Spin-on-dopant phosphorus diffusion in germanium thin films for near-infrared detectors

Authors

  • V. Sorianello,

    1. NooEL-Nonlinear Optics and OptoElectronics Lab., University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
    2. CNIT-Laboratory of Photonic Networks, Via Moruzzi 1, 56124 Pisa, Italy
    Search for more papers by this author
  • A. De Iacovo,

    1. NooEL-Nonlinear Optics and OptoElectronics Lab., University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
    Search for more papers by this author
  • L. Colace,

    Corresponding author
    1. NooEL-Nonlinear Optics and OptoElectronics Lab., University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
    • NooEL-Nonlinear Optics and OptoElectronics Lab., University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy===

    Search for more papers by this author
  • A. Fabbri,

    1. Surface Analysis Laboratory, Physics Department, University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
    Search for more papers by this author
  • L. Tortora,

    1. Surface Analysis Laboratory, Physics Department, University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
    2. Department of Industrial Engineering, University Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
    Search for more papers by this author
  • G. Assanto

    1. NooEL-Nonlinear Optics and OptoElectronics Lab., University Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
    Search for more papers by this author

Abstract

Threading dislocations in germanium thin films on silicon introduce acceptor states in the germanium bandgap close to the valence band. Thus, highly defected germanium thin films spontaneously exhibit a p-type behavior. Here we report on spin-on-dopant diffusion of phosphorus in thermally evaporated, highly defected germanium thin films. We demonstrate effective compensation of the acceptor states associated to dislocations by means of post-growth doping.

We discuss phosphorus diffusion in these highly defected films and pinpoint the benefits of spin-on-doping by realizing and testing near-infrared photodiodes in evaporated Ge on Si, achieving high responsivities which compare well with those of state-of-the-art Ge p-i-n photodiodes. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ancillary