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International Journal of Photoenergy
Volume 2017, Article ID 4894127, 4 pages
Research Article

Modulation above Pump Beam Energy in Photoreflectance

Insituto de Energía Solar, ETSIT, Universidad Politécnica de Madrid, Avda. Complutense 30, 28040 Madrid, Spain

Correspondence should be addressed to D. Fuertes Marrón; se.mpu.sei@setreufd

Received 19 May 2017; Accepted 27 June 2017; Published 9 July 2017

Academic Editor: Christin David

Copyright © 2017 D. Fuertes Marrón. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Photoreflectance is used for the characterisation of semiconductor samples, usually by sweeping the monochromatized probe beam within the energy range comprised between the highest value set up by the pump beam and the lowest absorption threshold of the sample. There is, however, no fundamental upper limit for the probe beam other than the limited spectral content of the source and the responsivity of the detector. As long as the modulation mechanism behind photoreflectance does affect the complete electronic structure of the material under study, sweeping the probe beam towards higher energies from that of the pump source is equally effective in order to probe high-energy critical points. This fact, up to now largely overseen, is shown experimentally in this work. E1 and E0+ Δ0 critical points of bulk GaAs are unambiguously resolved using pump light of lower energy. This type of upstream modulation may widen further applications of the technique.