Broadband and high-responsivity SiC-based hot-electron photodetector driven by TiN/SiN core-cap disk array

Abstract

Silicon carbide (SiC) photodetectors are highly valued for their exceptional stability in harsh environments. However, their wide bandgap (∼3.3 eV) fundamentally constrains the spectral response, limiting detection primarily to the ultraviolet regime. To overcome this inherent limitation, we present a SiC-based hot-electron photodetector (HEPD) incorporating a plasmonic electrode featuring a TiN/SiN core-cap disk array. By leveraging the plasmon-induced hot-electron effect, this device achieves exceptionally broad detection capability ranging from 400 to 2100 nm. The detector exhibits a peak responsivity of 0.473 mA/W at 720 nm, representing a 435% enhancement compared to the planar device. A substantial improvement is maintained across the entire 400–2100 nm spectrum, with an average responsivity increase of 374%. This superior performance in spectral coverage and response intensity completely surpasses its Au- and Ag-core counterparts. The peak responsivities of both Au- and Ag-core devices are merely 0.009 and 0.06 mA/W, respectively, which are two orders of magnitude lower. Additionally, by engineering the effective Schottky barrier height, the peak responsivity of the proposed device can be further elevated to 2.33 mA/W, with the detection spectrum broadened to 2600 nm. This work provides a critical theoretical foundation for developing high-performance, broadband SiC photodetectors, paving the way for their application in a wider range of optical sensing scenarios.