Periodicity control of laser-induced periodic nanostructures by thin deposition layer on sapphire substrate

This study concludes the possibility of controlling the period of the laser-induced periodic surface structures (LIPSSs) by deposition of a layer of different kinds of material on the processing sample. When the Pt-Pd or ZnO layers were deposited on the sapphire substrate, the period of the LIPSS formed at the sapphire surface was significantly shortened. For deposition layers thicker than 40 nm, LIPSS with periods much shorter than 330 nm, which is the period of LIPSS without a deposition layer, were formed. Some case periods of around 50 nm were obtained, which were one twentieth of the applied wavelength.