Pulsed laser deposition of tetrahedral amorphous carbon films from glassy carbon and graphite targets: a comparative study

Abstract

It is now well known that carbon thin films deposited by pulsed laser ablation at high laser fluences present very interesting properties. However, the strong interaction generates ejection of particles from the graphite target leading to the presence of micron-sized particles embedded in the deposited layer. For applications in optic and microelectronic this pollution is not suitable. A comparative study of KrF laser ablation of graphite and glassy carbon targets and of the deposited films characteristics is presented. In both cases, the ablation plume is investigated by temporally, spatially and spectrally resolved fast photography as a function of laser fluence. The evolutions of the carbon ion kinetic energies and of the threshold fluence of ejected particles apparition are particularly studied. Then, these measurements are correlated with results of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses of deposited layers to optimize the sp3/sp2 ratio and stress of the film. Finally, our results show that particle-free tetrahedral carbon film can be deposited by pulsed laser deposition (PLD) by using glassy carbon target in place of graphite.