Single reactor deposition of silicon/tungsten oxide core-shell heterostructure nanowires with controllable structure and optical properties

Su Kong Chong, Chang Fu Dee, Saadah Abdul Rahman

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We report the controllable growth of silicon/tungsten oxide (Si/WO3) core-shell heterostructure nanowires via a two-step route using a home-built plasma-assisted hot-wire chemical vapour deposition reactor. Uniform coating of WO3 shell indicates a clear preference for growth on the single crystalline Si nanowires. Structure and crystallinity of the WO3 shell are strongly dependent on the filament temperature (Tf). X-ray diffraction patterns and micro-Raman spectra suggested that there was a structure evolution from amorphous into crystallite WO3 monoclinic structure when Tf was increased to 1300 °C and above. The WO3 shell exhibits stoichiometric tungsten trioxide structure as identified by micro-Raman and X-ray photoemission spectra analyses, which showed only W6+-O vibration modes for the former analysis and W6+ energy band for the latter. Microstructure, crystal lattice, interface and growth orientation of the core-shell nanowires were recognized using a high resolution transmission electron microscopy. Our results showed that the core-shell nanowires had preserved the optical transmittance of Si core at a longer wavelength, while showing an additional transmission band edge at a shorter wavelength due to tungsten oxide coating. Their optical absorption increased to 80% and above in visible region, owing to the one-dimensional Si NWs backbone. Optical band gap of the core-shell nanowires showed a variation from 2.4 to 1.8 eV with Tf. This superior visible light absorption core-shell nanowires architecture subsequently enhanced the photocurrent density of the crystalline WO3 nanostructures. This journal is

Original languageEnglish
Pages (from-to)2346-2353
Number of pages8
JournalRSC Advances
Volume5
Issue number3
DOIs
Publication statusPublished - 2015

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Silicon
Nanowires
Tungsten
Heterojunctions
Optical properties
Oxides
Light absorption
Shells (structures)
Crystalline materials
Coatings
Wavelength
Wave transmission
Optical band gaps
Opacity
Photoemission
High resolution transmission electron microscopy
Photocurrents
Crystal lattices
Crystal orientation
Band structure

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)

Cite this

Single reactor deposition of silicon/tungsten oxide core-shell heterostructure nanowires with controllable structure and optical properties. / Chong, Su Kong; Dee, Chang Fu; Rahman, Saadah Abdul.

In: RSC Advances, Vol. 5, No. 3, 2015, p. 2346-2353.

Research output: Contribution to journalArticle

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