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Ge(110)/4H-SiC(0001) heterointerface and variations of XYZ coordinates and variation of distance are shown in (a) and (c–f), respectively. Ge(111)/4H-SiC(0001) heterointerface and variations of XYZ coordinates and variation of distance are shown in (b) and (g–j), respectively.
Source publication
First-principles calculation is employed to investigate atomic and electronic properties of Ge/SiC heterojunction with different Ge orientations. Based on the density functional theory, the work of adhesion, relaxation energy, density of states, and total charge density are calculated. It is shown that Ge(110)/4H-SiC(0001) heterointerface possesses...
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The research elaborates on the mechanical properties at the Al (111)/6H-SiC (0001) interface based on the density functional theory. Because of the difference in atom category at the interface of 6H-SiC (0001), it takes the C-terminated interface and Si-terminated interface into account. As indicated by the gross energy computing results at the two...
Citations
The theoretical calculations for the structural, thermodynamic, electrical and mechanical characteristics of aluminum and gallium were studied using ab initio principles. The Density Functional Theory (DFT) was used as the methodology, and it provides solutions to the Kohn-Sham equation. The elemental structures were obtained using Xcryden software, and the exchange correlation functions within the Perdew-Burke-Ernzerhof (PBE) functional were treated using the PAW pseudo-potentials and Generalized Gradient Approximation (GGA). The results obtained from the ab initio calculations engulfthat the structural properties of a(A), B(GPa), B'(GPa) and E(eV) for both elements studied. The parameters obtained for the mechanical properties C11, C12 and C44 were calculated for both metals. The elastic properties; G, B/G, E, µ, A and H were also calculated for both elements. The results obtained for aluminum shows the values of B, C', C11, C12 and C44 are 45, 3.9, 50.20, 47.6 and 31 respectively. For gallium we obtained 47, 4.03, 52.373, 44.313 and 29.0 corresponding to B, C', C11, C12 and C44 respectively.
The theoretical calculations for the structural, thermodynamic, electrical and mechanical characteristics of aluminum and gallium were studied using ab initio principles. The Density Functional Theory (DFT) was used as the methodology, and it provides solutions to the Kohn – Sham equation.
The elemental structures were obtained using Xcryden software, and the exchange correlation functions within the Perdew – Burke – Ernzerhof (PBE) functional were treated using the PAW pseudo – potentials and Generalized Gradient Approximation (GGA).
The results obtained from the ab initio calculations engulf that the structural properties of a(A), B(GPa), B’(GPa) and E(eV) for both elements studied. The parameters obtained for the mechanical properties C11, C12 and C44 were calculated for both metals. The elastic properties; G, B/G, E, µ, A and H were also calculated for both elements. The results obtained for aluminum shows the values of B, C’, C11, C12 and C44 are 45, 3.9, 50.20, 47.6 and 31 respectively. For gallium we obtained 47, 4.03, 52.373, 44.313 and 29.0 corresponding to B, C’, C11, C12 and C44 respectively.
In the production of SiC electronic devices, one of the main challenges is the fabrication of good Ohmic contacts due to the difficulty in finding the metals with low Schottky barriers of wide band gap SiC. Therefore, reducing the Schottky barrier height (SBH) at the metal/SiC interface is of great importance. In this paper, the effects of graphene intercalation on the SBH in different metals (Ag, Ti, Cu, Pd, Ni, Pt)/4H-SiC interfaces are studied by combining the average electrostatic potential and local density of states calculation methods based on first-principles plane wave pseudopotential density functional theory. The calculation results show that single-layer graphene intercalation can reduce the SBH of metal/4H-SiC contact. When the two layers of graphene are inserted, the SBH are further reduced. Especially, the contact between Ni and Ti exhibits negative SBH values, inferring that good Ohmic contacts are formed. When layers of graphene continue to increase, the SBH no longer changes obviously. By analyzing the differential charge density and the local density of states of the interface, the mechanism of SBH reduction may be that the dangling bonds on the SiC surface are saturated by the graphene C atoms and the influence of the metal-induced energy gap state at the interface is reduced, thereby reducing the interface state density. In addition, graphene and the corresponding new phases at the interface have low work functions. Moreover, an interfacial electric dipole layer may be formed at the SiC/graphene interface which also contributes to barrier reduction.
Compared with pure metal oxides, heterojunctions greatly change the response to gas by the synergistic effect of the interface. In this work, density functional theory was used to reveal the adsorption performance of H2 on the heterojunction under oxygen conditions. First, we determined the most reasonable heterojunction structure based on the adhesion work. According to the adsorption energy, the presence of SnO2(100)(I)/CoO(110)(II) made the adsorption of H2 more stable. The DOS results showed that the resistance of the heterojunction increased with H2 adsorption, following the same trend as that of CoO(110) with H2 adsorption, although that of the heterojunction increased more. The electron density and electron density difference indicated that the heterojunction improved the reaction between H2 and oxygen ions on CoO(110). However, the resistance of CoO(110)(II)/SnO2(100)(II) increased after H2 adsorption, contrary to the resistance change of SnO2(100). Besides, the bonding energy between H2 and the adsorption site became worse. The above results demonstrated that the presence of the heterojunction could indeed change the response trend and the adsorption behavior of H2. Interestingly, the adsorption sites and effects of H2 were different when two metal oxides were used as the substrate of the heterojunction, respectively.
Wetting and interfacial behavior of molten Al-(10, 20, 30, 40) at.%Ti alloys on C-terminated 4H–SiC at 1500 and 1550 °C were investigated experimentally, and theoretical bonding strength, structure stability and electronic structure of interfacial reaction products/C-terminated 4H–SiC interfaces were evaluated by first-principle calculations. The wetting experiments show that the Al–Ti/SiC systems present excellent wettability with contact angle of less than 15° except the Al–40Ti/SiC system performed at 1500 °C × 30 min. The SEM-EDS and TEM analyses demonstrate that the reaction products are mainly composed of Al4C3, TiC, Ti3SiC2, Ti5Si3CX and τ phase, and their formation and evolution can be mainly affected by the Ti concentration in the Al–Ti alloys and wetting temperature. Moreover, the calculated results show that the SiC/C-terminated TiC interface presents the highest work of separation and its electronic property reveals that the localization of electrons and formation of covalent bond between interfacial C atoms lead to the excellent bonding strength of SiC/TiC interface.
