NEXAFS study and electrical properties of nitrogen-incorporated tetrahedral amorphous carbon films R. McCann a , S.S. Roy a, T , P. Papakonstantinou a , I. Ahmad a , P. Maguire a , J.A. McLaughlin a , L. Petaccia b , S. Lizzit b , A. Goldoni b a Nanotechnology Research Institute, School of Electrical and Mechanical Engineering, University of Ulster at Jordanstown, Northern Ireland b Sincrotrone Trieste SCpA, S.S. 14 km 163.5 in Area Science Park, 34012 Trieste, Italy Available online 3 March 2005 Abstract Tetrahedral amorphous carbon nitride (ta-C:N) films obtained by filtered cathodic vacuum arc deposition have been investigated by Near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The C K (carbon K) edge NEXAFS spectra clearly revealed the increase of CMN bonds with the increase of nitrogen concentration. The C K edge NEXAFS analysis further showed that the content of the surface defect (mainly C–H bonds) decreased with the increase of nitrogen in the films. As the nitrogen concentration increased a pronounced change in the k* features were observed at the N K (nitrogen K) edge. The origin of the N K edge k* peaks are mainly due to the formation of CMN bonds and nitrogen substitution in the graphite network. Polarization dependent NEXAFS measurements showed an angular distribution of CN bonds. The electrical resistivity of the ta-C:N films decreased at higher nitrogen concentration and this may be from the development of graphite-like structures in these films. The electrical measurements were confirmed further with electrochemical measurements. D 2005 Elsevier B.V. All rights reserved. Keywords: Carbon nitride; Thin film; NEXAFS; Electrical 1. Introduction During the last decade, tetrahedral amorphous carbon (ta- C) has received considerable interest from both scientific and industrial perspectives. Nitrogen has been incorporated into the amorphous carbon (a-C) network to search for the superhard a ˆ-C 3 N 4 material [1]. On the other hand, ta-C:N films were synthesized mainly to adjust optical, electronic, and mechanical properties of ta-C by altering the bonding configurations of fourfold (sp 3 ) and threefold (sp 2 ) carbon sites and the size the sp 2 domains [1–5]. The large complexity and the various hybridization states in carbon nitride films makes it problematic to work out the actual local structure. It is known that in the ta-C films the surface defects or dangling bonds are a major concern for their electronic applications [6]. The electron energy loss spectroscopy (EELS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy are very sensitive to local electronic structure in all amorphous carbon films. A few recent papers [7–13] have focused on the study of the local bonding structure of carbon nitride films using NEXAFS and its analysis has proved to be a powerful tool for the study of the actual bonding states as well as the surface defects in carbon films. However, the relationship between the surface defect and the atomic bond structure in ta-C:N films is not fully understood yet. Also there exists inconsistency in assigning the local bonding configurations in ta-C: N films. In this study, using NEXAFS spectroscopy we aim to obtain more information about the effect of nitrogen on the local bonding states of ta-C:N films deposited by FCVA techniques. Additionally, electrical and electrochemical properties of the films are studied. 0925-9635/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2005.01.032 T Corresponding author. E-mail address: s.sinha-roy@ulster.ac.uk (S.S. Roy). Diamond & Related Materials 14 (2005) 1057 – 1061 www.elsevier.com/locate/diamond