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Composition dependent lattice dynamics in MoSxSe(2-x) alloys.

Authors :: Jadczak, J.
Dumcenco, D. O.
Huang, Y. S.
Lin, Y. C.
Suenaga, K.
Wu, P. H.
Hsu, H. P.
Tiong, K. K.
Source :: Journal of Applied Physics; 2014, Vol. 116 Issue 19, p193505-1-193505-7, 7p, 6 Graphs
Publication Year :: 2014
Abstract: We report on room temperature, polarization-resolved Raman scattering measurements on layered crystals of the series MoS<subscript>x</subscript>Se<subscript>(2-x)</subscript> (0⩽x⩽2) grown by chemical vapor transport technique. The results reveal two distinct sets of features related to the E<superscript>1</superscript><subscript>2g</subscript> and A<subscript>1g</subscript> modes of pure members of series. As composition x changes, the in-plane E<superscript>1</superscript><subscript>2g</subscript>mode shows two-mode behavior, whereas the out-of-plane A<subscript>1g</subscript> mode presents more complex evolution. The MoSe<subscript>2</subscript>-like branch reveals the splitting associated with the altering arrangement of S and Se atoms around Mo and the resulting changes in the dipole moment of the molecule. The X-ray diffraction measurements confirm that the samples are single-phase materials of 2H-type structure over the entire range of the sulfide composition x, while the scanning transmission electron microscopy imaging reveals a random arrangement of the S and Se atoms. Modified random-element-isodisplacement model is adopted to predict the behavior of the individual modes in the alloys. The model successfully confirms the two-mode behavior exhibited by the MoS<subscript>x</subscript>Se<subscript>(2-x)</subscript> series. [ABSTRACT FROM AUTHOR]