Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Poster Session: GaN - Optical Properties & Preparation and Characterization & Devices

HL 25.9: Poster

Montag, 26. März 2012, 16:00–19:00, Poster D

Optical second harmonic spectroscopy of GaAs excitons in crossed electric and magnetic fields — •David Brunne¹, Marco Lafrentz¹, Victor Pavlov², Roman Pisarev², Dmitri Yakovlev¹, and Manfred Bayer¹ — ¹Experimentelle Physik 2, TU Dortmund, D-44221 Dortmund, Germany — ²Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia

Optical second harmonic generation is a powerful tool to investigate exciton resonances in semiconductors. Recent measurements on GaAs in an external magnetic field have revealed a rich spectrum of magneto-excitons related to carrier Landau levels with numbers up to eight¹. In the present work we extend this research by additional application of an electric field, which modifies considerably the spectrum of magneto-excitons detected via second harmonic generation (SHG). Electric and magnetic fields are applied perpendicular to each other and to the (001) crystal axis of a GaAs sample. In the absence of these fields SHG intensity is zero as the nonlinear process is forbidden in the electric-dipole approximation. Polarization characteristics are analyzed. We discuss the rich spectrum of magneto-excitons which stems from the complex energy and spin structure of the valence band.
¹ V. V. Pavlov, A. M. Kalashnikova, R. V. Pisarev, I. Sänger, D. R. Yakovlev, and M. Bayer, Phys. Rev. Lett. 94, 157404 (2005)