PREPARATION OF AMORPHOUS DIAMOND-LIKE CARBON BY PULSED-LASER DEPOSITION - A CRITICAL-REVIEW

A critical review of the pulsed laser deposition (PLD) of amorphous di amond-like carbon (DLC) films is presented. A short review of the PLD process is followed by a review of various experimental configurations for DLC deposition and a discussion of the influence of process param eters on the composition and energy of ablated carbon plumes. Particul ar emphasis is given to the relationship between plume properties and film structure and mechanical characteristics. For the first time, a c umulative influence of the laser power density (fluence) and wavelengt h on the formation and properties of DLC films is shown. The influence of bias, additional auxiliary energy, substrate temperature, and the presence of hydrogen is also discussed. A fluence-wavelength region fo r DLC formation is proposed and correlated with the kinetic energy of ablated carbon species. It is shown that lower fluences are required t o produce DLC films when shorter-wavelength lasers are used. The lates t available results on applications of PLD DLC films as protective coa tings for reducing friction and wear are also discussed. Methods are p roposed to improve film adhesion to steel substrates, so that DLC film s can be used in highly loaded friction contacts. Finally, process imp rovements that are necessary to permit scaling up PLD for growing DLC films are outlined.