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–N2 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.