The C-axis-oriented AlN thin films were fabricated on Ni-based alloy substrates using medium-frequency reactive magnetron sputtering. Hydrogen was introduced during the sputtering process to induce lattice defects, followed by high-temperature annealing to repair these defects. The crystal structures of the films were characterized by X-ray diffraction and transmission electron microscopy. The results indicate that the (0002) diffraction angle of hydrogen-doped AlN films increased linearly with rising annealing temperatures between 400 and 800 ℃. Annealing at 800 ℃ for 15 min significantly reduced the number of edge-type and screw-type dislocations in the grain regions, with a lattice spacing contraction rate of 6.64%. However, at temperatures above 800 ℃, thermal stress from the Ni-based alloy substrate caused lattice expansion, which impaired the defect-repairing effect. The (0002) diffraction angle decreased as the annealing temperature increased beyond 800 ℃. These findings demonstrate that hydrogen-doped AlN films on Ni-based alloy substrates are suitable for temperature sensing in the range of 400~800 ℃.
Li et al. (Fri,) studied this question.