Analysis of buried heterointerfacial hydrogen in highly lattice-mismatched epitaxy on silicon

We realized the epitaxial growth of a Sr layer on Si(111) with an atomically abrupt heterointerface – in spite of its large lattice mismatch (12%) with Si – by introducing a monoatomic layer of H on Si. In order to identify the buried H, we carried out a combination analysis involving neutron reflectometry and resonant nuclear reaction of 1H(15N,αγ)12C analysis. We found different neutron reflectivity profiles resulting from a contrast variation between the H and D atoms at the buried heterointerface. Furthermore, the depth γ-ray intensity profiles revealed that the H at the heterointerface acts as an effective buffer layer that enables it to manage the highly mismatched epitaxy on Si.