Formation of regular arrays of silicon microspikes by femtosecond laser irradiation through a mask

We report fabrication of regular arrays of silicon microspikes by femtosecond laser irradiation of a silicon wafer covered with a periodic mask. Without a mask, microspikes form, but they are less ordered. We believe that the mask imposes order by diffracting the laser beam and providing boundary conditions for capillary waves in the laser-melted silicon. (C) 2003 American Institute of Physics.