Surface relaxation and oxygen adsorption behavior of different SiC polytypes: afirst-principles study

Abstract

The surface relaxations and oxygen adsorptions on C- and Si-terminated 3C-SiC(111)and 2H/4H/6H-SiC(0001) surfaces are systematically studied using densityfunctional theory (DFT) calculations. First, the general surface relaxation trends ofdifferent SiC surfaces are explained using the electrostatic interaction and thecalculation results of spin density distributions. In the second part of the presentwork, the relations between adsorption energies and stacking sequence are studied.We find that the adsorption energies of bridge, hollow-3 and T4 configurationson Si-terminated SiC surfaces increase with the increasing of the real numberT(I), which is a translation of the polytypic sequence and quantifies the amount of ‘h’ character of the surface and of the deeper layers, while the energies of the on-topconfigurations on Si-terminated SiC surfaces and of all configurations on the C-terminatedSiC surface seem to depend only on the stacking orientation of the topmost layer and noton the subsequent ones.