Void formation in annealed proton-bombarded GaAs

Radiation damage in GaAs bombarded to a dose of 1017 protons cm−2 at 300 keV is directly observable by cross-sectional transmission electron microscopy as a dark diffuse structure. The densest region of this damage lies at the depth predicted by the Lindhard-Scharff-Schiott theory for proton penetration. During anneal for 15 min at 800–1000 °C the crystal recovers with the formation of dislocation networks interspersed with voids. The voids take on the form of dodecahedrons and produce a swelling of 2.5% at the peak of the damage distribution for samples annealed at 1000 °C.