The influence of additional atomic hydrogen on the monolayer growth of Ge on Si(100) studied by STM

The influence of additional atomic hydrogen (H) on the monolayer growth of Ge on Si(100) surfaces has been studied using scanning tunneling microscopy (STM). The Ge monolayer films have been grown on Si(100) with and without the additional H by solid-source molecular beam epitaxy (SSMBE). Up to the Ge coverage of 3 ML, the addition of H atoms during Ge growth causes an increase in the density of the two-dimensional (2D) growth nuclei and in a promotion of the multiple nucleation and layer growth. The anisotropic 2D island shape is also changed to the isotropic one by the H addition. Above 3 ML, the formation of 3D islands is suppressed with an increase in the additional H flux. These phenomena can be explained by reducing the diffusion length of Ge adatoms and the step energy by terminating dangling bonds with H atoms.