Energetic evidence for mixed dimer growth on the Si(001)/Ge(2x1) surface

Recent experimental evidence has indicated that the predominant growth mode of Ge on the Si(001)(2 x 1) surface at submonolayer coverage is by the formation of mixed Si-Ge dimers. We present results of ab initio pseudopotential calculations for the half-monolayer and full-monolayer Ge covered Si(001)(2 x 1) surface. Comparison of the total energy results for these surfaces supports the picture of mixed dimer formation for the half-monolayer coverage, and limited interdiffusion at higher coverages.