科研之友
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摘要
First-principles, spin-polarized local-density-functional calculations are used to model interstitial iron (Fe(i)) and its complexes with substitutional aluminum in dilute Si(x)Ge(1-x) alloys (x<8%). We considered both the effect of direct bonding between Fei or Fe(i)Al with Ge atoms in the x -> 0 limit and the evolution of the defect properties with the alloy composition. It is found that Fei prefers Si-rich regions, but when placed near a Ge atom, its (0/+) level is shifted toward the conduction band. However, the ionization energy of Fe((+/+2))-Al(-) is only slightly changed by the presence of neighboring Ge atoms in the proximity. It is also found that indirect alloying effects shift the donor levels of Fe(i) and FeAl at a fast rate toward the valence band. The acceptor levels, however, remain approximately at the same distance from E(v).
- 出版日期2008-9
