Structural and electrical properties of sputtered titanium boronitride films

Titanium boronitride (TiBN) films are deposited on steel and glass substrates by DC magnetron sputtering of a TiB2 target in various Ar-N-2 mixtures. In this report the electrical properties of TiBN films are investigated in connection with their structure. At low nitrogen flow rate, the films are nanocrystallized in a TiB2-like structure. On the other hand at high nitrogen flow rate, TiBN films contain nanocrystals of TiN probably embedded in a boron nitride amorphous matrix. The electrical resistivity of TiBN films increases continuously with the nitrogen flow rate. The thermal behaviour of the electrical resistance shows that coatings with a TiB2-like structure have a positive temperature coefficient of resistance, whereas samples obtained under high nitrogen flow rate exhibit a negative one. These results are discussed together with those obtained from high-resolution photoemission spectroscopy, which gives evidence to the metallic character for all deposits. (C) 2001 Elsevier Science B.V. All rights reserved.