Mark C. Rosamond

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We report direct imaging of nanoscale thermal transport in single and few-layer graphene with approximately 50 nm lateral resolution using high vacuum scanning thermal microscopy. We observed increased heat transport in suspended graphene where heat is conducted by ballistic phonons, compared to adjacent areas of supported graphene, and observed decreasing(More)
A single microelectrode array platform, divided into groups of microelectrodes with flexible multiplexing can enable a 'defective' cluster of microelectrodes to be readily identified, by comparing normalised currents with the numbers of microelectrodes in the groups of arrays. This generic design principle may be extended for integrating multiple analyte(More)
Terahertz frequency time-domain spectroscopy employing free-space radiation has frequently been used to probe the elementary excitations of low-dimensional systems. The diffraction limit, however, prevents its use for the in-plane study of individual laterally-defined nanostructures. Here, we demonstrate a planar terahertz frequency plasmonic circuit in(More)
Langmuir-Blodgett deposition has been used to form thin film networks of both metallic and semiconducting single-walled carbon nanotubes. These have been investigated to understand their physical, optical, and morphological properties. The electrical conductivities over the temperature range 80-350 K and across electrode gaps of 220 nm and 2 mm have been(More)
Transparent electrodes are used to provide electrical contacts to the active layers of opto-electronic devices such as organic light emitting diodes, flat panel displays and solar cells. These electrodes should possess high optical transparency and low sheet resistance. Traditionally, tin doped indium oxide (ITO) is used for this purpose. Unfortunately,(More)
The benefits of a new electrochemical etching method for the controlled sharpening of sub-micron tungsten probes are demonstrated. The proposed technique only utilizes the insulating effect of the WO₄(2-) by-product which offers more practical ways of controlling the process parameters. The electrosharpening method was fully automated through the analysis(More)
We present an experimental proof of concept of scanning thermal nanoprobes that utilize the extreme thermal conductance of carbon nanotubes (CNTs) to channel heat between the probe and the sample. The integration of CNTs into scanning thermal microscopy (SThM) overcomes the main drawbacks of standard SThM probes, where the low thermal conductance of the(More)
The emission mechanism of continuous wave (CW) terahertz (THz) photomixers that make use of nanostructured gratings (NSGs) is studied. Two different photomixer designs, based on a single-sided NSG and a double-sided NSG, embedded in the same antenna design and fabricated on an Fe doped InGaAsP substrate, are characterized with ~1550 nm excitation. They are(More)
We present an on-chip time domain terahertz (TD-THz) system in which picosecond pulses are generated in low-temperature-grown gallium arsenide (LT-GaAs) and detected in graphene. The detected pulses were found to vary in amplitude, full width at half maximum (FWHM), and DC offset when sampled optically at different locations along a 50-μm-long(More)
We report on the design and performance of a micro-rectenna device for harvesting wasted thermal energy. As an individual rectenna exhibits low efficiency and output power, we designed and studied a focal plane array (FPA) on a single semiconductor chip. Our FPA could be used for more general energy-harvesting applications as well as for THz imaging.