Indium tin oxide (ITO) films have been widely used in optoelectronic devices, such as solar cells, organic light emitting diodes, liquid crystal devices and so on. The simple and efficient laser annealing technologies have been employed to achieve the desired structure and properties of the films for practical applications. We focus on an 1064nm quasi-CW laser annealing, which is maybe an alternative low-cost choice compared with the current excimer and fs laser annealing. Effects of 1064nm quasi-CW laser annealing on the optical performance, electrical property and chemical composition of the ITO film were investigated in detail in this paper. It was found that the ITO film surface appeared discoloration annealed by 2000 W/cm2. Experimental results showed the transmittance of the above annealed ITO film at near-infrared band was improved obviously and the electrical sheet resistance was increased slightly compared with that of the unannealed film. The improvement of the transmission at 1064nm of the annealed film come from the reduction of absorption. The XPS analysis results showed a modification of rations of oxygen and Sn2+ after laser annealing, indicating the reduction of oxygen vacancy and free electrons, were responsible for the optoelectrical property modification of ITO films. However, when the higher annealed laser power density was utilized, the ITO film surface occurred laser-induced cracks. The annealing mechanism was discussed.
The damage characteristics of the indium-tin-oxide (ITO) layer and the polyimide (PI) layer, which are two constituent components of a LCD, induced by a high-peak-power laser and a high-average-power laser are investigated. The PI alignment layer is pinned on the ITO film to imitate the structure of the LCD as much as possible in our study. Under the irradiation of the high-peak-power laser, the damage process of the PI/ITO/SUB sample involves thermally induced plastic deformation, followed by cooling when the irradiation fluence is near the LIDT, and rupture when the irradiation fluence is higher. High-average-power laser irradiation results in damaged morphologies of the bulge for the PI/ITO/SUB sample. The temperature distributions induced by the pulsed laser and the high-repetition-rate laser are investigated. The damage is attributed to the intrinsic heat absorption of the ITO films. Under the irritation of the high-peak-power laser, the temperature rises rapidly to a high degree at very short time because of the instant strong absorption in ITO layer, and resulted in vaporization of ITO layer consequently. Subsequently, the vaporized ITO breaks through the surface PI and develops the visible damage. However, under the irritation of high-average-power laser, ITO layer absorbs laser energy, resulting in a slow temperature rise and a small temperature gradient.
Quasi-CW laser damage process of indium tin oxide (ITO) thin film was investigated. The ITO film with thickness of 300 nm was deposited on fused silica substrate by magnetron sputtering. Experiments were conducted on quasi-CW laser with wavelength of 1064 nm, and the test was executed in single shot test with radiation time of 60 s. The damage morphologies were observed via optical microscope and scanning electron microscope (SEM). The apparent damage started with change in color which the morphologies were visible to the naked eyes. With the power density higher than the laser induced damage threshold (LIDT), there were cracks in the center of the damage site. The temperature distribution of the ITO thin film was investigated based on the heat equation.
Quasi-CW laser damage behaviors of indium tin oxide (ITO) single-layer and polyimide (PI) on ITO bi-layer were investigated. The ITO single-layer with thickness of 25nm was deposited on fused silica substrate by magnetron sputtering, and the PI/ITO bi-layer was prepared by spin coating 80nm PI film on the 25nm ITO single-layer. Single-shot, with radiation time of 120 seconds, laser induced damage threshold (LIDT) of the samples were determined according to ISO 21254. The damage morphologies were mapped by optical profiler. It showed interesting phenomena that the PI top layer increased LIDT of the sample. The typical damage morphologies were blisters, and the height of the blisters increased as the laser power density increases. The formation and evolution of the blisters were analyzed.