Effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous carbon films prepared by pulsed laser deposition

We have investigated the effect of chamber pressure and atmosphere on the m icrostructure and nanomechanical properties of amorphous carbon thin films prepared by pulsed laser deposition. The amorphous carbon films were deposi ted in various atmospheres such as nitrogen and argon at different chamber pressures. We used Raman spectroscopy to study the bonding characteristics of the deposited amorphous carbon films. Atomic force microscopy and optica l microscopy were utilized to observe the surface conditions and the micros tructures of the deposited films. Nanoindentation measurements were carried out on various samples prepared under different conditions to study the ef fect of chamber pressure and atmosphere on the elastic modulus and nanohard ness of the films. It was found that reduced vacuum leads to formation of a morphous carbon films with reduced elastic modulus and nanohardness. Amorph ous carbon films prepared under higher chamber pressures exhibit an increas ed density of particulates and significantly roughened surface. The results were understood in combination with the optical emission and electrostatic measurements of the laser plasma plume. It was found that the presence of atmosphere decreases the leading edge ionic energies of the species in the laser plasma plume and increases the thermalization of the laser plasma due to an increased possibility of collision. (C) 2001 American Vacuum Society .