Enhanced Raman spectroscopy induced by surface defects in ripple-like CdS microbelts

Abstract

Both normal and ripple-like CdS microbelts (MBs) were prepared and their optical properties were investigated by photoluminescent and Raman measurements. One emission at ∼510 nm for normal CdS MBs and two emissions around 513 and 725 nm for ripple-like one were observed. The longitudinal optical phonon mode (1LO) at ∼304 cm−1 and its overtone mode (2LO) at ∼605 cm−1, multiphonon processes and surface phonon peaked at 281 cm−1 were observed, the larger integrated intensities ratio of 2LO to 1LO indicates a strong exciton-phonon coupling interaction. Furthermore, more than 4 times larger enhanced Raman scattering for the ripple-like MBs than the normal one were observed, and the enhanced Raman scattering is mainly associated with the surface defects, which lead to a strong Fröhlich interaction through the charge transfer, not by the deformation potential through surface plasmon enhancement.