Electronic properties of amorphous carbon nitride a-C 1x N x :H films investigated using vibrational and ESR characterisations M. Lacerda a, * , M. Lejeune b , B.J. Jones c , R.C. Barklie c , R. Bouzerar b , K. Zellama b , N.M.J. Conway a , C. Godet a a LPICM, UMR 7647-CNRS, Ecole Polytechnique, 91128 Palaiseau cedex, France b LPMC, Universit e de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens cedex, France c Department of Physics, Trinity College, Dublin 2, Ireland Abstract A combination of electron spin resonance and Raman spectroscopy measurements is applied to fully characterise a- C 1x N x :Hfilms(x 6 20 at.%), grown by plasma decomposition of C 2 H 2 –N 2 mixtures. The observed decrease in the spin density (8:5  10 19 –1:6  10 19 cm 3 ) when the N content increases is consistent with the decrease in the disorder of the sp 2 nanostructure evidenced by resonant Raman spectroscopy (at 488 and 514.5 nm excitations), which shows an in- crease in the I D =I G ratio and a narrowing of the D-peak. Ó 2002 Published by Elsevier Science B.V. PACS: 78.30.Ly; 63.50.+x; 61.43.Dq 1. Introduction Much effort has been devoted to the study of amorphous carbon nitride (a-C 1x N x :H) films be- cause of their remarkable mechanical and trib- ological properties and more recently for their potential applications as electronic materials in cold cathode displays and in electrochemical stud- ies of water treatments [1–3]. The properties of a-CN x :H films are strongly dependent on the bonding configurations of carbon and nitrogen [1,2,4,5]. The effects of the nitrogen incorporation in the film depend on whether the N atoms enter the sp 2 clusters, by modifying the p-bond states distribution, or the sp 3 network. It is found that the nitrogen incorporation decreases the band gap and increases the conductivity of the films [6,7]. Morerecentresultsreportedfora-C 1x N x :Hgrown by integrated distributed electron cyclotron reso- nance (IDECR) plasma deposition [2] show that forNatomicconcentrationsvaryingfrom0.7to28 at.%, the room temperature conductivity r RT increases by about five orders of magnitude (10 9 –10 4 X 1 cm 1 ) and the activation energy E r associated with r decreases from 0.46 to 0.24 eV. Furthermore, it is found that for (N/ N+C) P 5 at.%, E r reaches a saturation value (0.24 eV) while the conductivity prefactor r 0 increases continuously (10 2 –1 X 1 cm 1 ). The latter results can be interpreted as being due to a decrease in the disorder of the density of localised p states distribution [8]. Journal of Non-Crystalline Solids 299–302 (2002) 907–911 www.elsevier.com/locate/jnoncrysol * Corresponding author. E-mail address: lacerda@poly.polytechnique.fr (M. La- cerda). 0022-3093/02/$ - see front matter Ó 2002 Published by Elsevier Science B.V. PII:S0022-3093(01)00990-5