| Autor: |
León, C. Pérez, Kador, L., Allakhverdiev, K. R., Baykara, T., Kaya, A. A. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 11/15/2005, Vol. 98 Issue 10, p103103, 5p, 4 Graphs |
| Abstrakt: |
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 pronounced photoluminescence signals blueshifted from the laser line, whereas these signals do not appear for higher sulfur content. 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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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