Thickness dependence of the structure of diamond-like carbon films by Raman spectroscopy

✍ Scribed by Fan-Xin Liu; Zhen-Lin Wang

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 610 KB
• Volume: 203
• Category: Article
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2009.01.008

✦ Synopsis

The thickness dependence on structure of Diamond-like carbon films of a-C:H deposited by ECR-CVD and ta-C by FCVA has been studied by visible and UV Raman spectroscopy. The results show that the evolution of structure as a function of the thickness for a-C:H films contains two stages: when thickness is less than 50 Å, the film contains less sp 3 sites and not continuous; and when thickness is up to 50 Å, the film contains more sp 3 sites and become continuous. However, for ta-C films, it includes three stages. In the first stage of thickness lower than 20 Å, the film is not continuous, and also contains less sp 3 . In the second stage of thickness between 20 Å and 50 Å, the sp 3 site abruptly shifts a higher value in 20 Å and then keeps stable. In the third stage of thickness over 50 Å, the sp 3 site has a little increase and then almost not changed. Thus, the fundamental limitation thickness in using DLC as an ultrathin overcoat for ta-C films is 20 Å (N10 Å), and for a-C:H films is 50 Å. The implications of result on the mechanisms proposed for the film growth mode were also discussed.