H coverage dependence of Si(001) homoepitaxy

We have investigated the role of surface H in Si(001) homoepitaxy using in situ medium energy ion scattering and time-of-flight H recoil detection. The addition of submonolayer coverages of atomic H produce relatively modest effects on epitaxy for ${\mathit{T}}_{\mathit{g}}$≤200 °C. But at surface H concentrations surpassing 1 monolayer, we find a disruption of epitaxy, which is delayed to higher temperatures than on bare Si(001). The degradation of epitaxy correlates with the presence of surface dihydrides, which break the dimer configuration of Si(001).