title: Vertical p-i-n germanium photodetector with high external responsivity integrated with large core Si waveguides.
abstract: We report a vertical p-i-n thin-film germanium photodetector integrated on 3microm thick large core silicon-on-insulator (SOI) waveguides. The device demonstrates very high external responsivity due to the low fiber coupling loss to the large core waveguides. The germanium width and thickness are carefully designed to achieve high responsivity yet retain high-speed performance. Even with fiber coupling loss included, the device has demonstrated greater than 0.7A/W external responsivity at 1550nm for TM polarization and 0.5A/W for TE polarization. A low dark current of 0.2microA at -0.5V bias is reported. 3dB bandwidths of 12GHz and 8.3GHz at -2.5V bias are also reported for 100microm and 200microm long devices, respectively. The device can cover the communication wavelength spectrum up to 1620nm with a relatively flat responsivity of >0.5A/W. Further studies suggest that with a modified design the device is capable of achieving 1A/W external responsivity for both TE and TM polarizations and greater than 30GHz bandwidth.
authors.affiliation: Kotura Inc., 2630 Corporate Place, Monterey Park, CA 91754, USA. nfeng@kotura.com
authors.forename: Ning-Ning
authors.initials: NN
authors.lastname: Feng
authors.forename: Po
authors.initials: P
authors.lastname: Dong
authors.forename: Dawei
authors.initials: D
authors.lastname: Zheng
authors.forename: Shirong
authors.initials: S
authors.lastname: Liao
authors.forename: Hong
authors.initials: H
authors.lastname: Liang
authors.forename: Roshanak
authors.initials: R
authors.lastname: Shafiiha
authors.forename: Dazeng
authors.initials: D
authors.lastname: Feng
authors.forename: Guoliang
authors.initials: G
authors.lastname: Li
authors.forename: John E
authors.initials: JE
authors.lastname: Cunningham
authors.forename: Ashok V
authors.initials: AV
authors.lastname: Krishnamoorthy
authors.forename: Mehdi
authors.initials: M
authors.lastname: Asghari
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D055096:Optical Devices; D010783:Photometry / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry*; D018511:Systems Integration
chemical_list: D012825:Silicon