Optical constants and interband transitions of Ge1-xSn x alloys (x<0.2) grown on Si by UHV-CVD

Candi S. Cook, Stefan Zollner, Matthew R. Bauer, Pavan Aella, John Kouvetakis, Jose Menendez

Research output: Contribution to journalConference articlepeer-review

33 Scopus citations


The development of manufacturable direct band gap materials on Si is crucial for optoelectronic devices integrated with silicon circuits. Ge-Sn alloys with varying metastable compositions ranging from 2 to 20% were grown by UHV-CVD using a deuterium-stabilized Sn hydride with digermane. We use deep ultraviolet spectroscopic ellipsometry (0.74 to 6.6 eV) to determine the optical properties of this new class of Si-based infrared semiconductors in the Ge 1-xSnx system. Optical analysis of the energy-derivatives in comparison with analytical lineshapes shows that the E1 and E 2 interband transition energies decrease significantly with increasing Sn content. Tunability of these high-energy gaps shows promise for a direct E0 band gap in this materials system.

Original languageEnglish (US)
Pages (from-to)217-221
Number of pages5
JournalThin Solid Films
StatePublished - May 1 2004
EventThe 3rd International Conference on Spectroscopic Ellipsometry - Vienna, Austria
Duration: Jul 6 2003Jul 11 2003


  • Band structure
  • GeSn alloy
  • Interband transitions
  • Optical constants
  • Spectroscopic ellipsometry

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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