42 GHz pin Germanium photodetector integrated in a silicon-on-insulator waveguide

TLDR

A compact pin Ge photodetector is integrated into a sub‑micron SOI rib waveguide, with a 15 µm length using butt coupling to fully absorb 1.55 µm light, and fabricated with a CMOS‑compatible process. The device achieves a –3 dB bandwidth of 42 GHz at 4 V reverse bias, a responsivity of 1 A/W at 1.55 µm, a low dark current density of 60 mA/cm², and 1 A/W responsivity at 1.52 µm under –0.5 V bias.

Abstract

A compact pin Ge photodetector is integrated in submicron SOI rib waveguide. The detector length is reduced down to 15 microm using butt coupling configuration which is sufficient to totally absorb light at the wavelength of 1.55 microm. A -3 dB bandwidth of 42 GHz has been measured at a 4V reverse bias with a responsivity as high as 1 A/W at the wavelength of 1.55 microm and a low dark current density of 60 mA/cm(2). At a wavelength of 1.52 microm, a responsivity of 1 A/W is obtained under -0.5 V bias. The process is fully compatible with CMOS technology.