Initial growth stage of a highly mismatched strontium film on a hydrogen-terminated silicon (111) surface

We report the formation of an atomically abrupt interface without strain in a strontium film using a hydrogen buffer layer on silicon, in spite of large lattice mismatch such as 12%. The onset of the initial growth stage of strontium film with its bulk lattice constant occurs with one atomic layer deposition. The interfacial monoatomic layer of hydrogen together with the first one atomic layer of strontium acts as an effective buffer layer. Our results provide microscopic evidence of heteroepitaxial growth of the strain-free film with the atomically abrupt interface in a highly mismatched system.