arXiv subjects
Publications and source records attributed to Mikko Paalanen.
We have constructed a noise measurement setup for high impedance carbon nanotube samples. Our setup, working in the frequency range of 600 - 900 MHz, takes advantage of the fact that the shot noise power is reasonably large for high impedance sources so that relatively large, fixed non-matching conditions can be tolerated.
Molecular level components, like carbon multiwalled nanotubes (MWNT), show great potential for future nanoelectronics. At low frequencies, only the outermost carbon layer determines the transport properties of the MWNT. Due to the multiwalled structure and large capacitive interlayer coupling, also the inner layers contribute to the conduction at high frequencies. Consequently, the conduction properties of MWNTs are not very far from those of regular conductors with well-defined electrical characteristics. In our work we have experimentally utilized this fact in constructing various nanoelectronic components out of MWNTs, such as single electron transistors (SET), lumped resistors, and transmission lines. We present results on several nano- tube samples, grown both using chemical vapor deposition as well as arc-discharge vaporization. Our results show that SET-electrometers with a noise level as low as 6x10^{-6}e/\sqrt{Hz} (at 45 Hz) can be built using arc-discharge-grown carbon nanotubes. Moreover, short nanotubes with small contact areas are found to work at 4.2 K with good gate modulation. Reactive ion etching on CVD tubes is employed to produce nearly Ohmic components with a resistance of 200 kOhm over a 2 micron section. At high frequencies, MWNTs work over micron distances as special LC-transmission lines with high impedance, on the order of 5 kOhm.