Fluctuation Microscopy Studies of Amorphous Diamond-Like Carbon Films

Abstract Hydrogen-free amorphous diamond-like carbon films have stimulated great interest because of their useful properties, such as high hardness, chemical inertness, thermal stability, wide optical gap, and negative electron affinity[l]. Consequently, they may have various potential applications in mechanical and optical coatings, MEMS systems, chemical sensors and electronic devices. Amorphous diamond-like carbon films often contains significant amounts of four-fold or sp3 bonded carbon, in contrast to amorphous carbon films prepared by evaporation or sputtering which consist mostly of three-fold or sp2 bonded carbon. The ratio and the structure configurations of these three-fold and four-fold carbon atoms certainly decide the properties of these amorphous diamond-carbon films. Although the ratio of three-fold and four-fold carbon has been studied with Raman spectroscopy and electron-loss-energy spectroscopy, very little has been understood regarding key questions such as how the three-fold and the four-fold carbon atoms are integrated in the film, and what structures those three-fold carbon atoms take.