We first address the chemistry of the metal precursors interacting on H-terminated and NHx-terminated metal surfaces. To study H-terminations, a full monolayer (ML) coverage of hydrogen, i.e. 9 H atoms for (2×2) supercell, is placed on top of surface Si atoms. After hydrogen passivation, the surface Si atoms have formed the well-known Si-Si dimer with bond length at 2.42Å, while for bare Si(100), the Si-Si distances of surface Si atoms are at 3.84Å. The atomic structure of this model is shown in Figure of the SI.