Journal of Materials Science

, Volume 46, Issue 17, pp 5737–5742 | Cite as

Photovoltaic properties and photoconductivity in multilayer Ge/Si heterostructures with Ge nanoislands

  • S. V. Kondratenko
  • O. V. Vakulenko
  • Yu. N. Kozyrev
  • M. Yu. RubezhanskaEmail author
  • A. G. Naumovets
  • A. S. Nikolenko
  • V. S. Lysenko
  • V. V. Strelchuk
  • C. Teichert


Interband optical transitions in multilayer heterostructures with SiGe nanoislands were investigated using photocurrent spectroscopy and photo-emf. The n-p heterostructures containing Ge nanoislands in the area of the potential barrier were prepared by molecular-beam epitaxy at the temperature about 500 °C. It was shown that electron transitions from the ground state of the valence band in a nanoislands to the conduction band of Si surrounding made the main contribution into the vertical photo-emf in the range 0.75–1.05 eV, which is below the interband absorption edge of Si. The lateral photoconductivity observed in the range 0.63–0.8 eV at 77 K can be attributed to indirect interband transitions from the ground state of a nanoisland to L-state of the conduction band of a nanoisland. Analysis of Raman scattering spectra revealed that the Ge composition x in a nanoisland is about 0.87, while elastic deformation value amounts to εxx = −0.016. The calculated energies of interband transitions from the ground state of a nanoisland to the conduction band of Si surrounding (0.63 eV) and to L-state of the conduction band of a nanoisland (0.81 eV) fit the experimental data with a rather good accuracy.


Interband Transition Heavy Hole Band Discontinuity Valence Band State Interband Optical Transition 



The research was implemented within the bilateral ÖAD Project UA No 2009/08 and supported by the program of fundamental research of the National Academy of Sciences of Ukraine “Nanostructured systems, nanomaterials, nanotechnologies” through the Project No9/07 and by the Ministry of Education and Science of Ukraine through Project NoM/34-09.


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • S. V. Kondratenko
    • 1
  • O. V. Vakulenko
    • 1
  • Yu. N. Kozyrev
    • 2
  • M. Yu. Rubezhanska
    • 2
    Email author
  • A. G. Naumovets
    • 3
  • A. S. Nikolenko
    • 4
  • V. S. Lysenko
    • 4
  • V. V. Strelchuk
    • 4
  • C. Teichert
    • 5
  1. 1.Physics DepartmentKiev National Taras Shevchenko UniversityKievUkraine
  2. 2.O.O. Chuiko Institute of Surface ChemistryKievUkraine
  3. 3.Institute of PhysicsKievUkraine
  4. 4.Institute of Semiconductor PhysicsKievUkraine
  5. 5.Institute of Physics, Montanuniversitaet LeobenLeobenAustria

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