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Ultrafast Electron Dynamics in Ge Quantum Dots

Published online by Cambridge University Press:  10 February 2011

A. Stella
Affiliation:
Istituto Nazionale per la Fisica della Materia – Dipartimento di Fisica “A. Volta”, Università di Pavia, Via Bassi 6. 1-27100 Pavia, Italy
P. Tognini
Affiliation:
Istituto Nazionale per la Fisica della Materia – Dipartimento di Fisica “A. Volta”, Università di Pavia, Via Bassi 6. 1-27100 Pavia, Italy
S. De Silvestri
Affiliation:
Istituto Nazionale per la Fisica della Materia – Dipartimento di Fisica Politecnico di Milano, Centro di Elettronica Quantistica e Strumentazione Elettronica – CNR, Milano, Italy
M. Nisoli
Affiliation:
Istituto Nazionale per la Fisica della Materia – Dipartimento di Fisica Politecnico di Milano, Centro di Elettronica Quantistica e Strumentazione Elettronica – CNR, Milano, Italy
S. Stagira
Affiliation:
Istituto Nazionale per la Fisica della Materia – Dipartimento di Fisica Politecnico di Milano, Centro di Elettronica Quantistica e Strumentazione Elettronica – CNR, Milano, Italy
P. Cheyssac
Affiliation:
Laboratoire de Physique de la Matière Condensèe, URA 190, Université de Nice-Sophia Antipolis, 06108 Nice Cedex, France
R. Kofman
Affiliation:
Laboratoire de Physique de la Matière Condensèe, URA 190, Université de Nice-Sophia Antipolis, 06108 Nice Cedex, France
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Abstract

An analysis of the ultrafast response of Ge quantum dots, with average radii of 4 nm and 16 nm, is reported here. Pump and probe experiments allowed investigation of the wavelength region between 450 and 750 nrm, characterized by the absorption peaks due to the E, and E11 interband transitions. Two different time regimes have been identified: a first one (τ ≤ 1 ps) associated with pump-induced conduction band filling in the τ-L direction in the Brillouin zone; a second one (τ up to 100 ps) associated with band gap renormalization caused by the carrier interaction in the conduction band. Quantum confinement effects show up in terms of sizedependent blueshift of the E11 spectral feature.

Type
Research Article
Copyright
Copyright © Materials Research Society 2000

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References

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