Atomic and electronic structure of a dissociated 60° misfit dislocation in Ge_xSi(_1-x)

Electron energy loss spectroscpy (EELS) spectra and atomic column images were obtained from a dissociated 60° misfit dislocation at the GexSi1-x substrate interface of a strained Si quantum well. Silicon 2p3/2 EELS spectra from the stacking fault show splitting of the L1 conduction band minimum caused by third-neighbor interactions at the fault. Spectra from the 30° dislocation show a similar splitting as well as in-gap defect electronic states. Spectra from the 90° dislocation also show evidence of in-gap states but do not show the L1 splitting. An extended core structure based on a double period pairing reconstruction may be able to explain this lack of L1 splitting. © 1999 The American Physical Society.