Premium
Extra Raman modes in CdS during cubic to hexagonal structural transformation
Author(s) -
LozadaMorales R.,
ZelayaAngel O.,
JiménezSandoval S.,
TorresDelgado G.
Publication year - 2002
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.875
Subject(s) - wurtzite crystal structure , raman spectroscopy , metastability , annealing (glass) , lattice (music) , thin film , materials science , cubic crystal system , atmospheric temperature range , ion , condensed matter physics , chemistry , crystallography , hexagonal crystal system , nanotechnology , thermodynamics , optics , physics , metallurgy , organic chemistry , acoustics
Cubic CdS thin films were grown on glass substrates by chemical bath deposition at 80 °C. By means of thermal annealing (TA) in an Ar + S 2 atmosphere in the 224–403 °C range, the cubic metastable zinc blende (ZB) crystalline structure gradually transforms to the stable wurtzite (W) phase. The critical temperature of this phase transformation is around 300 °C, where the material passes from a ZB‐dominated to a W‐dominated phase. Raman spectra obtained at room temperature in parallel and crossed polarizations exhibit extra vibrational modes only when TA is at 344 °C. These experimental findings were explained by considering the critical density of interstitially located Cd 2+ ions and their influence to the lattice dynamics of the system. We assumed a model in which the interatomic bonds in the CdS lattice are physically described by a set of springs obeying Hooke's law. The calculated wavenumbers agree remarkably well with the experimental data considering the simplicity of the approach. Copyright © 2002 John Wiley & Sons, Ltd.