Properties of diamond-like carbon films on crystalline quartz and lithium niobate

One-micron thick DLC films are deposited on Y-X cut quartz and Y-cut lithiu m niobate substrates using a plasma-enhanced CVD technique. From the Raman spectra, we find that the films have a small intensity ratio of 'D' to 'G' peak, indicating a high carbon sp(3)/Sp(2) ratio and high hardness characte ristic. The effect of accelerating a surface acoustic wave by the DLC films has been confirmed by comparing two delayed signals from two near-by delay lines. One was coated with the DLC, while the other was kept as the free q uartz or lithium niobate surfaces. It is observed that the one-micron thick DLC films are able to speed up SAW by 2.4% (at 198 MHz) for DLC/quartz and 2.5% (at 430 MHz) for DLC/lithium niobate samples, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.