A comprehensive Raman resonance scattering study of ZnSxSe1-x (ZnSSe) solid solutions over the whole compositional range (0 ≤ x ≤ 1) has been carried out using 325 and 455 nm excitation wavelengths. The Raman scattering intensities of LO ZnS-like and ZnSe-like phonon modes, corresponding to pure S and Se vibrations, respectively, are revealed to be significantly enhanced when excited with 325 nm excitation in the case of S vibrations, and with 455 nm in the case of Se vibrations. This behavior is explained by the interaction of the excitation photons with the corresponding S or Se electronic states in the conduction band, and further confirmed by first principles simulations. These findings advance the fundamental understanding of the coupling between the electronic transitions and photons in the case of Raman resonance effects, and provide inputs for further studies of lattice dynamics, especially in the case of chalcogenide materials. Additionally, the coexistence of modes corresponding to only S vibrations and only Se vibrations in the ZnSSe alloys makes these results applicable for the compositional assessment of ZnSSe compounds.
Bibliographical noteFunding Information:
The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union''s Seventh Framework Program FP7/2007-2013/under REA grant agreement no. 316488 (KESTCELLS). The authors from IREC and IN2 UB belong to the M-2E (Electronic Materials for Energy) Consolidated Research Group and the XaRMAE Network of Excellence on Materials for Energy of the "Generalitat de Catalunya". E.S. thanks the Government of Spain for the "Ramon y Cajal" fellowship (RYC-2011-09212) and H. X. thanks support from the "China Scholarship Council" fellowship (CSC No. 201206340113). A.J.J. is funded by the EPSRC Doctoral Training Centre in Sustainable Chemical Technologies (EP/G03768X/1). A.W. acknowledges support from the Royal Society and the ERC (grant no. 277757). DFT calculations made use of UK national facility ARCHER, via A.J.J. and A.W.''s membership of the UK''s HPC Materials Chemistry Consortium which is funded by EPSRC grant EP/L000202, and of the University of Bath''s HPC facilities.
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