Srtio ₃ -gaas ( Gap ) Heterojunction Structure And Electronic Properties Of

The electronic properties of the heterojunctions between the ferroelectric crystal SrTiO₃ and photoelectric material GaAs and GaP are systematically studied by the first-principles calculations of the pseudo potential plane wave based on density functional theory.We analyze the crystal structures and electronic properties of SrTiO₃, GaAs and GaP. The Ti-O bond and the Sr-O bond in the SrTiO₃ are explained. For the zinc blendes of GaAs and GaP, the top of the valence band, the bottom of the conduction band, the Ga-As bond and the Ga-P bond are discussed. We research their surfaces on the basis of crystal analysis. The (001) SrTiO₃ surface is weekly polar. The surface-Ⅰis more stable than surface-Ⅱin most chemical conditions. The (001) surfaces of GaAs and GaP is polar. We compare the surfaces' properties with and without the H-saturation. We can get that the H-saturation is important for shielding the under surface.So, we use the H-saturation skill to eliminate the dangling bonds in the under surface. On the basis of the surfaces, we discuss the theoretical models by analyzing the experiment reports of the SrTiO₃-GaAs heterojunctions. We get the matching interface of SrTiO₃ and GaAs, which is the (001) SrTiO₃ and the (001) GaAs. But the GaAs lattice need rotate by 45°(or the SrTiO₃ lattice need rotate by 45°) to [110]. Because we know the SrO termination is more stable. We make the SrO termination to be our interface. By the interfacial calculation and analysis, we find that SrO-As has lower energy and the action of their interfaces is stronger, which is more stable.For the SrTiO₃-GaP heterojunctions, we base on the analysis of the SrTiO₃-GaAs heterojunctions. We get the matching interface of SrTiO₃ and GaP, which is the (001) SrTiO₃ and the (001) GaP. But the GaP lattice need rotate by 45°(or the SrTiO₃ lattice need rotate by 45°) to [110]. By the interfacial calculation and analysis, we find that SrO-P has lower energy and the action of their interfaces is stronger, which is more stable.It is studied theoretically that is the electronic properties of the SrTiO₃-GaAs and SrTiO₃-GaP heterojunctions. We get the stable interfaces. The stable interfaces in the SrTiO₃-GaAs heterojunction is the SrO-As interface of SrTiO₃(001)||GaAs(001) and SrTiO₃[110]||GaAs[100]. The stable interfaces in the SrTiO₃-GaP heterojunction is the SrO-P interface of SrTiO₃(001)||GaP(001) and SrTiO₃[110]||GaP[100].