A dual-band graphene/silicon nanowire array heterojunction photodetector induced by leaky mode resonances

Dual-band photodetectors (DBPDs) have played an essential role in multispectral information monitoring, including in civil and military areas. Traditional multispectral detectors usually consist of multiple monochromatic detectors or use filters to achieve specific wavelength detection. Needless to say, the additional detectors and optical components usually increase the physical volume leading to high costs, which are not conducive to commercial promotion. In this work, we fabricate a DBPD by using a silicon nanowire array (Si NW) with a diameter of 140 nm. According to COMSOL simulations, leaky mode resonances (LMRs) (HE11, HE12) in Si NWs with a diameter from 120 nm to 150 nm lead to a dual-band absorption phenomenon. The device analysis shows two peak responsivities which are 353 mu A W-1 under 430 nm illumination and 487 mu A W-1 under 660 nm illumination, respectively, at zero bias voltage. This result coincides well with the simulations and provides practical support for the silicon-based wavelength-selective spectral detection device.