Thermal properties and nanoelectromechanical system based on carbon nanotubes

摘要

In Chapter I, the fundamental electronic properties of two-dimensional (2D) graphene and one-dimensional (1D) carbon nanotubes are discussed, along with the carbon nanotube single-electron transistors (SETs). In addition to nanotubes’ extraordinary electronic properties, the phenomena of phonon transport in carbon nanotubes are also notable. In Chapter II, we discuss our experiments probing the thermal properties of multi-walled carbon nanotubes. We exploit the specific breakdown temperature under a large current, which provides an effective thermometer, in conjunction with the known power input to measure the thermal conductivity of the nanotubes. Our results reveal the exceptional micron-scale phonon mean free path at temperatures approaching 900K, and we demonstrate the first evidence for ballistic phonon propagation in nanotubes, reaching a regime where the thermal conductance of nanotubes is limited only by fundamental quantum mechanical limits imposed by their 1D nature.Moreover, the combination of remarkable electrical and mechanical properties makes carbon nanotubes a highly promising candidate for nanoelectromechanical systems (NEMS). In Chapter III, we investigate using doubly clamped suspended single-walled carbon nanotubes as nanomechanical resonators at cryogenic temperatures. Their intrinsic single-electron transistor behavior provides a mixing mechanism to self-detect their motion based on their capacitance to a nearby gate electrode. We exploit our devices to attain an ultrasensitive mass sensor, realizing atomic-scale mass sensing. Finally, in Chapter IV, nanoelectromechanical switches based on using multi-walled carbon nanotubes as nanoscale linear bearings are discussed. First we demonstrate the preparation of the initial OFF state by using electrical breakdown to create gaps in a free-standing MWNT device, while subsequently the ON state is actuated with electrical forces and undergoes linear bearing motion that telescopes the inner shells to bridge the gaps. The switching cycle can be performed in double-walled nanotube devices by restoring the insulating OFF state with a controllable gate voltage. These tubular switches can potentially serve as nonvolatile memory or logic gate elements.