Controlling spontaneous surface structuring of azobenzene-containing polymers for large-scale nano-lithography of functional substrates

In this work, we investigate the effect of illumination parameters which is light polarization, wavelength, and beam focalization, on the large-scale patterning of the surface of azobenzene-containing polymer films by means of spontaneous surface structuring. This is a phenomenon due to the interference at the sample surface between different light modes originated by scattering from the primary illuminating beam. In particular, the surface patterning in regions of a few squared millimeters with a spatial resolution down to 180nm is achieved by means of a single beam illumination. The realized topographical structures are both preferentially oriented gratings and isotropically distributed topographical protrusions (dots), with sub-wavelength features.