Surface energy of metal containing amorphous carbon films deposited by filtered cathodic vacuum arc

P. Zhang, Beng Kang Tay, G. Q. Yu, S. P. Lau, Yong Qing Fu

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

Metal containing amorphous carbon (a-C:Me) films including a-C:Al, a-C:Ti, a-C:Ni, a-C:Si were prepared by the filtered cathodic vacuum arc (FCVA) technique with metal-carbon (5 at.% metal) composite targets. The substrate bias ranging from floating to 1000 V was applied. The wettability of the films was examined using the VCA Optima system from AST Products, Inc. Three types of liquid with different polarities were used to study the surface energy changes of the films. X-ray photoelectron spectroscopy (XPS) was used to analyze the composition and chemical state of the films. Atomic force microscopy (AFM) was employed to characterize the morphology and roughness of the films. The contact angle of the a-C:Me films remains relatively constant with different substrate bias. The Al containing films show the highest contact angle with water, which reaches as high as 101°. The Si containing films show the lowest contact angle approximately 64°. The contact angles of Ni and Ti containing films are approximately 80°, 97°, respectively. The harmonic-mean method was used to calculate the polar and depressive component of the surface energy. The absorption of oxygen on the surface plays an important role on the polar component of the a-C:Me films. The formation of AlO and TiO bonds is responsible for their lower polar component. The metal state Ni results in higher polar component. However, the SiO bond is contributed to the high polar component of a-C:Si films. As all films are atomic scale smooth, the RMS roughness is below 0.5 nm, the roughness does not have obvious effect on the surface energy.
Original languageEnglish
Pages (from-to)459-464
JournalDiamond and Related Materials
Volume13
Issue number3
DOIs
Publication statusPublished - Mar 2004

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