Atomistic structure of stacking faults in a commercial GaAs:Si wafer revealed by cross-sectional scanning tunneling microscopy

A Frank-type stacking fault bounded by a partial dislocation, about a few nanometers in size, was observed in a commercial GaAs:Si wafer (with the Si concentration of ∼1018cm-3) annealed at the temperature of about 950 K, by cross-sectional scanning tunneling microscopy. There existed no charge around the stacking fault, unlike in heavily Si-doped GaAs. There was a localized energy level associated with the stacking fault, as expected theoretically in the pure stacking fault in which Si atoms do not exist.