2.3. Samples Topography and Morphological Analyses

A Tencor Alpha-Step^® 500 stylus profilometer (KLA—Milpitas, CA, USA), with a nominal vertical resolution of 0.1 nm, was used to measure step height and surface roughness (defined as the root mean square of the height deviations averaged along the scan length, Rq) of the investigated samples. An X-Y stage enables the mapping of the 2D step height and surface roughness measurements. We used a stylus scan speed of 200 μm/s to obtain the whole profile, and 10 μm/s for the lateral profile and for evaluating the surface roughness. Scanning electron microscopy (SEM) images were recorded using a Zeiss (Oberkochen, Germany) Merlin^® FE-SEM equipped with a GEMINI II electromagnetic/electrostatic objective lens system, operating at 20 kV.