Germanium/germanium-tin heterojunction phototransistors: towards high-efficient

We report the demonstration of Si-based waveguide Ge1-xSnx photodetector (PD) at L-band (1565-1625 nm), U-band (1625-1675 nm), and 2μm light detection, optical and electrical properties are studied by using simulation models. With introduction of 4.5% Sn into Ge, the GeSn waveguide PD with evanescent coupling exhibits a high responsivity of 1.25 A/W, dark current is lower than 12 nA. This work provides a new choice for future infrared detection, beneficial to needs of broadband spectrum communication, and compatible with CMOS circuits.