Ion-induced pattern formation on indium tin oxide for alignment of liquid crystals

Indium tin oxide (ITO) is broadly used as a transparent conducting material for electrodes in optoelectronic devices. Irradiation of ITO with low energy ions can result in the formation of periodic surface nanopatterns which can serve as an alternative for the polymer alignment layer in liquid crystal devices. We investigated the formation of the ion-induced surface nanopatterns on ITO with focus on the influence of the crystalline structure of the material. We find that the crystallinity plays a crucial role in the pattern formation, with no pattern developing on an amorphous ITO surface. We discuss these findings in the context of the state-of-the-art theory for ion-induced patterning. We show that the ion-induced pattern plays a critical role in the liquid crystal alignment on ITO surfaces.