Monitoring the structural and chemical properties of CN_x thin films during in situ annealing in a TEM

¹ CEMES/CNRS, 29 rue Jeanne Marvig, BP 4347, 31055 Toulouse, France
² Thin Film Physics Division, Department of Physics, Linköping University, 58183 Linköping, Sweden
³ Laboratoire de Physique des Solides (URA 002), Université de Paris-Sud, Bât. 510, 91405 Orsay, France and Laboratoire Aimé Cotton (UPR 3321), Campus d'Orsay, Bât. 505, 91405 Orsay, France

Corresponding author: Stefano.Grillo@univ-perp.fr

Received: 9 May 2000
Revised: 12 July 2000
Accepted: 9 November 2000
Published online: 15 February 2001

Abstract

Carbon nitride films synthesised by magnetron sputtering at different substrate temperatures have been studied using electron energy loss spectroscopy (EELS) during annealing performed in situ in a transmission electron microscope (TEM). The proportion of sp² hybridised carbon slightly decreases initially during heating, presumably because of the removal of defects in the structure, whilst it increases at higher temperatures when graphitisation tends to take place, as confirmed by high resolution electron microscopy (HREM). Substantial amounts of nitrogen (up to ~ 80% ) are removed following annealing at 1000 °C. A corresponding decrease in the pre-peak of the nitrogen spectra suggests that pyridine-like N is released by annealing. As this peak component decreases, a second peak, of weaker intensity, is becoming apparent in the EELS spectra when the films are heated at temperatures above approximately 700 °C. The possibility has been suggested that this corresponds to N substituted for C in a graphitic structure, with possibly also some N₂ contributing to the peak.