Influence of passivation layer on plasmonic infrared filter for image sensors

We report the influence of a cover passivation layer on a plasmonic infrared filter for image sensors and the proper dimensions of a plasmonic dual-band infrared filter. We simulated the spectral variation in light transmission using a few important parameters: the metal thickness, the aperture pitch, the aperture diameter, and three different conditions of the structure's cover passivation layer. For this implementation, we used a commercial computer simulation tool utilizing the finite-difference time-domain method. Moreover, we explain briefly the mechanism of an active-type dual-band infrared image sensor and also a large-area multi-touch display using an optical camera module into which the plasmonic dual-band infrared filter is integrated to decrease touch recognition errors. Based on the results of the computer simulation, we identified two necessary conditions for the plasmonic dual infrared band pass filter. We expect that a plasmonic infrared band pass filter could be realized using a simple insulator/metal/insulator structure.