Investigation of the UV/O3 Treatment of Ultrananocrystalline Diamond Films

Surface analytical techniques such as X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and contact angle measurements have been applied to investigate the effects of UV/O3 treatments used to render the original hydrogen termination of ultrananocrystalline diamond/amorphous carbon composite films to an OH-termination. The main parameter varied was the treatment time. For comparison purposes, a sample treated by a microwave O2 plasma for 10 min and a sample treated with UV light without the ozone forming 185 nm emission have been also investigated. The standard UV/O3 treatment leads to the following effects: i) the surface becomes oxidized with a final oxygen surface concentration of about 10%; ii) this oxygen is present at the surface mainly in form of OH groups; iii) the contact angle against purified water drops from 85o for as-grown samples to 5 ± 2o for UV/O3 treated surfaces; iv) the surface energy increases by a factor of two to 78 mN/m; in addition, this surface energy is almost exclusively of polar nature. These developments are almost completed after 20 min of UV/O3 treatment. Similar results can be achieved by O2 plasma treatment, while blocking the ozone forming 185 nm line of the UV lamp leads to only marginal changes of the as-grown surface, thus proving that O3 plays a crucial role in the oxidation process.

KULISCH Wilhelm;  POPOV Cyril;  GILLILAND Douglas;  CECCONE Giacomo;  ROSSI Francois;  REITHMAIER J. P.; 

2010-09-08

JOHN WILEY & SONS LTD

JRC57550

0142-2421,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC57550,   

10.1002/sia.3264,