Coherent LIPSS Propagation in Transparent Conductive Oxides (TCOs)

Transparent Conductive Oxides (TCOs) are materials with relatively high conductivity at room temperature and low optical absorptance in the visible (VIS), which makes them particularly suitable for applications in photovoltaics (energy harvesting, light detection …), information technologies (OLEDs, displays …) and transparent heaters, among others [1]. Laser processing provides a very suitable tool to modify their composition, morphology or structure to tailor their properties for specific applications [2]. The feasibility of producing strongly anisotropic surfaces by fs-laser irradiation in indium-tin-oxide (ITO) films has been demonstrated [3], [4]. Electrical and optical anisotropies were triggered by the formation of Laser Induced Periodic Surface Structures (LIPSS) [5] characterized by alternating ablated and non-ablated stripes (ridges and valleys). In addition, under some processing conditions, the compositional changes induced in the material ridges triggered a red-shift of the ITO's transparency window, which seems extremely attractive for IR-photodetectors and photovoltaics [6].