DPG Phi
Verhandlungen
Verhandlungen
DPG

Dresden 2006 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

CPP: Chemische Physik und Polymerphysik

CPP 25: POSTER Electronic Structure and Spectroscopy

CPP 25.7: Poster

Thursday, March 30, 2006, 17:00–19:00, P2

Comparison of the Layered Semiconductors GaSe, GaS, and GaSe1−xSx by Raman and Photoluminescence Spectroscopy — •Lothar Kador1, Carmen Pérez León1, Kerim R. Allakhverdiev2, Tarik Baykara2, and Ali A. Kaya21University of Bayreuth, Institute of Physics and Bayreuther Institut für Makromolekülforschung (BIMF), D–95440 Bayreuth, Germany — 2Marmara Research Centre of TÜBITAK, Materials Institute, P. K. 21, TR–41470 Gebze/Koçaeli, Turkey

The room-temperature Raman spectra of single crystals of GaSe, GaS, and mixed compounds GaSe1−xSx with 0.02 ≤ x ≤ 0.8 were measured with a HeNe laser in confocal configuration. The changes in the spectra indicate changes of the crystal structure. The spectra of pure GaSe and of the mixed compound with x = 0.02 show, in addition, pronounced photoluminescence signals blue-shifted from the laser line. Their origin is interpreted as second-harmonic generation in the laser focus causing the formation and radiative decay of Wannier excitons. Two-photon absorption is ruled out, since the effect is absent in the centrosymmetric crystals with x > 0.02. With a green laser whose photon energy is larger than the band gap, strong photoluminescence is also observed in crystals with higher sulfur content.

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2006 > Dresden