Spatial variability in large area single and few-layer CVD graphene

Abstract Correlations between the level of p-doping exhibited in large area chemical vapour deposition (CVD) graphene field effect transistor structures (gFETs) and residual charges created by a variety of surface treatments to the silicon dioxide (SiO2) substrates prior to CVD graphene transfer are measured. Beginning with graphene on untreated thermal oxidised silicon, a minimum conductivity (σ min ) occurring at gate voltage V g = 15 V (Dirac Point) is measured. It was found that more aggressive treatments (O2 plasma and UV Ozone treatments) further increase the gate voltage of the Dirac point up to 65 V, corresponding to a significant increase of the level of p-doping displayed in the graphene. An electrowetting model describing the measured relationship between the contact angle (θ) of a water droplet applied to the treated substrate/graphene surface and an effective gate voltage from a surface charge density is proposed to describe biasing of V g at σ min and was found to fit the measurements with multiplication of a correction factor, allowing effective non-destructive approximation of substrate added charge carrier density using contact angle measurements.

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Large-area CVD graphene as transparent electrode for efficient organic solar cells

2012 38th IEEE Photovoltaic Specialists Conference ◽

10.1109/pvsc.2012.6318244 ◽

2012 ◽

Cited By ~ 1

Author(s):

Golap Kalita ◽

Koichi Wakita ◽

Masayoshi Umeno ◽

Yasuhiko Hayashi ◽

Masaki Tanemura

Keyword(s):

Solar Cells ◽

Organic Solar Cells ◽

Transparent Electrode ◽

Large Area ◽

Cvd Graphene

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Addressing Spatial Variability of Surface-Layer Wind with Long-Range WindScanners

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-14-00123.1 ◽

2015 ◽

Vol 32 (3) ◽

pp. 518-527 ◽

Cited By ~ 18

Author(s):

Jacob Berg ◽

Nikola Vasiljevíc ◽

Mark Kelly ◽

Guillaume Lea ◽

Michael Courtney

Keyword(s):

Spatial Variability ◽

Long Range ◽

Three Dimensional ◽

Proof Of Concept ◽

Large Area ◽

Vertical Velocity Component ◽

Sonic Anemometers ◽

Wind Measurements ◽

The Mean

AbstractThis paper presents an analysis of mean wind measurements from a coordinated system of long-range WindScanners. From individual scan patterns the mean wind field was reconstructed over a large area, and hence it highlights the spatial variability. From comparison with sonic anemometers, the quality of the WindScanner data is high, although the fidelity of the estimated vertical velocity component is significantly limited by the elevation angles of the scanner heads. The system of long-range WindScanners presented in this paper is close to being fully operational, with the pilot study herein serving not only as a proof of concept but also verifying expectations of reliable wind measurements over arbitrary three-dimensional volumes, in future sustained meteorological campaigns.

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