Photoluminescence and bonding structure evolution of amorphous carbon films with laser intensity

• Published in: Physica. B, Condensed matter Condensed matter, 2009-07, Vol.404 (14), p.1920-1923
• Main Authors: Ding, X.L., Li, Q.S., Kong, X.H.
• Format: Article
• Language: English
• Subjects: Amorphous semiconductors; glasses; Condensed matter: electronic structure, electrical, magnetic, and optical properties; DLC films; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photoluminescence; Physics; PLD; Raman
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2009.03.009

The hydrogen-free diamond-like carbon (DLC) films were prepared at different laser intensities by pulsed laser ablating a graphite target in vacuum circumstance at room temperature. By varying the laser intensities from 2.5×10 8 to 7.5×10 8 W/cm 2 the room-temperature photoluminescence (PL) was found in the range of 580–800 nm. The PL integrated intensity was decreased with increase of laser intensity up to 5.0×10 8 W/cm 2 and then was increased thereafter. Over the same laser intensity region a similar variation trend of the deposition rates of films can be observed. The bonding structure of the carbon atoms in the films was characterized by Raman spectroscopy. Raman measurement showed that the sp 2 bonded fraction increased at low or high laser intensity, while reached a minimum value at 5.0×10 8 W/cm 2. The results indicate that laser intensity has a strong influence on the PL properties of the DLC films and the evolution of the PL was deduced to be correlated with the changes of sp 2 fraction.