Applied Surface Science 257 (2011) 5332–5336 Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc Characteristics of ZrC/ZrN and ZrC/TiN multilayers grown by pulsed laser deposition D. Craciun a , G. Bourne b , G. Socol a , N. Stefan a , G. Dorcioman a , E. Lambers b , V. Craciun a,b,∗ a Laser Department, National Institute for Laser, Plasma, and Radiation Physics, Bucharest, Romania b Major Analytical Instrumentation Center, Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA article info Article history: Received 27 May 2010 Received in revised form 16 November 2010 Accepted 16 November 2010 Available online 24 November 2010 Keywords: ZrC ZrN TiN Pulsed laser deposition Thin films Multilayers abstract ZrC/ZrN and ZrC/TiN multilayers were grown on (1 0 0) Si substrates at 300 ◦ C by the pulsed laser depo- sition (PLD) technique using a KrF excimer laser. X-ray diffraction investigations showed that films were crystalline, the strain and grain size depending on the nature and pressure of the gas used during deposi- tion. The elemental composition, analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), showed that films contained a low level of oxygen contamination. Simulations of the X-ray reflectivity (XRR) curves acquired from films indicated a smooth surface morphology, with roughness below 1 nm (rms) and densities very close to bulk values. Nanoindentation results showed that the ZrC/ZrN and ZrC/TiN multilayer samples exhibited hardness values between 30 and 33 GPa, slightly higher than the values of 28–30 GPa measured for pure ZrC, TiN and ZrN films. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The excellent mechanical properties and thermochemical sta- bility of refractory metal carbides and nitrides recommend them for important applications as hard and protective coatings [1–3]. It is generally rather difficult to deposit high quality ZrC films because of their high melting temperature, low sputtering rate, and high reactivity with oxygen or water vapors [4]. Driven by stringent requirements of special applications, such as coatings for field emission tips, nuclear fuel or outer space thermal radia- tors [5–7], significant progress has been made in the last decade and good quality ZrC films were obtained by using either physical vapor deposition (PVD) or chemical vapor deposition (CVD) based techniques [8–12]. As one of the most versatile research technique, pulsed laser deposition (PLD) allows for relatively low to moderate deposition temperatures of refractory carbides and nitrides with- out sacrificing their crystalline quality [13–15]. Some of the best mechanical properties of ZrC yet reported were measured on films deposited using the PLD technique [16,17]. Furthermore, it has been showed that by using a higher repetition rate laser for ablation, the substrate temperature could be reduced to only 300 ◦ C while ∗ Corresponding author at: Laser Department, National Institute for Laser, Plasma, and Radiation Physics, Bucharest, Romania. E-mail address: vcrac@mse.ufl.edu (V. Craciun). the growth rate is increased and the crystalline quality maintained [18]. The deposition of multilayers with different crystalline lattices that could block at their interfaces the propagation of dislocations from one material to another was shown to be a way of increasing the hardness of such thin film structure [19–22]. Since it is known that generally carbides are more brittle than nitrides and that the refractory metal nitrides exhibit very similar properties to carbides, being also used as hard and protective coatings [1,3,16,23–25], we have investigated ways to further improve the quality of films by depositing multilayers of ZrC and a refractory metal nitride such as ZrN or TiN [26] and present new results here. 2. Experiment The depositions were performed in a PLD system using a KrF excimer laser ( = 248 nm, pulse duration  = 25 ns, 8.0 J/cm 2 fluence, 40 Hz repetition rate) that has been already described in detail elsewhere [18,26]. The films were deposited for tens of min- utes from polycrystalline ZrC, ZrN, and TiN targets (Plasmaterials, Inc.) on p ++ (1 0 0) Si substrates (MEMC Electronic Materials, Inc.) that were cleaned in acetone, then ethanol, rinsed in deionized water, and finally blown dry with high purity nitrogen before being loaded into the deposition chamber. The nominal substrate temperature was set at 300 ◦ C. Depositions were performed under a high purity atmosphere of CH 4 or Ar (2 × 10 -3 to 10 -2 Pa). After 0169-4332/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2010.11.106