J Fusion Energ (2011) 30:447–452 DOI 10.1007/s10894-011-9406-3

1. J Fusion Energ (2011) 30:447–452 DOI 10.1007/s10894-011-9406-3 O R I G I N A L R E S E A R C H Characterization of Diamond: Like Carbon Films Synthesized by DC-Plasma Enhanced Chemical Vapor Deposition Elnaz Vaghri • Zahra Khalaj • Mahmood Ghoranneviss • Majid Borghei Published online: 1 April 2011 Springer Science+Business Media, LLC 2011 Abstract In this paper, diamond-like carbons were pro- duced on tungsten and aluminum substrates by DC plasma enhanced chemical vapor deposition (DC-PECVD) system in a C2H2/H2 gas mixture using C2H2 as source hydrocar- bon and H2 as etching and diluting gas. The operation pressure during the growth and substrates temperature were 15 Torr and 180 C, respectively. Characterization of the DLCs deposited on tungsten and aluminum substrates were carried out by Fourier transform infrared (FTIR) spec- troscopy, scanning electron microscopy (SEM), Raman spectroscopy and Atomic force microscopy (AFM). AFM analysis displayed that the DLCs grown on W substrate has lower roughness than the DLCs deposited on Al substrate and it was smoother. FTIR analysis indicates the existence of C–H vibration mode in the DLCs grown on both of substrates. The Raman spectroscopy shows G peak position and I(D)/I (G) ratio decreased for the DLCs grown on W substrate. The SEM images show diffuse and dense dis- tribution of DLCs in Al and W substrate, respectively. These results shows that the optimum conditions were obtained on W substrate. Keywords DLC FTIR Raman spectroscopy SEM Etching gas E. Vaghri M. Borghei Department of Physics, Karaj Branch, Islamic Azad University, Karaj, Iran . http://www.kiau.ac.ir Z. Khalaj M. Ghoranneviss (&) Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, P.O.Box:14665/678, Tehran, Iran e-mail: Ghoranneviss@gmail.com Introduction Diamond-like carbon is an amorphous carbon material which is classified as hydrogenated amorphous carbon (a-C: H) and unhydrogenated amorphous carbon (a-C) due to its hydrogen amount. It has unique properties such as high hardness, chemical inertness, high wear resistance, high thermal conductivity, low coefficient of friction, optical transparency, etc. [1–5]. One of the significant properties of this structure is the DLC high hardness. Due to this property, we can use it for harden the instruments such as cutting tools, dental tools, drilling instruments, and also as a protective coatings in optical windows, magnetic storage disks, bio- medical coatings, etc. [6–13]. It can also be used for harden the tokomaks and nuclear reactors internal walls. In 1970, Aisenberg and Chabot were the first persons who could prepare such films [14]. The a-C: H films or DLC films can be divided into two different forms the hard a-C: H and the soft one. The hard a-C: H consists of a friction of SP2 bonds and SP3 bonds and low hydrogen amount whereas soft a-C: H has high hydrogen amount. The DLC films can be produced by different methods such as pulse laser deposition (PLD) [15], ion beam deposition [16, 17], cathodic vacuum arc deposi- tion [18, 19], sputtering [20], plasma-enhanced chemical vapor deposition (PECVD) [21], etc. Although there are different CVD methods for growth of diamond and diamond like carbon [22, 23] but two of the most common techniques that applies for the deposition of DLC films are dc- and rf- PECVD method. In most cases, synthesis of the DLC thin films is done by rf- PECVD system [24–26]. However, we have a low stress value in DC-PECVD technique comparison with rf-PECVD [27]. In the PECVD reaction chamber the substrate is placed in the center of the oven which act as a cathode. Possibility of deposition on a large area and at low temperature is the main advantage of the PECVD technique 123