Grating-assisted hot-electron photodetectors for S- and C-band telecommunication

Abstract

There has been an increasing demand for cryogen-free, cost-effective, and broadband infrared photodetectors in optic fiber communication systems. Here, differing from costly and spectra-limited InGaAs photodetectors, we present a design of hot-electron photodetectors (HE PDs) with attributes of room-temperature operation and strong optical absorption over S and C bands (from 1460 nm to 1565 nm). The designed HE PD consists of a metal-semiconductor-metal hot-electron stack integrated with a front grating. Optical simulations reveal that mode hybridizations between Fabry-Pérot resonance and grating-induced surface plasmon excitation lead to high absorption efficiencies (≥ 0.9) covering S and C bands. Probability-based electrical calculations clarify that device responsivity is mainly determined by working wavelength on the premise of broadband strong absorption. Moreover, through comparison studies between the grating-assisted HE PD and purely planar microcavity system that serves as a reference, we highlight the design superiorities in average absorption and average responsivity with optimized values of 0.97 and 0.73 mA/W, respectively.