Core-level photo-emission spectroscopy was used to study the absorption and growth of Si which had been grown onto 2 x 1 (100) Ge surfaces by means of molecular beam epitaxy. The populations of Si and Ge atoms in the surface layer were monitored by measuring the intensities of the surface-shifted Si and Ge core-level components. When a few Si atomic layers had been deposited at 450C, the top layer which formed the 2 x 1 reconstruction consisted of Ge atoms alone. The tendency of Si atoms to move below the surface persisted even for growth near to room temperature.

D.S.Lin, T.Miller, T.C.Chiang: Physical Review B, 1992, 45[19], 11415-8