Energetics and electronic states of Si34-xGex clathrate alloys have been investigated. The atomistic structures, the equations of state, and the lineup of band structures for these clathrates are calculated using the Vanderbilt ultra-soft pseudopotential method within the local-density-functional formalism. Some of these Si34-xGex clathrate alloys with an ideal Fd3̄m symmetry are found to have direct band gap at the π/a(111) (L) point in the Brillouin zone. The entire band gap of the Si34-xGex alloys is predicted to range between 1.2 and 2.0 eV. The total-energy difference between these clathrate alloys and the well-known sp3 Si-Ge alloys is less than 0.08 eV/atom. A method to synthesize these clathrate systems is also discussed. These Si-Ge clathrate alloys may find applications in optoelectronics semiconductor devices based on the Group-IV elements.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||出版済み - 9月 15 2000|
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