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Resonance Raman study of He + ion implanted nanostructured ZnS
Author(s) -
Kumar S. Saravana,
Khadar M. Abdul,
Nair K. G. M.,
Dhara S.,
Magudapathy P.
Publication year - 2008
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2056
Subject(s) - raman spectroscopy , exciton , ion , resonance (particle physics) , ion implantation , analytical chemistry (journal) , materials science , chemistry , atomic physics , optics , condensed matter physics , physics , organic chemistry , chromatography
ZnS nanocrytsals of size ∼2.5 nm were prepared by chemical precipitation technique. Pressed pellets of nanostructured ZnS were implanted with He + ions at doses of 5 × 10 14 , 1 × 10 15 and 5 × 10 15 ions/cm 2 . Raman spectra of both unimplanted and He + ion implanted samples were recorded with ultraviolet (UV) excitation. LO, 2LO, 2TO, (LO + TA) and (2TO − TA) modes of ZnS were observed in the resonance Raman spectra of the unimplanted nanostructured ZnS samples. In addition, a surface mode was observed at 294 cm −1 . With the implantation of He + ions, the 2TO mode disappeared and 2LO mode became prominent and this observation was attributed to the decrease in band gap of ZnS nanocrytsals due to ion implantation. The exciton–LO phonon coupling strength was determined from the intensity ratio of 2LO to LO modes and it was observed that the exciton–LO phonon coupling strength increases with increase in implantation dose. In the present work, we report for the first time the observation of 2TO mode in the resonance Raman spectrum of nanostructured ZnS and also the modification of exciton–LO phonon coupling strength of semiconductor nanoparticles by ion implantation. Copyright © 2008 John Wiley & Sons, Ltd.