Residual Stress Analysis of Aluminum-doped Zinc Oxide Films under Laser-Induced Recovery Process

In this study, a low-temperature annealing technique using an ultraviolet laser was proposed for inducing the crystallization of transparent conductive aluminum-doped zinc oxide (AZO) films. The technique was used in conjunction with a galvanometer scanner to adjust the laser energy density and scanning speed, thereby inducing the amorphous crystallization of thin films. X-ray diffraction was used to analyze the structural properties of annealed thin films. Analysis with different galvanometer scanning speed during annealing and laser pulse repetition rates during annealing revealed that the two diffraction peaks (i.e., the (002) and (103) peaks) of the zinc oxide thin films became more noticeable as the laser pulse repetition rate increased. When the galvanometer scanning speed during annealing was set to 400 mm/s and 600 mm/s, the full width at half of the maximum (FWHM) of the AZO thin films decreased while the annealing frequency increased. By contrast, when the annealing speed was 800 mm/s, increasing the annealing frequency caused the FWHM to decrease and then increase. An analysis of the residual stress of the annealed thin film confirmed that when the annealing speed was reduced from 800 mm/s to 400 mm/s, increases in laser pulse repetition rate resulted in increased residual stress.