Carbon nanotube single-electron devices at audio and radio frequencies

Abstract

A single-electron transistor is the most sensitive charge detector known today. It is formed by a small piece of a conductor coupled to electrodes by tunnel junctions. At low frequencies, the charge sensitivity is limited by the 1/f-noise. The use of a radio-frequency modulation technique allows a wide operational bandwidth with negligible 1/f-noise contribution.

In this Thesis, a multiwalled carbon nanotube brought to contact with metal electrodes was demonstrated to work as a single-electron transistor. A scanning probe manipulation scheme was developed and it was used to fabricate the sample. The manipulation scheme was also employed to construct more complicated electronic carbon nanotube devices. It was shown that it is possible to construct a multiwalled carbon nanotube single-electron transistor having an equal to, or even higher charge sensitivity than a typical metallic device. The transmission-line parameters of the multiwalled carbon nanotube were estimated by using the environment-quantum-fluctuation theory.

The radio-frequency single-electron transistor setup was analyzed in depth and a simplified engineering formula for the charge sensitivity was derived. A radio-frequency single-electron transistor setup using a multiwalled carbon nanotube single-electron transistor was demonstrated in the built cryogenic high-frequency measurement system. A low-temperature high-electron-mobility-transistor amplifier was designed and built for the system. Measurements of the amplifier indicated a noise temperature of three Kelvins.