Growth and characterization of carbon nanowalls

Abstract

ABSTRACTA typical type of two-dimensional (2D) carbon, carbon nanowalls, was successfully grown a few years ago. Theoretical studies have shown that the open boundaries of the 2D graphite sheets may bring about nano-carbons unique transport and magnetic properties. In this thesis, selective growth of carbon nanowalls was carried out via various methods such as chemical etching, oxygen stripping, focused ion beaming and electron-beam lithography (EBL) to isolate the nanowalls within a region of interest. Growth of carbon nanowalls on patterned electrode using EBL was found to be the best method to selectively grow the nanowalls in localized regions and make electrical contact to them. A series of transport measurements was carried out using both titanium and niobium electrodes of various electrode gaps in a low temperature liquid helium cryostat. Using titanium electrodes, it was found that a narrow energy band gap existing in the carbon nanowalls. Prominent fluctuations were also observed at the temperature range between 2.2 K to 200 K. With niobium electrodes, proximity effect and multiple Andreev reflection were observed in some samples.