2D XANES-XEOL mapping: observation of enhanced band gap emission from ZnO nanowire arrays

Nanoscale ◽  
2014 ◽  
Vol 6 (12) ◽  
pp. 6531-6536 ◽  
Author(s):  
Zhiqiang Wang ◽  
Xiaoxuan Guo ◽  
Tsun-Kong Sham
Keyword(s):  
Band Gap ◽  
Nanowire Arrays ◽  
Zno Nanowire ◽  
Edge Structure ◽  
X Ray ◽  
Zno Nanowire Arrays ◽  
Optical Luminescence ◽  
Order Of Magnitude ◽  
X Ray Absorption ◽  
Mapping Observation

Using two-dimensional X-ray absorption near-edge structure-X-ray excited optical luminescence (2D XANES-XEOL) spectroscopy, it is found that the band gap emission of ZnO nanowire arrays is substantially enhancedi.e.that the intensity ratio between the band gap and defect emissions increases by more than an order of magnitude when the excitation energy is scanned across the O K-edge. Possible mechanisms are discussed.

Origin of luminescence from ZnO/CdS core/shell nanowire arrays

Nanoscale ◽  
2014 ◽  
Vol 6 (16) ◽  
pp. 9783-9790 ◽  
Author(s):  
Zhiqiang Wang ◽  
Jian Wang ◽  
Tsun-Kong Sham ◽  
Shaoguang Yang
Keyword(s):  
Optical Properties ◽  
Chemical Imaging ◽  
Nanowire Arrays ◽  
Nano Composites ◽  
Core Shell ◽  
Edge Structure ◽  
X Ray ◽  
Optical Luminescence ◽  
Scanning Transmission ◽  
X Ray Absorption

Chemical imaging, electronic structure and optical properties of ZnO/CdS nano-composites have been investigated using scanning transmission X-ray microscopy (STXM), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) spectroscopy.

The Role of CdS Buffer Layer in ZnO Nanowire Arrays/SnS Thin Film Solar Cells

2011 ◽  
Vol 335-336 ◽  
pp. 1402-1405
Author(s):  
Zhe Hu ◽  
Wei Guang Yang ◽  
Sheng Liu ◽  
Ke Tang ◽  
Lin Jun Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Buffer Layer ◽  
Measurement System ◽  
Nanowire Arrays ◽  
Thin Film Solar Cells ◽  
Zno Nanowire ◽  
Thermal Evaporation Method ◽  
X Ray ◽  
Zno Nanowire Arrays

SnS is a promising p-type semiconductor material for low-cost and low-toxic solar cells due to its exciting properties, such as high absorption in the visible range, little toxicity, inexpensiveness, and so on. The CdS nano-layer used as buffer layer of ZnO nanowire arrays/CdS/SnS thin film solar cells was prepared by thermal evaporation method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), UV-Vis spectra, Hall effect measurement system and I-V measurement system were used to characterize the ZnO nanowire arrays/CdS/SnS thin film solar cells. It is found that the CdS nano-layer plays a key role in reducing the leakage current.

Soft X-ray excited colour-centre luminescence and XANES studies of calcium oxide

2007 ◽  
Vol 85 (10) ◽  
pp. 853-858 ◽  
Author(s):  
JY Peter Ko ◽  
Franziskus Heigl ◽  
Yun Mui Yiu ◽  
Xing-Tai Zhou ◽  
Tom Regier ◽  
...  
Keyword(s):  
Calcium Oxide ◽  
Density Functional ◽  
X Rays ◽  
Colour Centre ◽  
Time Resolved ◽  
Edge Structure ◽  
Colour Centres ◽  
X Ray ◽  
Optical Luminescence ◽  
X Ray Absorption

In this study, we show that colour centres can be produced by irradiating calcium oxide with soft X-rays from a synchrotron radiation source. Using the X-ray excited optical luminescence (XEOL) technique, two colour centres, F-centre, and F+-centre can be identified. These colour centres emit photons at characteristic wavelengths. In addition, by performing time-resolved XEOL (TRXEOL), we are able to reveal timing and decay characteristics of the colour centres. We also present X-ray absorption near-edge structure (XANES) spectra collected across oxygen K-edge, calcium L3,2-edge, and calcium K-edge. Experimental results are compared with density functional theory (DFT) calculations.Key words: calcium oxide, colour centre, synchrotron, X-ray excited optical luminescence, X-ray absorption near-edge structure.

The origin of luminescence from di[4-(4-diphenylaminophenyl)phenyl]sulfone (DAPSF), a blue light emitter: an X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study

2016 ◽  
Vol 18 (9) ◽  
pp. 6406-6410 ◽  
Author(s):  
Duo Zhang ◽  
Hui Zhang ◽  
Xiaohong Zhang ◽  
Tsun-Kong Sham ◽  
Yongfeng Hu ◽  
...  
Keyword(s):  
Blue Light ◽  
Luminescence Band ◽  
Functional Group ◽  
Edge Structure ◽  
X Ray ◽  
Light Emitter ◽  
Phenyl Sulfone ◽  
Optical Luminescence ◽  
Blue Luminescence Band ◽  
X Ray Absorption

The blue luminescence band of DAPSF is primarily associated with the sulfur functional group.

X-ray-induced synthesis of Au nanoparticles on ZnO nanowire arrays

2019 ◽  
Vol 229 ◽  
pp. 257-262 ◽  
Author(s):  
Mu Sung Lee ◽  
Su Yong Lee ◽  
Do Young Noh ◽  
Hyon Chol Kang
Keyword(s):  
Au Nanoparticles ◽  
Nanowire Arrays ◽  
Zno Nanowire ◽  
X Ray ◽  
Zno Nanowire Arrays

Cathodoluminescence, X-ray excited optical luminescence, and X-ray absorption near-edge structure studies of ZnO nanostructures

2012 ◽  
Vol 90 (3) ◽  
pp. 298-305 ◽  
Author(s):  
Olga Lobacheva ◽  
Patricia L. Corcoran ◽  
Michael W. Murphy ◽  
Jun Young Peter Ko ◽  
Tsun-Kong Sham
Keyword(s):  
Gas Flow ◽  
Branching Ratio ◽  
Optical Emission ◽  
Zno Nanostructures ◽  
Edge Structure ◽  
X Ray ◽  
Synthesis Parameters ◽  
Optical Luminescence ◽  
Carrier Gas Flow ◽  
X Ray Absorption

ZnO nanostructures of various morphologies and crystallinities were fabricated by thermal evaporation from Zn powder in a tube furnace in the presence of oxygen. It was found that the morphology of ZnO nanostructures was affected by synthesis parameters, such as growth temperature, carrier gas flow, and the presence of catalyst on the surface of the substrate. Representative ZnO nanostructures were studied by X-ray excited optical luminescence (XEOL) and cathodoluminescence (CL) methods. The luminescence from these samples exhibits a morphology dependence of the branching ratio of the near band gap (NBG) emission in the UV and defect emission in the green (GE). The appearance of the optical emission also depends on the excitation method. X-ray absorption near-edge structures (XANES) at the O K-edge and Zn L-edge are also presented and their implications discussed.

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