Spectroscopic ellipsometry of carbon nanotube formation in SiC surface decomposition

Abstract

We have studied the initial stage of formation of carbon nanotube layers in surface decomposition of SiC substrate by means of spectroscopic ellipsometry. Before heating, the surface of the SiC substrate was covered with an SiO2 layer that had been formed by natural oxidation. By heating up to 1100 °C, reduction of SiO2 layer occurs. Between 1150 and 1300 °C, the surface of SiC decomposes and a (graphite+void) layer is formed on the surface. Then, by heating at 1300 °C for longer time, a carbon nanotube layer is formed. As a result, we have detected the beginning of the surface decomposition at 1150 °C and the beginning of the formation of a carbon nanotube layer at 1300 °C.