Modulation of optical transmittance and conductivity by the period, linewidth and height of Au square mesh electrodes.

Abstract

Metal transparent conductive electrode (TCE) with surface plasmons has been extensively studied for light absorption enhancement in solar cells and light extraction in Light-Emitting Diodes etc. But its transparent conductive properties and surface plasmons are controlled by its micromorphologies and microstructures. In this work, photoelectric coupling effects and optical transmittance modulations of period, linewidth and height of Au nanowire in square mesh electrode were investigated detailedly using a comprehensive finite-difference time domain calculation stimulation, and then Au square mesh TCEs with the 500 nm in period, 70 nm in height and linewidth ranging from 60 to 100 nm were fabricated using electron beam lithography. The measured results showed that the optical transmittance of the TCEs is about 70% in the 350-700 nm wavelength range and over 80% in the 700-1000 nm range, which accord with the theoretical simulation results. Optical transmittance is affected by reflection loss, localized surface plasmon resonances and surface plasmon polarizations (SPPs) absorption loss, concerned about geometry parameters. SPPs dip peak position exhibits a blue-shift from 844 to 812 nm and the width of peak increases with increasing the linewidth from 60 to 100 nm, The measured surface resistivity of the TCEs with the 500 nm in period, 50 nm in height and 50 nm in linewidth is about 74.5 Ω/m(2), about two times bigger than that of commercial indium tin oxide glass.