The role which was played by H in the growth of Ge on a Si(001)-2 x 1 surface was determined by means of scanning tunnelling microscopy and medium-energy ion-scattering spectroscopy. The adsorbed H was found to increase the number of equilibrium adsorption sites, remove the diffusion anisotropy, and decrease the diffusivity of Ge adatom; as predicted by previous first-principles calculations. By using a dynamically supplied atomic H flux of some 2 monolayers per second, layer-by-layer growth was achieved by preventing growth of the hut cluster beyond the known critical thickness. Monolayer of Ge which were grown in the presence of the H surfactant were strained, whereas those grown without it were relaxed.

Hydrogen-Surfactant Mediated Growth of Ge on Si(001). S.J.Kahng, Y.H.Ha, J.Y.Park, S.Kim, D.W.Moon, Y.Kuk: Physical Review Letters, 1998, 80[22], 4931-4