title: Photon-assisted tunneling for sub-bandgap light detection in silicon PN-doped waveguides.
abstract: We demonstrate silicon ridge waveguide photo-detectors capable of sub-bandgap light absorption and avalanche multiplication. The proposed waveguide photo-detectors contain highly doped PN junction, where a strong electric field can generate the photon-assisted tunneling current for sub-bandgap light incidence and amplify the generated photo-current by the avalanche multiplication effect. The voltage-dependent sub-bandgap absorption coefficient and multiplication gain are experimentally evaluated for various doping configurations to find optimal photo-response with low dark currents. As a result, our representative silicon waveguide photo-detector gives sub-bandgap responsivities of ~10 and ~2 A/W under the applied reverse bias voltage of -8.3 V for near-infrared wavelengths of 1.31 and 1.52 μm, respectively. The voltage-dependent frequency photo-response is also demonstrated with theoretical verification.
authors.forename: Jong-Bum
authors.initials: JB
authors.lastname: You
authors.forename: Hyeokbin
authors.initials: H
authors.lastname: Kwon
authors.forename: Jonghoon
authors.initials: J
authors.lastname: Kim
authors.forename: Hyo-Hoon
authors.initials: HH
authors.lastname: Park
authors.forename: Kyoungsik
authors.initials: K
authors.lastname: Yu