Synthesis of cobalt/diamond-like carbon thin films by biased target ion beam deposition

Cobalt/diamond-like carbon (Co/DLC) composite thin films were synthesized on silicon wafers by biased target ion beam deposition (BTIBD) in which Co was deposited by sputtering a negatively biased Co target using an Ar ion beam and DLC was produced simultaneously by a second ion beam with CH4 as carbon source. The surface morphology, chemical composition and binding states of the synthesised thin films were studied. The as-deposited Co/DLC films are continuous and smooth with a thickness of approximately 150 nm for an hour of deposition. The average roughness is 3.5 ± 0.3 Å and the root-mean squared roughness is 5.3 ± 1.1 Å. The films are low in contaminations and the mass concentration of Co is approximately 24%. Fourier transform infrared spectroscopy and Raman spectroscopy results indicate the Co did not react with C and barely changed the microstructure of DLC. X-ray photoelectron spectroscopy and synchrotron based near-edge X-ray absorption fine structure studies indicate that the Co is in metallic form in the as-deposited films. The preliminary results demonstrate the promise to synthesize high quality Co/DLC composite films by BTIBD.

Research Highlights► Co/DLC composite films were synthesized by biased target ion beam deposition (BTIBD). ► The films are highly smooth and low in contaminations. ► Cobalt is in metallic form in the as-deposited films. ► Results demonstrate the promise to synthesize high quality Co/DLC composite by BTIBD.