Investigation of properties of Cu containing DLC films produced by PECVD process Neeraj Dwivedi a,b , Sushil Kumar a,n , Hitendra K. Malik b , C. Sreekumar a , Saurabh Dayal a , C.M.S. Rauthan a , O.S. Panwar a a Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), K.S. Krishnan Road, New Delhi 110012, India b Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India article info Article history: Received 1 June 2011 Received in revised form 12 August 2011 Accepted 13 October 2011 Available online 21 October 2011 Keywords: A. Thin films B. Plasma deposition C. Infrared spectroscopy D. Electrical properties D. Mechanical properties abstract Copper containing diamond like carbon (Cu-DLC) thin films were deposited on various substrates at a base pressure of 1  10 3 Torr using a hybrid system involving DC-sputtering and radio frequency- plasma enhanced chemical vapor deposition (RF-PECVD) techniques. The compressive residual stresses of these films were found to be considerably lower, varying between 0.7 and 0.94 GPa and Cu incorporation in these films improve their conductivity significantly. Their structural properties were studied by Raman spectroscopy, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction techniques that clearly revealed the presence of Cu in the DLC structure. Raman analysis yields that Cu incorporation in DLC enhances the graphite-like sp 2 bonding. However, the sp 2 bonding was found to continuously reduce with the increasing C 2 H 2 gas pressure, this may be due to reduction of Cu nanocrystal at the higher pressure. FTIR results inferred various bonding states of carbon with carbon, hydrogen and oxygen. In addition, hydrogen content and sp 3 and sp 2 fractions in different Cu-DLC films were also estimated by FTIR spectra and were correlated with stress, electrical, optical and nano-mechanical properties of Cu-DLC films. The effect of indentation load (4–10 mN) on nano-mechanical properties of these films was also explored. & 2011 Elsevier Ltd. All rights reserved. 1. Introduction Diamond like carbon (DLC) or hard hydrogenated amorphous carbon (a-C:H) is recognized as a promising alternative material for various applications such as cutting tools, wear and hard disk due to its high hardness, low friction coefficient, high thermal conductivity and very high optical transparency in infrared (IR) region [1–7]. The ability to tune various hybridizations states of carbon in DLC by changing process parameters has led recent research into this material for exploring explore its electronic and photovoltaic proper- ties [8–11]. However, poor adhesion of DLC films with the substrate due to high compressive residual stress restricts its widespread applications [12, 13]. It should be noted that the adhesion of DLC films with substrates can be improved by doping of silicon, nitrogen and fluorine (Si, N , F), though at the expense of some of their other properties [14–16]. In contrast, the incorporation of metals into DLC films is an alternative method that improves the adhesion of these films with substrate without affecting their other properties [17–19]. Moreover, lower conductivity in DLC films, which restricts its potential electronic application, can also be resolved by incorporating metal in DLC matrix (as its incorporation in DLC structure may improve the transport properties). Although some reports pertaining to decrease of residual stress with metal addition have already been investigated, there is a lack of literature on the enhancement of transport properties with incorporation of Cu in DLC film. In this paper, the reduction in stress and improvement in transport properties of DLC films due to incorporation of Cu in DLC matrix have been explored. In addition, measured conduc- tivity of different Cu-DLC films are correlated with hydrogen content and C–H based sp 3 and sp 2 fractions. Their structural, morphological and nano-mechanical properties have also been investigated by X-ray photoelectron microscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nanoindentation measurements were performed. 2. Experimental details Cu-DLC films were deposited on various substrates using a combined DC sputtering and RF-PECVD hybrid system. The schematic representation of the deposition unit used for the growth of Cu-DLC films is shown in Fig. 1. Roots and rotary pumps Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jpcs Journal of Physics and Chemistry of Solids 0022-3697/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpcs.2011.10.019 n Corresponding author. Tel.: þ91 11 45608650; fax: þ91 11 45609310. E-mail address: skumar@nplindia.org (S. Kumar). Journal of Physics and Chemistry of Solids 73 (2012) 308–316