Impact of boron on the step-free area formation on Si(111) mesa structures

Abstract

We report about the influence of boron (B) on surface morphology of Si layers grown by molecular beam epitaxy on Si(111) mesas. Dimension of step-free mesa areas is reduced in comparison to pristine Si and scales with the B-coverage. This can be explained by a reduced mass transport on the Si surface in the presence of B-induced √3 × √3 surface structure which is due to a reduced Si equilibrium free adatom density. We demonstrate that a suitable combination of initial B coverage and Si layer thickness results in large step free areas and B doping concentration up to 4 × 1018 cm−3.