Nitrogenated carbon films deposited using filtered cathodic are

Nitrogenated carbon films were deposited on various substrates using filter ed cathodic are. Non-uniformity of the film thickness was less than 5% over a 15 cm diameter area. Mechanical, optical (refraction index, extinction c oefficient versus wavelength) and electrical properties were investigated a s a function of nitrogen flow rate. Deposited coatings demonstrated high ha rdness of 40-65 Cpa, Young's modulus 200-285 Cpa, excellent elastic recover y, high critical pressure for scratch formation, and surface smoothness. Wh ile the hardness showed a relatively small decrease with nitrogen flow incr ease, the stress decrease was more significant (8-3.8 GPa). Extremely low w ear rates were observed, even at high contact pressures, and no substantial debris was detected indicating that carbon is oxidized during wear. Clear correlation was found between transparency, electrical resistivity and stre ss of the films. Transparency and resistivity showed a significant rise wit h an increase of stress. An explanation of the film properties is based on the assumption that the basic characteristics of the deposited films were d etermined by the relative proportion of two three dimensional complementary type of bonds, the tetrahedral sp(3) bonds leading to stiff networks, and the trigonal sp(2) arrangments close to fullerene-like, or nanotube-like, s tructures. (C) 2000 Elsevier Science S.A. All rights reserved.