Fabrication and measurement of large-area sub-wavelength structures with broadband and wide-angle antireflection effect

Abstract

In this paper, large-area two-dimensional sub-wavelength structures (SWS) on Si substrates are fabricated by combining interference lithography and reactive ion etching. The average reflectance of the SWS samples is less than 2.87% with broadband operation from 250 to 1200 nm. It also shows good uniformity over the whole patterned area by measuring 16 divided SWS areas. The reflectance variations with different incident angles are measured by our varied-angle reflectometer and the reflectance is lower than 5% for the incident angles smaller than 50° over the broadband region.