High-transparency SWIR electrode with ultrathin silver film and high-index overlay for advanced infrared applications

Achieving high optical transparency in the short-wavelength infrared (SWIR) is crucial for infrared applications. Traditional transparent electrodes based on conducting oxides and ultrathin metals exhibit poor SWIR transparency due to their high optical density. In this study, we introduce a SWIR-transparent electrode with an ultrathin silver film and high-refractive-index overlay, achieving 86% transmittance at 1300 nm with a sheet resistance of 14 Ω/□. This electrode maintains high transparency over a wide range of angles, with less than 10% deviation at 50 degrees. Integrated into silicon, these electrodes enable the first SWIR-transparent silicon hot-carrier photodetectors, demonstrating stable photocurrent and low optical interference, suitable for LiDAR, infrared imaging, and optical communication. Our approach offers a promising solution for advancing SWIR-transparent optoelectronics, contributing to the development of high-performance devices for diverse infrared applications.