Adsorption characteristics composition of Ge and Si on 4H-SiC(0 0 0 1) surface

Abstract

• For two different types of atoms, the most stable adsorption site is top site. • Compared with the adsorption of Si, Ge are more active on the adsorption surface. • Si Ge and Si Si bonds are formed between the adsorbed atom and the surface. • DOS indicates the presence of strong interactions of adsorbed atom and surface atoms. Silicon (Si) and germanium (Ge) are two important materials for hetero-epitaxy of 4H-silicon carbide (4H-SiC), so the First-principles calculation is employed to compare the difference of the adsorptions of Ge and Si atoms on the surface of 4H-SiC(0 0 0 1) by calculating the adsorption energy, geometric optimization, charge populations and density of state. For the two different types, four common adsorption models (top, hcp, fcc, bridge) are studied. The calculation results of adsorption energy show that, for two different types of atoms, compared with other sites, the most stable adsorption site is top site. At the same time, another important feature is that Si atom is more stable on Si surface, while Ge atom is easier to diffuse on Si surface. The results of the diffusion barrier indicates that, compared with the adsorption of Si atoms, Ge atoms are more active on the adsorption surface, which is consistent with the adsorption energy. Charge populations results shows that there is obvious charge transfer between the adsorbed atom and the surface atom, which implies that Si-Ge bonds and Si-Si bonds are formed between the adsorbed atom and the surface atom. The behaviors of the DOS of Si are qualitatively similar to that of Ge adsorption. It can be seen from the dos results that there are great resonance peaks, which indicates the presence of strong interactions of adsorbed atom and surface atoms, but extent of depreciation is different.