The effect of coincident atomic hydrogen on the gas-source molecular beam epitaxial growth of silicon from disilane

The interaction of atomic hydrogen with both the clean Si(1 0 0) surface, and this same surface under conditions leading to steady-state epitaxial growth of Si from the reaction of disilane, Si2H6, has been examined. Reflectance anisotropy spectroscopy has been employed to measure the hydrogen adatom coverage on vicinal Si(1 0 0) surfaces as a function of atomic hydrogen exposure at differing substrate temperatures and differing atomic hydrogen fluxes. This set of experimental data can be fit well by a “hot-precursor” model that includes the elementary steps of adsorption, abstraction, migration, and desorption of atomic hydrogen, and where we account explicitly for adsorption site occupancy. Reflection high-energy electron diffraction has been used to quantify the effect of atomic hydrogen on the gas-source molecular beam epitaxial growth of Si from Si2H6. We observe suppression of the epitaxial growth rate by atomic hydrogen under a variety of reaction conditions. This set of data are described well by a model that combines rate expressions for the dissociative adsorption of Si2H6, the adsorption of atomic hydrogen, and the recombinative desorption of molecular hydrogen from the Si(1 0 0) surface.