A Transition Metal Dichalcogenide Tunnel FET-Based Waveguide-Integrated Photodetector Using Ge for Near-Infrared Detection

This paper presents a novel approach for the design of a waveguide-integrated photodetector that combines the advantage of atomically thin MoS ₂ tunnel FET (TFET) with infrared detection capability of Germanium (Ge). The Ge layer acting as a photogate for underlying TFET is optimized to have good optical confinement of guided mode traveling in the SOI rib waveguide. The low-power operation, effective gate control, low OFF-state current, and improved subthreshold characteristics of MoS ₂ TFET effectively enhance the detector performance for on-chip applications. Due to the high sensitivity of the TFET in the subthreshold region, an addition of the photovoltage to the gate voltage increases the band-to-band tunneling (BTBT) significantly, showing good photoresponse. The analytical and simulation results illustrate that at 1550 nm wavelength with an incident optical power intensity of 3 Wcm ⁻² , a maximum responsivity of 2700 AW ⁻¹ and an ON–OFF ratio ( $I_{ON}/I_{OFF}$ ) of 10 ⁷ is obtained. The device shows good spectral sensitivity with a low dark current.