Search

The Nb 2 NT 2 /MoTe 2 heterojunction shows n -type Ohmic contacts in O terminal system, while p -type and n -type Schottky contacts are formed in F and OH terminal systems, respectively, which makes the system suitable for electron device in terms of bandgap engineering controlling. [Display omitted] • The Nb 2 NT 2 /MoTe 2 heterostructure is dominated by vdW interaction. • The equilibrium interlayer spacing is within the range of 3.061 Å to 3.328 Å. • 0.12 e per cell spontaneously transfer from MoTe 2 to Nb 2 NO 2 layer. • n -type Ohmic contacts are formed in O terminal system. • Schottky contacts are formed in F and OH terminal systems. In the current effort, a novel attempt to construct heterojunctions using Nb 2 N two-dimensional MXene materials with fascinating property and MoTe 2 transition metal disulfide compounds is proposed. The effect of vertical strain on the electronic structure and interfacial contact properties of the heterojunction is investigated by first principles calculations. The O, F, and OH functional groups prefer to be adsorbed on top of the N atoms of the Nb 2 N MXene material. The configuration III of heterojunction has the lowest energy and stable model, and the equilibrium layer spacing is within the range of 3.061 Å to 3.328 Å, indicating that they belong to typical vdW heterojunctions. The large work function difference between the two components induces the transfer and rearrangement of charge. 0.12 e per cell spontaneously transfer from MoTe 2 to Nb 2 NO 2 layer. In contrast, the Nb 2 NF 2 and Nb 2 N(OH) 2 layers transfer 0.01 e and 0.21 e to the MoTe 2 layer, respectively. n -type Ohmic contacts are formed in O terminal system, while p-type and n -type Schottky contacts are formed in F and OH terminal systems, respectively. Additionally, for vertical strain, with the decrease of the layer spacing, the p-type Schottky barrier height (SBH) decreases from 0.270 eV to 0.095 eV in former system, meanwhile the n -type Schottky barrier height in the latter system also decreases from 0.260 eV to 0.156 eV. These regulations of interest lays a theoretical foundation for bandgap engineering and Schottky junction preparation and opens a window into MXene-based heterojunction electron device. [ABSTRACT FROM AUTHOR]

• The graphene/GaP heterostructure is dominated by vdW interaction. • The equilibrium interlayer spacing is 3.40 Å and the binding energy is −39.35 meV. • A tiny bandgap of 20 meV has opened at the Dirac point. • The interlayer distance and biaxial strain may change the contact mode. • A conversion from p-type Schottky to p-type Ohmic contact is present. Establishing the desired heterostructures by assembling suitable semiconductor materials has shown significant potential for applications in next-generation micro-nano electronic devices. In this present contribution, we demonstrate the geometric structure and electronic properties of graphene/GaP heterostructure by first-principles calculations. It is found that the heterostructure is characterized by weak interlayer coupling accompanying the stable layer spacing of 3.40 Å and binding energy of −39.35 meV, meaning that the interlayer is dominated by van der Waals (vdW) force. The electronic band structure of free-standing graphene and GaP monolayers are preserved well. Meanwhile, a tiny bandgap of approximatively 20 meV at the Dirac point of graphene is opened, which is attributed to the breakdown of sublattice symmetry. In the ground state, the Schottky contact of p -type is present with the n -type and p -type SBH of 1.71 eV and 0.10 eV, respectively, which can be effectively induced by imposing interlayer coupling as well as in-plane strains. Especially, the transition of p -Schottky contact to p -Ohmic contact occurs when the layer spacing decreases to 3.20 Å or the strain increases to +2 %. These theoretical results may offer potential guiding principle in future electronic devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] BaCu(B2O5) is added to the multi-ions doped SrTiO3 ceramics as sintering aid. [•] The sintering temperature is decreased from 1300°C to 1075°C. [•] The incorporation of Ba2+ into the matrix increases the dielectric constant. [•] The breakdown strength increases due to the decrease of grain size and porosity. [•] The dissolution of BCB contributes to the improvement of dielectric properties. [ABSTRACT FROM AUTHOR]

Abstract: The correlation of crystal structure and microwave dielectric properties for Zn(Ti1−x Sn x )Nb2O8 ceramics were investigated. The Zn(Ti1−x Sn x )Nb2O8 ceramics contained ZnTiNb2O8 and an unknown Columbite-type phase. The columbite structure phase with increasing degree of ordering led to decrease of dielectric constant, increase of Qf and τ f . The ZnTiNb2O8 with decreasing cation valence led to increase of τ f . The typical values were: ɛ =30.88, Qf =43,500GHz, τ f =−54.32×10−6/°C. [ABSTRACT FROM AUTHOR]