Forming ITO/Ag Hole-Array/ITO Multilayers for Near Infrared Transparent Conducting Electrodes and Filters

Abstract

Ag hole-array samples (400 and 500 nm in period) were used to realize near infrared (NIR) transparent electrodes and filters for NIR optical devices. The opto-electrical properties of the ITO/Ag hole-array/ITO multilayer (ITO/hole/ITO sample) were investigated as functions of the hole period and ITO layer thickness. For comparison, the opto-electrical properties of ITO and ITO/Ag film/ITO samples were also examined. The ITO/hole/ITO sample exhibited characteristic features: (i) The hole-array samples revealed small dips below 775 nm and large minima in the 800 - 1200 nm wavelength region, above which the transmittance reached global maxima; ii) The overall transmittances were red-shifted with the hole period and ITO thickness. The transmittance of the ITO/hole/ITO sample (300 nm in diameter), ITO/Ag film/ITO, and ITO samples was shown to be 83.0%, 16.8% and 96.4% at 1421nm, respectively. The 10 nm and 70 nm-thick ITO multilayer samples had maximum transmittances of 82.1% at 1,082 nm and 80.4% at 1337 nm, respectively. Finite-difference time-domain (FDTD) simulations were performed to describe the transmittance behavior. On the basis of the FDTD simulations, the transmittance minima and enhanced transmittance of the ITO/hole/ITO samples are ascribed to surface plasmon polariton (SPP) resonance effect. (C) 2019 The Electrochemical Society.