A spectrally tunable plasmonic photosensor with an ultrathin semiconductor region

TL;DR

This paper presents a hybrid graphene-based plasmonic photosensor with tunable spectral response, achieving significant absorption enhancement and high photogeneration rates in the mid-IR and THz regimes, surpassing traditional metal-based sensors.

Contribution

It introduces a novel graphene-integrated photosensor with tunable SPR, enabling adjustable spectral selectivity and enhanced absorption compared to conventional metal-based designs.

Findings

Tenfold absorption enhancement over a wide incidence angle range

High photogeneration rate (~10^{37}) at resonance

Tunable spectral response via Fermi energy manipulation

Abstract

Surface plasmon resonance (SPR) has been widely utilized to improve the absorption performance in the photosensors. Graphene has emerged as a promising plasmonic material, which supports tunable SPR and shows significant flexibility over metals. In this letter, a hybrid photosensor based on the integration of periodic cross-shaped graphene arrays with an ultrathin light-absorbing semiconductor is proposed. A tenfold absorption enhancement over a large range of the incidence angle for both light polarizations as well as a considerably high photogeneration rate ($\sim10^{37}$) is demonstrated at the resonance. Compared with traditional metal-based plasmon-enhanced photosensors, the absorption enhancement here can be expediently tuned with manipulating the Fermi energy of graphene. The proposed photosensor can amplify the photoresponse to the incidence light at the selected wavelength and thus be utilized in photosensing with high efficiency and tunable spectral selectivity in the mid-infrared (mid-IR) and terahertz (THz) regime.