Atomic and Electronic Structure of a Dissociated 60° Misfit Dislocation inGexSi(1−x)

Abstract

Electron energy loss spectroscpy (EELS) spectra and atomic column images were obtained from a dissociated 60\ifmmode^\circ\else\textdegree\fi{} misfit dislocation at the ${\mathrm{Ge}}_{x}{\mathrm{Si}}_{1\ensuremath{-}x}$ substrate interface of a strained Si quantum well. Silicon ${2p}_{3/2}$ EELS spectra from the stacking fault show splitting of the ${L}_{1}$ conduction band minimum caused by third-neighbor interactions at the fault. Spectra from the 30\ifmmode^\circ\else\textdegree\fi{} dislocation show a similar splitting as well as in-gap defect electronic states. Spectra from the 90\ifmmode^\circ\else\textdegree\fi{} dislocation also show evidence of in-gap states but do not show the ${L}_{1}$ splitting. An extended core structure based on a double period pairing reconstruction may be able to explain this lack of ${L}_{1}$ splitting.