*2.2. Surface Analysis*

The generated surface structures were analyzed using atomic force microscopy (XE-150, Park Systems, Suwon, Korea) and scanning electron microscopy (EVO MA10,Carl Zeiss Microscopy GmbH, Jena, Germany). The AFM measurements were used to obtain the 3D surface topology of the different structures in order to determine the depth of the structures. The AFM was operated in non-contact mode using a cantilever with high aspect ratio (>5:1) silicon tip (NANOSENSORS AR5-NCHR, NanoWorld AG, Neuchatel, Switzerland). Images with 512 × 512 pixels were recorded at a scan rate of 0.2 lines per second and a scan size of 10 × 10 μm. The SEM images with 1024 × 768 pixels were taken at a high voltage of 18–20 kV, a filament current of 2.39–2.44 A, and a probe current of 3–20 pA. The working distance was 5–8 mm and the minimum pixel size 5.86 nm.
