Thermal Laser Epitaxy of Carbon Films

Synthesizing carbon films by thermal evaporation is challenging due to carbon's refractory nature, which entails extremely high evaporation temperatures (>2000 degree celsius). This study investigates thermal laser epitaxy (TLE) as a technique for carbon film growth. We use TLE to grow carbon films on c-plane sapphire substrates in a wide range of substrate temperatures (20-1800 degree celsius). These studies show that the crystallinity of carbon films can be controlled by the substrate temperature during growth, where amorphous and nanocrystalline carbon forms at lower and higher temperatures, respectively. Carbon films grown at high temperatures are electrically more conductive and have smaller activation energies of defect states. Furthermore, this study characterizes the dependence of the growth rate on the power of the source-evaporating laser beam. In addition, it demonstrates in situ growth of carbon films on Ni(111) films on c-plane sapphire substrates. Our results reveal the effectiveness of TLE in synthesizing a broad spectrum of carbon films that range from films of amorphous carbon to nanocrystalline carbon.