Theoretical study of strain-induced step configuration changes on vicinal Si(001) by the growth of Ge

Abstract

The initial stage of growing Ge on single-domain vicinal Si(001) with a large angle of misorientation has been studied theoretically by the modified Keating model and compared with RHEED and STM experiments. The experimentally observed conversion from the DB step configuration, where all dimer rows are normal to the step edges, to a DA-like step configuration, where dimer rows on one terrace are parallel to the step edges, at Ge coverages larger than 1 ML is identified by our calculations. Our results show that this DA-like step is in fact a pair of steps of single atomic height: SA+SB, with a very wide SA terrace and an SB tooth of about 10 Å. This new step configuration is energetically favoured over DA and DB step configurations.