Fill factor controlled nanoimprinted ZnO nanowires based on atomic layer deposition

Enhanced diffraction by sub-wavelength nanostructures to convert incident electromagnetic radiation into waveguide modes has applications in anti-reflective coatings for optoelectronic devices. We propose a metal oxide (ZnO) nanowire grid polarizer as such a nanostructure, fabricated by ultraviolet nanoimprint lithography and whose fill factor (FF) is controlled by atomic layer deposition. Using finite difference time domain simulations, we investigated the polarization-dependent optical transmittance of the structures and calculated the polarizing efficiency. Optical profiles such as electric and magnetic field intensity and current density distributions of specific FF nanopatterns were determined for the transverse magnetic and transverse electric modes. The effects of geometrical parameters including the wire-grid period, fill ratio, and spacing between the wire-grid layers on diffraction wavelength were characterized. Respective FF-controlled ZnO nanowire structures were fabricated and their experimental optical transmittances were measured for nanowire grid polarizer applications.