Noise spectroscopy of self-aligned carbon nanowalls

Nano-carbon materials are promising for use in future electronic devices. Their superior properties are derived from the low dimensional structure based on the two dimensional carbon (graphene) sheet. Carbon nanowalls (CNWs) are nano-carbon materials comprising a few layers of graphene. However, controlling the position of CNWs in the devices is difficult during the growth process. This is the limitation of CNWs in applications such as field-effect transistors (FETs). We have developed a self-alignment process for CNWs and investigated the growth control of a CNW channel in CNW-FETs. The CNW-FET shows 1/f-type noise in a drain-source current. There are two noise resources in the CNW channels. One relates to environmental noise such as molecular adsorption with large surface area, and the second relates to grain boundary scattering. Higher growth temperatures enlarge the grain size in CNWs, and this results in a decrease in carrier scattering at the grain boundary. Therefore, the drain-source current could increase. In this case, the noise derived from the grain boundary might be small and the total 1/f noise becomes small.