Fabrication & characterization of macroporous CdSe nanostructure via colloidal crystal templating with electrodeposition method |
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Authors: | S H Yeo L K Teh and C C Wong |
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Affiliation: | (1) School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 |
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Abstract: | Large area ordered arrays of macroporous Cadmium Selenide (CdSe) nanostructure, which possesses high refractive index and
negligible absorption in the visible spectrum critical for the realization of photonic band gaps, was prepared via colloidal
templating by galvanostatic electrodeposition. This work investigates the effect of electrodeposition parameters on the macroporous
CdSe nanostructure. Field Emission Scanning Electron Microscope (FESEM) images showed two and three dimensional porous structures,
consisting of interconnected close-packed arrays of pores. For CdSe thin film of thickness less than 1/3 of the diameter of
a polystyrene sphere, it showed a monolayer of circular pores. As for film thickness close to the diameter of the sphere,
the pores adopted irregular rounded triangular shapes. When the film thickness was more than one layer of the colloidal polystyrene
template, the pores were spherical and had the same diameter as the polystyrene spheres. X-ray Diffraction (XRD) showed that
the CdSe films prepared had a cubic structure with nanometer grain size, which was smaller than the diameter of the template
spheres as well as the diameter of the interconnected channels. A range of 45–70 nm thick CdSe films with > 90% optical transmittance
showed that there was negligible absorption at wavelength of 750 nm. In addition, the CdSe thin film exhibited a band gap
energy of 2.07 eV, blue-shifted from the characteristic 1.7 eV of CdSe. This blue-shift characteristic of the deposited CdSe
film further indicated that it was nanocrystalline which is potentially useful in photonic applications. |
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Keywords: | Cadmium Selenide Macroporous Electrodeposition Photonic Band Gap |
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