Boosting external quantum efficiency of a WSe2 photodetector across visible and NIR spectra through harnessing plasmonic hot electrons

Abstract

The layered two-dimensional material tungsten diselenide (WSe2) has triggered tremendous interests in the field of optoelectronic devices due to its exceptional carrier transport property. Nevertheless, the limited absorption of WSe2 in the near infrared (NIR) band poses a challenge for the application of WSe2 photodetectors in night vision, telecommunication, etc. Herein, the enhanced performance of the WSe2 photodetector is demonstrated through the incorporation of titanium nitride nanoparticles (TiN NPs), complemented by an atomically-thick Al2O3 layer that aids in suppressing the dark current. It is demonstrated that TiN NPs can dramatically enhance the absorption of light in the proposed WSe2 photodetector in the NIR regime. This enhancement boosts photocurrent responses through the generation of plasmonic hot electrons, leading to external quantum efficiency (EQE) enhancement factors of 379.66% at 850 nm and 178.47% at 1550 nm. This work presents, for the first time, to our knowledge, that the WSe2 photodetector is capable of detecting broadband light spanning from ultraviolet to the telecommunication range, all achieved without the reliance on additional semiconductor materials. This achievement opens avenues for the advancement of cost-effective NIR photodetectors.