Wafer-level fabrication and optical characterization of nanoscale patterned sapphire substrates

► Wafer-level nanostructures were fabricated atop double-side sapphire substrates. ► The fabrication method was used natural lithography and dry-etching method. ► The optical characterization of nanostructures exhibits a high transmittance. ► Increasing transmittance was over broadband spectra with wide incident angles.