Theoretical study of the initial stages of Ba growth on Si(100) substrate

We present theoretical study based on DFT calculations of the initial stages of Ba growth on Si(100) substrate. The obtained results indicate the possibility of coexistence of the inter-row and intra-row Ba monomers, as predicted by reported earlier STM measurements – the inter-row configuration has only 0.15 eV lower energy than the intra-row system. The detailed analysis of the atomic and electronic structures of both monomers have been performed. It was found that in all cases Ba adatom tends to interact with silicon surface atoms with higher vertical position. Presented study shows that the presence of both types of Ba monomer increases the local chemical reactivity of silicon surface, however this effect is stronger for the inter-row configuration. It was shown that such modification of substrate reactivity influences the form of the further aggregation of Ba adatoms. The obtained results indicate the tendency to formation by adatoms of linear-zigzag chains across the surface dimer rows, which seems to be in the agreement with reported earlier STM data.