Influence of the nitrogen flow rate on the infrared emissivity of TiN_x films

TiN_x films were deposited on glass substrates by DC reactive magnetron sputtering technique. The influence of N₂ flow rates (1, 2, 4, and 20 sccm) on the structure, resistivity, and infrared emissivity of TiN_x films was studied. The XRD patterns showed that the films deposited at 1, 2, and 4 sccm were composed of TiN phase with a faced-centered cubic crystal structure. As the N₂ flow rate rose from 1 to 4 sccm, the preferred orientation of the films altered from (1 1 1) to (2 0 0) plane. Upon further increased to 20 sccm, the XRD peaks were almost indiscernible. The XPS analysis revealed that the TiN_x films were nitrogen deficient, and titanium oxy-nitride and TiO₂ phase formed in the films. The N/Ti stoichiometry ratio increased from 0.69 to 0.98 with the N₂ flow rate rise. The resistivity variation was consistent with the infrared emissivity in the band of 8–14 μm of TiN_x films. As the N₂ flow rate rose from 1 to 2 sccm, the resistivity and emissivity of the TiN_x films went up, and then dropped with the N₂ flow rate further increase.