Study of the formation of a microrelief on ZnSe- and CdSe-crystal surfaces ablated by excimer KrF-laser radiaton

One-dimensional gratings with a period of 0.5 – 2.3 μm are formed on the surfaces of CdSe and ZnSe crystals ablated by two interfering radiation beams of a nanosecond excimer KrF laser. Investigated are the dependences of the shape and depth of gratings on the energy density under irradiation by a single pulse, and on the number of pulses at a given energy density. The maximum grating depth is estimated as ~0.57 of the period. By forming a one-dimensional grating with a period of 1.5 μm and a depth of 0.53 μm on the CdSe-crystal surface, this surface becomes antireflective at a wavelength of 4 μm. The surface reflectivity is reduced by 88%. A possibility of forming two-dimensional gratings having periods of 1 and 1.5 μm is demonstrated.