Theoretical study of Sn and Te adsorption over graphene from ab initio calculations

In this work, we report on theoretical calculations for the adsorption of both Sn and Te atoms over a graphene monolayer. Our obtained results show that Sn is chemisorbed over a graphene C–C bond, once the presence of Sn over the substrate changes some of graphene’s C–C sp2-like bond character to a more covalently reactive sp3-like one. On the other hand, Te is physisorbed over a C atom of the graphene sheet, since it is weakly connected to the surface atoms by van der Waals’ forces. However, both Sn and Te are extremely mobile over the graphene monolayer because the energy barriers between the adsorption sites are very small. Considering that SiC surfaces passivated with graphene enhance the strength of the C–Sn bonds in the MBE growth procedure, our results, theoretically, confirm the growth of a SnTe layer on graphene.