Multicomponent precursors, e.g. methyltrichlorosilane (MTS) and hexamethyldisilane (HMDS) can function as the source for both Si and C atoms. The alternative are CVD processes with separate silicon and carbon precursors, e.g., silane (SiH 4 ) and silicon tetrachloride (SiCl 4 ) are widely used Si-precursors, whereas short chain hydrocarbons, e.g. methane , propane , ethylene and acetylene , have been utilized as C-precursors.