Ge (001) surface was irradiated by 60keV Sn ions to a fluence of 8 x 1018 ions/m2 at a controlled substrate temperature, and the formation of defects was investigated. A damaged layer of about 50nm in thickness was formed on the surface at 150K. In the case of irradiation at room temperature, a damaged layer was also created, but voids of about 15nm diameter were created near the top surface. This result was explained by the high mobility of vacancies during irradiation at room temperature, and it was confirmed that the void formation process was dominated by the migration of induced point defects.

Formation of Defect Structure on Ge Surface by Ion Irradiation at Controlled Substrate Temperature. N.Nitta, T.Hasegawa, H.Yasuda, Y.Hayashi, T.Yoshiie, M.Taniwaki: Materials Transactions, 2011, 52[2], 127-9