Defect levels of dangling bonds in Si and Ge were determined within their respective band gaps via the use of hybrid density functionals. In order to check the approach, the dangling bond in Si was first considered. Two well-separated defect levels were found; in excellent agreement with their measured location. Application to the dangling bond in Ge yielded 2 very close defect levels which lay just above the valence band; consistent with the experimental location of the charge neutrality level. The occurrence of negative-U behavior led to a reduced fraction of neutral dangling bonds, thus suppressing the electron-spin-resonance activity.

Defect Levels of Dangling Bonds in Silicon and Germanium through Hybrid Functional. P.Broqvist, A.Alkauskas, A.Pasquarello: Physical Review B, 2008, 78[7], 075203 (5pp)