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

TiNx 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 TiNx 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 TiNx 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 TiNx films. As the N2 flow rate rose from 1  to 2 sccm, the resistivity and emissivity of the TiNx films went up, and then dropped with the N2 flow rate further increase.