Raman spectral mapping of self-aligned carbon nanowalls

Carbon nanowalls (CNWs) are a nano-carbon material constructed with a few layers of graphene and thus may exhibit similar properties to graphene. We developed a self-alignment process for the creation of carbon nanowalls using graphoepitaxy, which can be used for the structural fabrication of field-effect transistors. We used Raman spectral mapping to study the mechanism of the self-alignment process. The dependence of growth on temperature and the use of Raman spectra enabled the observation of geometrical catalyst effects and the induction of defects for self-aligned regions. The same effects were observed when analyzing the dependence of deposition on time. For low-temperature growth, which corresponds to the initial growth, the growth of CNW flakes can be observed only on the edge of processed patterns. On the other hand, the self-alignment process should change the shape of the flakes, thereby affecting grain structures and inducing carrier scattering. The use of graphoepitaxy can therefore help in the initial growth, and then mainly induces defects in CNW films. Finally, these defects are cured with the overgrowth.