstag, 28. März 2000, 11:30–11:45, H13
Phonon replicas in nontunable photoluminescence of Si+-implanted SiO2 — •Horia-Eugen Porţeanu1, Efrat Lifshitz2, Thomas Dittrich1, and Vesselinka Petrova-Koch1 — 1Physik-Department E 16, Technische Universität München, D-85747 Garching, Germany — 2Solid State Institute, Technion Israel Institute of Technology, Technion City, 32000 Haifa, Israel
Samples of Si+-implanted in SiO2, annealed at 1150∘ C, have an efficient photoluminescence band centered at 1.55 eV, independently of the annealing time and consequently on the size of Si nanocrystals. We measured the photoluminescence at 1.4 K in resonant excitation conditions, that shows two phonon steps, shifted by 56 meV and 112 meV from the excitation energy, similar to porous silicon; however with significantly different relative intensities. Based on a quantitative analysis of this measurements and on a comparison with similar measurements of direct semiconductors, we conclude that the existence of phonon replicas does not imply that the luminescence originates from quantized levels in Si-nanocrystals.