Structures of dislocations in GaAs and their modification by impurities

Local density functional theory is used to show that both {α} and {β} dislocations in GaAs are reconstructed. This is done by relaxing large 158-atom H-terminated clusters of GaAs containing 90^∘{} partial dislocations. The reconstruction is strongly influenced by impurities: acceptor pairs destroy the reconstruction of {β} partials but strengthen it for {α} dislocations. Donors have opposite effects. The implication of these results for the pinning of dislocations in GaAs is discussed.