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Published online by Cambridge University Press: 17 March 2011
We have investigated the effect of film thickness on the nanoindentation measurements of hard diamondlike carbon (DLC) films. The DLC films were deposited on Si (100) substrates by pulsed excimer laser deposition (KrF, λ=248nm, duration=25 ns, energy density about 3.0 J/cm2, repetition rate 10 Hz) in high vacuum (∼5×10−7torr) at room temperature for various periods of time (from 5 minutes to 20 minutes). The thickness of the films was measured by optical profilometry, and ranges from 200 to 50 nm. The nanohardness and elastic modulus of these films were measured by a depth-sensing nanoindentation technique with NanoindenterXP. Preliminary experimental observations show that the nanoindentation results are a function of film thickness. Both the hardness and Young's modulus versus displacement curves of the 200nm thick film exhibit a peak at around tenth of the film thickness. The rest of the samples with smaller film thickness show plateaus, which are higher than the hardness and Young's modulus values of the substrate.