Atomic and Electronic Structure of a Dissociated 60 degree Misfit Dislocation in Ge(x)Si(1-x)

Electron energy loss spectra and atomic column images were obtained from a dissociated 60^o misfit dislocation at the Ge_xSi_1-x substrate interface of a strained Si quantum well. Images agree with accepted structural models except near the 90^o dislocation. Silicon 2p_3/2EELS 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^o dislocation show a similar splitting as well as in-gap defect electronic states. Spectra from the 90^o 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.