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Void formation and structure change by heavy ion irradiation were investigated in GaSb and InSb thin films. The voids were formed after irradiation in both materials. The average diameter of the voids was about 15 nm in GaSb and 20 nm in InSb irradiated with 60 keV Sn þ ions to a fluence of 0:25 Â 10 18 ions/m 2 at room temperature. The void size in InSb is larger than that in GaSb. The large void size is quantitatively explained by the amount of induced vacancies obtained by the SRIM code simulation. The Debye-Scherrer rings were observed in the SAED patterns on both materials. The structure changes into a polycrystal by ion irradiation. Additionally, the 200 superlattice reflections in the [001] net pattern were almost absent, and the streak pattern along the h110i direction was observed in InSb. It is considered that the anti phase domains of different lengths are formed by ion irradiation. Ion irradiation transforms the structure of InSb from chemical ordering to chemical disordering via the formation of anti phase boundaries.

Ge (001) surface was irradiated by 60 keV Sn ions to a fluence of 8 Â 10 18 ions/m 2 at a controlled substrate temperature, and the formation of defects was investigated. A damaged layer of about 50 nm thickness was formed on the surface at 150 K. In the case of irradiation at room temperature, a damaged layer was also created, but voids of about 15 nm diameter were created near the top surface. This result is explained by the high mobility of vacancies during irradiation at room temperature, and it is confirmed that the void formation process is dominated by the migration of induced point defects.

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