Raman spectra of misfit layer semiconductor structure (PbS)0.59TiS2 under variation of laser power

Sergey V. Ovsyannikov 1Vladimir V. Shchennikov 1Andres Cantarero 2Ana Cros 2Alexander N. Titov 1

1. Institute of Metal Physics, Urals Division of Russian Academy of Sciences, Kovalevskaya 18, Yekaterinburg 620219, Russian Federation
2. Materials Science Institute, Valencia University, Valencia, Spain

Abstract

In the present work we studied the variation of Raman spectra in misfit layer semiconductor structure (PbS)0.59TiS2 under variation of laser power. The spectra were excited with 514.5 and 488.0 nm laser lines. At the low laser powers the spectra exhibited: (i) two softened (in comparison with TiS2 crystal) phonons of TiS2 host layers at 219 and 333 cm-1; (ii) LO(Γ), 2LO and 3LO phonons from the incommensurate PbS layers at 203.5, 412 and 634 cm-1, respectively; and (iii) a possible superposition mode of PbS and TiS2 layers at 292 cm-1. A process of the misfit’s surface oxidation was investigated under increase of both laser power and time of exposition of the samples under the laser irradiation. The novel wave numbers were observed related to PbO, TiO2, PbO2, PbSO4, “PbO*PbSO4” complexes, and to other oxysulfates at ~ 140, 183, 254, 280, 364, 391, 434, 511, 605 cm-1. A nature is discussed of a peak at 151 cm-1 appearing at high laser powers. In the low-frequency Raman spectra of the misfit (PbS)0.59TiS2 the peculiarities at 19, 73 and 95-96 cm-1 were observed associated with vibrations of the PbS layers.

The work was supported by the INTAS (Nr. 03-55-629) and RFBR (Gr. No. 04-02-16178).

 

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Presentation: poster at E-MRS Fall Meeting 2005, Symposium F, by Sergey V. Ovsyannikov
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-04-18 11:15
Revised:   2009-06-07 00:44