Photodetection in Hybrid Single-Layer Graphene/Fully Coherent Germanium Island Nanostructures Selectively Grown on Silicon Nanotip Patterns

Research output: Contribution to journalResearch articleContributedpeer-review


  • Gang Niu - , Xi An Jiao Tong Univ, Xi'an Jiaotong University, Int Ctr Dielect Res (Author)
  • Giovanni Capellini - , Roma Tre University (Author)
  • Grzegorz Lupina - , Innovations for High Performance Microelectronics (Author)
  • Tore Niermann - , Technical University of Berlin (Author)
  • Marco Salvalaglio - , University of Milan - Bicocca (Author)
  • Anna Marzegalli - , University of Milan - Bicocca (Author)
  • Markus Andreas Schubert - , Innovations for High Performance Microelectronics (Author)
  • Peter Zaumseil - , Innovations for High Performance Microelectronics (Author)
  • Hans-Michael Krause - , Innovations for High Performance Microelectronics (Author)
  • Oliver Skibitzki - , Innovations for High Performance Microelectronics (Author)
  • Michael Lehmann - , Technical University of Berlin (Author)
  • Francesco Montalenti - , University of Milan - Bicocca (Author)
  • Ya-Hong Xie - , University of California at Los Angeles (Author)
  • Thomas Schroeder - , Brandenburg University of Technology (Author)


Dislocation networks are one of the most principle sources deteriorating the performances of devices based on lattice-mismatched heteroepitaxial systems. We demonstrate here a technique enabling fully coherent germanium (Ge) islands selectively grown on nanotippatterned Si(001) substrates. The silicon (Si)-tip-patterned substrate, fabricated by complementary metal oxide semiconductor compatible nanotechnology, features similar to 50-nm-wide Si areas emerging from a SiO2 matrix and arranged in an ordered lattice. Molecular beam epitaxy growths result in Ge nanoislands with high selectivity and having homogeneous shape and size. The similar to 850 degrees C growth temperature required for ensuring selective growth has been shown to lead to the formation of Ge islands of high crystalline quality without extensive Si intermixing (with 91 atom % Ge). Nanotip-patterned wafers result in geometric, kinetic-diffusion-barrier intermixing hindrance, confining the major intermixing to the pedestal region of Ge islands, where kinetic diffusion barriers are, however, high. Theoretical calculations suggest that the thin Si/Ge layer at the interface plays, nevertheless, a significant role in realizing our fully coherent Ge nanoislands free from extended defects especially dislocations. Single-layer graphene/Ge/Si-tip Schottky junctions were fabricated, and thanks to the absence of extended defects in Ge islands, they demonstrate high-performance photodetection characteristics with responsivity of similar to 45 mA W-1 and an I-on/I-off ratio of similar to 10(3).


Original languageEnglish
Pages (from-to)2017-2026
Number of pages10
JournalACS applied materials & interfaces
Issue number3
Publication statusPublished - 27 Jan 2016
Externally publishedYes

External IDs

Scopus 84955585236



  • germanium, selective epitaxy, elastic relaxation, graphene, photodetection, EPITAXIAL-GROWTH, GE ISLANDS, SI, DIFFUSION, OXIDATION, SI(001), NANOHETEROEPITAXY, HETEROJUNCTION, HETEROEPITAXY, EVOLUTION