Study on the infrared emissivity of nonstoichiometric titanium chromium nitride films

Nonstoichiometric titanium chromium nitride (TiCrN) thin films with different nitrogen stoichiometric ratio were prepared by reactive magnetron co-sputtering. The nitrogen stoichiometric ratio was adjusted by change in the sputtering power. The phase compositions, morphology, adhesion force, resistivity and infrared emissivity were studied systematically. The results show that the adhesion force increased with increasing of the nitrogen stoichiometric ratio. The crystallinity was poor and the grain size was small when the nitrogen stoichiometric ratio was 0.35, leading to a great increase of resistivity and infrared emissivity of TiCrN film. When the nitrogen stoichiometric ratio was 0.44, the films crystallized and severe deformation of TiCrN crystal structure led to high resistivity and infrared emissivity. After the nitrogen stoichiometric ratio reached 0.58, serious deformation of TiCrN crystal weakened, and the combined effect of crystal deformation and carrier density caused the variation of the infrared emissivity. The infrared emissivity value of TiCrN film with nitrogen stoichiometric ratio of 0.58 was almost close to the value with nitrogen stoichiometric ratio of 0.81. Reduction of nitrogen stoichiometric ratio appropriately or decrease of crystal deformation in nonstoichiometric crystal TiCrN films was beneficial to reduce the infrared emissivity. The infrared emissivity of TiCrN films could be reduced to about 0.3.