Ab initio pseudopotential calculations for electronic and geometric structure of mixed Si–Ge dimers on the Si(001)-(1×2) and Si(001)-(2×4) surfaces

Abstract

We report on ab initio pseudopotential calculations for electronic and geometric structure of mixed Si–Ge dimers on the Si(001)-(1×2) and Si(001)-(2×4) surfaces. The structural parameters obtained from our calculations provide some agreement with the recently proposed structure by Chen et al. based on adjacent substitutional Si–Ge dimers buckled in opposite directions. Dimer bonding and electronic states in the silicon band gap are also studied. It is noted that the c-(2×4) reconstruction provides a more efficient substrate relaxation mechanism than does the simple (1×2) reconstruction.