Aurélien Sikora

Structure of diamondlike carbon films deposited by femtosecond and nanosecond pulsed laser ablation

The characterization of diamondlike carbon (DLC) films is a challenging subject, considering the diversity of carbon-based nanostructures depending on the deposition process. We propose to combine multiwavelength (MW) Raman spectroscopy and electron energy-loss spectroscopy (EELS) to probe the structural disorder and the carbon hybridizations of DLC films deposited by pulsed laser ablation performed either with a nanosecond laser (film labeled ns-DLC), either with a femtosecond laser (film labeled fs-DLC). Such deposition methods allow to reach a rather high carbon sp3 hybridization but with some significant differences in terms of structural disorder and carbonaceous chain configurations. MW Raman investigations, both in the UV and visible range, is a popular and nondestructive way to probe the structural disorder and the carbon hybridizations. EELS allows the determination of the carbon plasmon energy in the low-loss energy region of the spectra, as well as the fine structure of the ionization threshold...

Depth-dependence of electrical conductivity of diamondlike carbon films

The electrical behavior of diamondlike carbon (DLC) has been measured as a function of depth. The amorphous carbon (a-C) films are deposited by pulsed laser deposition using two complementary setups: a femtosecond (fs) and a nanosecond (ns) pulse lasers. It is demonstrated through four probe resistance measurements and contact resistance mapping that the fs DLC are electrically heterogeneous in thickness. The presence of a thick sp2 rich layer on top is evidenced for fs a-C and is apparently away in the sp3 rich ns a-C. It is attributed to different subplantation processes between ns and fs a-C films.