Effects of polarization direction on removal characteristics of silver nanowire transparent conductive film by ultrashort pulsed laser

摘要

Silver nanowire transparent conductive film is expected as a new material of transparent electrode, because of its superior flexibility and electrical conductivity with transparency at visible wavelength. It is essential to form insulation areas on the silver nanowire transparent conductive film in electronic circuit. Laser beam processing has been widely used for this application, since high efficiency and high quality removal is possible without mechanical contact. On the other hand, laser beam is an electromagnetic wave, and it has unique characteristics such as refraction and polarization. These characteristics have a great influence on laser-material interaction, especially in nanosize materials. However, laser processing characteristics and its mechanism have not yet been clarified. Therefore, polarization indicated by electric and magnetic fields was discussed in this study, and effects of polarization direction on removal characteristics of silver nanowire transparent conductive film by ultrashort pulsed laser with linear polarization were experimentally and numerically investigated. Removal phenomena of silver nanowire transparent conductive film by linear polarization was different from that by circular polarization. Silver nanowires arranged in the parallel direction to polarization plane were preferentially removed. In the case of crossed two silver nanowires, electromagnetic field analysis revealed that electric field intensity of silver nanowire arranged in parallel direction to polarization plane is higher than that in perpendicular direction to polarization. Therefore, silver nanowires were selectively removed depending on the polarization plane of laser beam. Electric field intensities of silver nanowire arranged in not only parallel but also perpendicular direction to polarization plane were enhanced at intersection of silver nanowires, and holes as removal marks become remarkably large at intersections of silver nanowires.