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Title: Properties of the exotic metastable ST12 germanium allotrope

The optical and electronic properties of semiconducting materials are of great importance to a vast range of contemporary technologies. Diamond-cubic germanium is a well-known semiconductor, although other ‘exotic’ forms may possess distinct properties. In particular, there is currently no consensus for the band gap and electronic structure of ST12-Ge (tP12, P4 32 12) due to experimental limitations in sample preparation and varying theoretical predictions. Here we report clear experimental and theoretical evidence for the intrinsic properties of ST12-Ge, including the first optical measurements on bulk samples. Phase-pure bulk samples of ST12-Ge were synthesized, and the structure and purity were verified using powder X-ray diffraction, transmission electron microscopy, Raman and wavelength/energy dispersive X-ray spectroscopy. Lastly, optical measurements indicate that ST12-Ge is a semiconductor with an indirect band gap of 0.59 eV and a direct optical transition at 0.74 eV, which is in good agreement with electrical transport measurements and our first-principles calculations.
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [2]
  1. Carnegie Institution of Washington, Washington, D.C. (United States); Yanshan Univ., Qinhuangdao (China)
  2. Carnegie Institution of Washington, Washington, D.C. (United States)
  3. Carnegie Institution of Washington, Washington, D.C. (United States); Center for High Pressure Science and Technology Advanced Research, Shanghai (China)
  4. Yanshan Univ., Qinhuangdao (China)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Carnegie Institution of Washington, Washington, D.C. (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; electronic devices; electronic properties and materials; solar cells
OSTI Identifier: