Optimizing geometry and metal-dependent performance of Si-based Schottky plasmonic photodetectors

Abstract

In this study, different Schottky photodetectors with a plasmonic assist which receives Near-infrared (NIR) light at room temperature were demonstrated. We achieved remarkable detection over a wide range of wavelengths through a comparative study of Schottky plasmonic photodetectors employing Au, Ti, Mo, and Cr as a Schottky metal, a diffusion barrier, an adhesion promoter, and to suppress the formation of intermetallic compounds and plasmonic resonance shifts. The device structure is determined by extensive experimental and modeling results, ensuring a wavelength-specific plasmonic photodetection and a near one-to-one correspondence between incident angles and wavelengths within the NIR region. The combination of different metals in the plasmonic structure efficiently broadened the SPR response, due to the variation of junction barrier height and enhanced interface properties. It exhibited exceptional photocurrent response under room temperature and zero biasing conditions, characterized by high linearity and sensitivity. Light acquisition for longer NIR wavelengths became possible, and applicable in gas sensing, particularly within the vibrational absorption bands of alkane groups. These findings provide valuable design guidelines for optimizing device structures and insights into their application for various scenarios.