Yuegang Zhang

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Direct deposition of graphene on various dielectric substrates is demonstrated using a single-step chemical vapor deposition process. Single-layer graphene is formed through surface catalytic decomposition of hydrocarbon precursors on thin copper films predeposited on dielectric substrates. The copper films dewet and evaporate during or immediately after(More)
Scattering mechanisms in graphene are critical to understanding the limits of signal-to-noise ratios of unsuspended graphene devices. Here we present the four-probe low-frequency noise (1/f) characteristics in back-gated single layer graphene (SLG) and bilayer graphene (BLG) samples. Contrary to the expected noise increase with the resistance, the noise for(More)
In virtue of its superior properties, the graphene-based device has enormous potential to be a supplement or an alternative to the conventional silicon-based device in varies applications. However, the functionality of the graphene devices is still limited due to the restriction of the high cost, the low efficiency and the low quality of the graphene growth(More)
Metal-catalyzed crystallization of amorphous carbon to graphene by thermal annealing is demonstrated. In this " limited source " process scheme, the thickness of the precipitated graphene is directly controlled by the thickness of the initial amorphous carbon layer. This is in contrast to chemical vapor deposition processes, where the carbon source is(More)
Here we report on a scalable and direct growth of graphene micro ribbons on SiO(2) dielectric substrates using a low temperature chemical vapor deposition. Due to the fast annealing at low temperature and dewetting of Ni, continuous few-layer graphene micro ribbons grow directly on bare dielectric substrates through Ni assisted catalytic decomposition of(More)
The authors address the origin of variabilities in graphene devices and how these variabilities contribute to device performance fluctuations and noise. ABSTRACT | Variability effects in graphene can result from the surrounding environment and the graphene material itself, which form a critical issue in examining the feasibility of graphene devices for(More)
Various graphene-based Au nanocomposites have been developed as surface-enhanced Raman scattering (SERS) substrates recently. However, efficient use of SERS has been impeded by the difficulty of tuning SERS enhancement effects induced from chemical and plasmonic enhancement by different preparation methods of graphene. Herein, we developed graphene-based Au(More)
Bismuth vanadate (BiVO4) has been widely regarded as a promising photoanode material for photoelectrochemical (PEC) water splitting because of its low cost, its high stability against photocorrosion, and its relatively narrow band gap of 2.4 eV. However, the achieved performance of the BiVO4 photoanode remains unsatisfactory to date because its short(More)
A dielectric-sheathed carbon nanotube probe, resembling a " nanopencil, " has been fabricated by conformal deposition of silicon-oxide on a carbon nanotube and subsequent " sharpening " to expose its tip. The high aspect-ratio nanopencil probe takes advantage of the small nanotube electrode size, while avoiding bending and buckling issues encountered with(More)
Nb2O5 nanosheets are successfully synthesized through a facile hydrothermal reaction and followed heating treatment in air. The structural characterization reveals that the thickness of these sheets is around 50 nm and the length of sheets is 500 ~ 800 nm. Such a unique two dimensional structure enables the nanosheet electrode with superior performance(More)
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