Synthesis and resonance Raman spectroscopy of CdS nano-wire arrays

Evolution of optical phonons in CdS nanowires, nanobelts, and nanosheets

“…The Raman modes at 301 and 598 cm −1 observed in the ensemble NWs correspond to the A 1 1LO and 2LO phonons, respectively, and are similar to results observed by others. 8,9,[11][12][13]17,18 A weak response at 213 cm −1 and a broad response around 240 cm −1 are also observed. Note that the Raman peak at 521 cm −1 observed in the ensemble NWs is due to the Si substrate.…”

“…10,20 The downward shift of the 1LO phonon energy due to size confinement is negligible for the CdS NWs with diameters larger than 50 nm. 9 For the lattice contraction of the single NB and NS compared to the single NW, we obtain ⌬c / c = −0.37% and −0.56% for the single CdS NB and NS, respectively. For both the freestanding CdSe nanocrystals 10 and the CdS 1−x Se x nanocrystals embedded in glass, 20 the lattice contraction was reported to be larger for smaller nanocrystals.…”

“…3,4 Recent progress in growth techniques which control growth parameters makes possible the synthesis not only of onedimensional nanowires ͑NWs͒ but also of two-dimensional nanobelts ͑NBs͒ and nanosheets ͑NSs͒, providing even more diverse possibilities for optoelectronic applications. [5][6][7][8] The optical properties of nanostructures are influenced by size confinement, 9 strain, 7,10-12 crystallinity, 7 and excitonlongitudinal optical ͑LO͒ phonon interaction. 11,[13][14][15] For instance, the LO phonon energies of CdS NWs with diameters larger than 50 nm do not exhibit quantum confinement effects and are mostly affected by lattice contraction.…”

“…11,[13][14][15] For instance, the LO phonon energies of CdS NWs with diameters larger than 50 nm do not exhibit quantum confinement effects and are mostly affected by lattice contraction. 9,11,12 Lattice contraction can be induced by surface tension during surface reconstruction in the growth of CdS NWs ͑Refs. 11 and 12͒ and CdSe NBs, 7 resulting in a significant increase of the LO phonon energy.…”

Characterization of CdS Nanowires Self-Assembled in a Nanoporous Alumina Template

“…[13][14][15][16] In this paper, however, CdS nanowires were cathodically depos- ited via dc electrodeposition. DC electrodeposition of CdS nanowires is not very commonly done for samples with very narrow pore diameters.…”