Spectrophotometric Investigation on the Growth Mechanism of a Single Tapered CuO Nanowire
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1206-M16-10
Spectrophotometric Investigation on the Growth Mechanism of a Single Tapered CuO Nanowire
A Chatterjee*, C.-Y. Huang, S.-B. Liu, S.-Y. Wu, C.-L. Cheng Department of Physics, National Dong Hwa University, Hualien, Taiwan E-mail: [email protected]
ABSTRACT
In this study, well separated tapered CuO nanowires have been synthesized on copper grid using an easy and cost effective thermal oxidation method. A set of spectroscopic investigations have been performed on one single tapered CuO nanowire using Energy Dispersive X-ray, confocal Raman and confocal Photoluminescence spectroscopy to get insight into the mechanism of growth of the nanowires. Energy Dispersive X-ray studies reveal crystallization process of CuO nanowires occur from Cu/Cu2O mixed phase state to pure CuO structure. Raman measurements indicate a little sharpening of the Raman peaks with increasing growth temperature of the nanowires starting from 400oC to 600oC. Photoluminescence studies were carried out by mapping along the length of the nanowire to investigate the growth as well as optical properties of a single tapered CuO nanowire. As the diameter of the single tapered CuO nanowire decreases, the green emission of the nanowire gradually shifts towards the higher energy side. A steady blue shift of 20 nm of the photoluminescence peak has been attributed to the nanosize effect of the tapered nanowire along the length and enhanced surface defects.
INTRODUCTION Understanding the growth mechanism of the tapered semiconducting nanowires is essential for the synthesis of nanowires of desired physical and optical properties. Cupric oxide (CuO), a p-type semiconductor is currently considered to be the key structural components of future electronic, optoelectronic, bio and gas sensing devices [1-5]. CuO exhibits an interesting monoclinic structure with narrow band gap (1.2 eV) has emerging to be an exciting subject to study the growth mechanism in one-dimensional confinement regime. Although some studies have been done to grow CuO nanowires by thermal oxidation methods but very less work has been done on probing the optical properties of the nanowire along the growth direction. Raman and Photoluminescence spectroscopy are nondestructive techniques could be employed to monitor the optical properties of the nanowires during the growth process. It can also help to extract information’s about the surface structural properties (defects) of such materials as well. In this paper we report a through investigation on the
growth mechanism of CuO nanowire, by energy dispersive x-ray (EDX) spectroscopy, Raman spectroscopy and photoluminescence (PL) mapping along the length of a single CuO nanowire. This study is valuable to understand the mechanism of growth of the nanowires and defects or surface structural properties of a single tapered CuO nanowire grown by thermal oxidation method.
EXPERIMENTAL
Well separated array of CuO nanowires have been successfully synthesized by thermal oxidation in static air of a copper grid at 5000C for 1 hour [
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