Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.22: Poster
Thursday, March 26, 2009, 15:00–17:30, P2
Temperature Tuning of Nonlinear Photoluminescence in Gallium Selenide — •Christoph Angermann1, Lothar Kador1, Kerim R. Allakhverdiev2,3, Tarik Baykara2, and Eldar Salaev3 — 1University of Bayreuth, Institute of Physics and BIMF, 95440 Bayreuth, Germany — 2Marmara Research Centre of TÜBİTAK, Materials Institute, P. K. 21, 41470 Gebze/Koçaeli, Turkey — 3Institute of Physics, Azerbaijan National Academy of Sciences, Baku, Azerbaijan
The non-centrosymmetric є modification of the layered semiconductor gallium selenide (GaSe) is characterized by a very high coefficient χ(2) of quadratic optical nonlinearity. Photoluminescence spectra of the material were investigated with a HeNe laser as excitation source, whose quantum energy is slightly lower than the band edge. Hence, the photoluminescence is ascribed to second-harmonic generation in the laser focus causing the excitation of electrons into the conduction band and, subsequently, the formation and radiative decay of Wannier excitons. With increasing temperature, the band edge shifts to lower energies across the laser line. The concomitant strong increase of the photoluminescence signal is interpreted in terms of resonance enhancement of the χ(2) coefficient. The photoluminescence studies are supplemented by Maker fringe data recorded with different cw diode lasers.