Light-Induced Plasmon-Assisted Phase Transformation of Carbon on Metal Nanoparticles

Highly localized light-induced phase transformation of electron beam induced deposited carbon nanostructures (dots and squares) on noble metal surfaces is reported. The phase transformation from the amorphous phase to the disordered graphitic phase is analyzed using the characteristic Raman signatures for amorphous and graphitized carbon and conductive force microscopy. The extent of the transformation is found to be largely dependent on the plasmon absorption properties of the underlying metal film. It is observed that the amorphous carbon deposits on the silver films consisting of 12 nm particles with the plasmon absorption near the laser excitation wavelength (514 nm), undergo fast graphitization to a nanocrystalline or a disordered graphitic phase. This transformation results in the formation of a highly conductive carbon/metal interface with at least seven orders of magnitude lower electrical resistivity than the initial insulating interface. It is suggested that the fast graphitization of nanoscale carbon deposits might serve as an efficient path for the formation of complex patterned nanoscale metal-carbon interconnects with high electrical conductivity.