Synthesis of diamond-like-carbon coatings by pulsed laser deposition: optimization of process parameters

In this work, we report on both the microstructural (sp(3) carbon atoms con tent) and the mechanical properties (hardness and elastic modulus) of pulse d laser deposited diamond-like-carbon (DLC) thin films. The sp(3) content o f the films was determined by analysis of the XPS C Is core-level signal, a nd the hardness and elastic modulus were measured by nanoindentation using the continuous stiffness measurement (CSM) technique. By investigating the effect of process parameters, such as deposition temperature and KrF excime r laser intensity on the diamond-like characteristics of the films, we were able to point out that: (1) deposition at 25 degrees C, as opposed to depo sition at 300 degrees C, enhances the diamond-like properties of the coatin gs, (2) the sp3 content increases with laser intensity up to a maximum valu e of about 60% obtained at 7.0 x 10(8) W/cm(2) and (3) the hardness and ela stic modulus of the coatings both increase with laser intensity as they res pectively reach 44 and 375 GPa at 7.0 x 10(8) W/cm(2). It is finally shown that the observed variations in the hardness value and elastic modulus corr elate well with the variations of the sp3 content of the DLC coatings. (C) 1999 Elsevier Science S.A. All rights reserved.