Fabrication of nano-scale optical patterns in amorphous silicon carbide with focused ion beam writing

Optical patterns as small as 200 nm width have been fabricated in a thin film of amorphous silicon carbide (a-SiC:H) using a focused ion beam microscope, (FIB). Because of the low electric conductivity of a-SiC:H, the diameter of the writing ion beam is broadened by the effect of surface charging which was overcome by depositing a thin layer of gold onto the a-SiC:H film. The topographic and optical contrasts of the patterned thin films have been mapped with scanning near-field optical microscopy. The optical contrast corresponding to nanostructures is 0.2 with an overall increase of the optical density contrast of 0.5 in the irradiated areas. The results of the fabrication of patterns created with FIB on aluminium-coated a-SiC:H films are also briefly presented.