One of the greatest issues of nanoelectronics today is how to control the heating of the components. Graphene is a promising material in this area, and it is essential to study its thermal properties. Here, the effect of heating a bilayer structure was investigated using in situ Raman spectroscopy. In order to observe the effects on each individual layer, an isotopically labeled bilayer graphene was synthesized where the two layers were composed of different carbon isotopes. Therefore, the frequency of the phonons in the Raman spectra was shifted in relation to each other. This technique was used to investigate the influence of different stacking order. It was found that in bilayer graphene grown by chemical vapor deposition (CVD), the two layers behave very similarly for both Bernal stacking and randomly oriented structures, while for transferred samples, the layers act more independently. This highlights a significant dependence on the sample preparation procedure.

The electromechanical properties of arrays of vertically aligned multiwalled carbon nanotubes were studied in a parallel plate capacitor geometry. The electrostatic actuation was visualized using both optical microscopy and scanning electron microscopy, and highly reproducible behaviour was achieved for actuation voltages below the pull-in voltage. The walls of vertically aligned carbon nanotubes behave as solid cohesive units. The effective Young's modulus for the carbon nanotube arrays was determined by comparing the actuation results with the results of electrostatic simulations and was found to be exceptionally low, of the order of 1-10 MPa. The capacitance change and Q-factor were determined by measuring the frequency dependence of the radio-frequency transmission. Capacitance changes of over 20% and Q-factors in the range 100-10 were achieved for a frequency range of 0.2-1.5 GHz.

Post-print of a peer-reviewed article published by Inderscience Publishers.

Ambient room temperature growth of aligned multi-walled carbon nanotube arrays on micrometer scale local heaters is demonstrated. High growth rates of up to 8.8 microm per second have been achieved and the growth has been monitored in situ using optical microscopy. The growth starts and ends abruptly over the length of the local heater. The terminal length of the nanotubes shows a clear dependence on growth temperature and small inhomogeneities in temperature across the heater are seen to lead to interesting microstructure of the arrays. The activation energy for growth was seen to be consistent with earlier reports for acetylene growth of nanotubes on iron catalysts.

Arrays of carbon nanotubes were reversibly actuated by applying a bias voltage. The actuation results in a variable capacitance between the arrays, which can be used to build a varactor. The capacitances were evaluated by simulating the scattering parameters in an equivalent electrical circuit while using the capacitance between the arrays as a fitting parameter. These simulations were compared with radio-frequency (RF) measurements on devices. A very good agreement between measurement and model was obtained. The capacitance could be varied by more than 20 per cent before the arrays were pulled into contact.