The surface of a Si substrate was partially covered with an over-layer of Ge. The surface of the Ge sheet was then irradiated with 7MeV electrons at 40C in a vacuum to a fluence of 1018/cm2. The surface diffusion of Ge atoms on the Si substrate was confirmed by using atomic force microscopy and secondary-ion mass spectrometry.

T.Wada, H.Fujimoto, H.Masuda: Materials Science Forum, 1995, 196-201, 1625-30