The adsorption and diffusion of Si and Ge adatoms, near to the DB step on the hydrogenated (100) surface, were studied by using a first-principles total-energy method. Due to their isovalency, the Si and Ge adatoms exhibited similar behaviours with respect to their adsorption sites, adsorption geometries and diffusion pathways near to the step-edge. Nevertheless, the potential energy profiles for the adatoms had clear differences. The energy barrier for a Si adatom of the upper terrace, which was bound to the step edge, was 1.1eV. This barrier decreased to 0.6eV in the case of the Ge adatom. This difference was attributed to the bond-energy difference between Si-H and Ge-H, and to the H-mediated diffusion process. This suggested that Si and Ge adatoms behaved in differing ways on the hydrogenated (100) surface.

Chemical Differences in Surface Diffusion - Si and Ge Adatoms at the DB Step on the Hydrogenated Si(100) Surface S.Jeong, A.Oshiyama: Physical Review B, 1999, 60[16], R11269-72