Electronic Properties Of Heterostructures Research Articles

First-principles insights of electronic properties of Blue Phosphorus/MoSi2N4 van der Waals heterostructure via vertical electric field and biaxial strain

Very recently, a new kind of 2D transition metal nitride , MoSi 2 N 4 , has been attracting considerable attention due to its successful synthesis and outstanding properties. To further explore its novel properties and applications for nanodevices , we have proposed a van der Waals (vdW) heterostructure composed of MoSi 2 N 4 and Blue Phosphorus (BlueP) monolayers and systematically studied its electronic properties with first-principles calculations. The results show that the heterostructure exhibits a type-II band alignment, with the conduction band minimum (CBM) and valence band maximum (VBM) located in BlueP and MoSi 2 N 4 layers, respectively. Furthermore, the electronic properties of heterostructure are not sensitive to different stacking patterns while can be significantly modulated by applying an external electric field or a biaxial strain. When applying the electronic field, the band gap shows linear variation with the electric field, and a semiconductor-to-metal transition is observed under the strong electric field. When applying the biaxial strain, the band alignment can be transformed from type-II to type-I. This work provides theoretical guidance for design of flexible nano-electronic and optoelectronic devices based on the BlueP/MoSi 2 N 4 heterostructure. • The BlueP/MoSi 2 N 4 heterostructure exhibits a type-II band alignment. • The electronic properties of heterostructure are not sensitive to diverse stacking patterns. • The electronic properties of heterostructure can be tuned by external electric field or biaxial strain. • A semiconductor-to-metal transition takes place when applying a strong electric field. • Band alignment transition from type-II to type-I has been observed under the effect of biaxial strain.

Interface engineering of transition metal dichalcogenide/GaN heterostructures: Modified broadband for photoelectronic performance

The GaN-based heterostructures are widely used in optoelectronic devices, but the complex surface reconstructions and lattice mismatch greatly limit the applications. The stacking of two-dimensional transition metal dichalcogenide (TMD = MoS2, MoSSe and MoSe2) monolayers on reconstructed GaN surface not only effectively overcomes the larger mismatch, but also brings about novel electronic and optical properties. By adopting the reconstructed GaN (0001) surface with adatoms (N-ter GaN and Ga-ter GaN), the influences of complicated surface conditions on the electronic properties of heterostructures have been investigated. The passivated N-ter and Ga-ter GaN surfaces push the mid-gap states to the valence bands, giving rise to small bandgaps in heterostructures. The charge transfer between Ga-ter GaN surface and TMD monolayers occurs much easier than that across the TMD/N-ter GaN interfaces, which induces stronger interfacial interaction and larger valence band offset (VBO). The band alignment can be switched between type-I and type-II by assembling different TMD monolayers, that is, MoS2/N-ter GaN and MoS2/Ga-ter GaN are type-II, and the others are type-I. The absorption of visible light is enhanced in all considered TMD/reconstructed GaN heterostructures. Additionally, MoSe2/Ga-ter GaN and MoSSe/N-ter GaN have larger conductor band offset (CBO) of 1.32 eV and 1.29 eV, respectively, extending the range from deep ultraviolet to infrared regime. Our results revel that the TMD/reconstructed GaN heterostructures may be used for high-performance broadband photoelectronic devices.

First Principles Investigations of Structural, Electronic and Transport Properties of $$\hbox {BiI}_3/\hbox {ZrS}_2$$ van der Waals Heterostructure: A Thermoelectric Perspective

Using density functional theory and semi-classical Boltzmann transport theory, we have studied structural, electronic and transport properties of a van der Waals vertical heterostructure of $$\hbox {BiI}_3$$ and $$\hbox {ZrS}_2$$ . The elastic constant of the heterostructure is larger than the individual monolayers. Further it has a direct band gap that is smaller than the monolayers. The interaction between the layers results in subtle changes in the electronic properties of the heterostructure such that its transport properties are also affected. In particular, we find that the relaxation time of electrons is significantly increased in the heterostructure such that its power factor is about ten and one hundred times larger than that of a monolayer of $$\hbox {ZrS}_2$$ and $$\hbox {BiI}_3$$ , respectively, indicating that the maximum power output from a thermoelectric device made of an n-doped heterostructure is larger than that obtained from the individual components. Our results suggest that this novel heterostructure is a possible candidate for n-type thermoelectrics.

Electronic and structural properties of novel monolayer molybdenum disulfide and boron phosphide heterostructures

Abstract Inspired by the huge surge of interests devoted to the nanoelectronic applications of van der Waals (vdW) heterostructures, we have examined the structural and electronic properties of the heterostructure systems composed of single-layer boron phosphide (BP) and molybdenum disulfide (MoS2) monolayers using the density functional theory calculations. Various stacking patterns were considered to form favorable hybrid systems consisting of MoS2 and BP monolayers. In this work, we confirmed the stability of the constructed heterostructures by calculating the binding energies. Our results demonstrated that all the considered patterns of MoS2/BP heterostructures exhibited semiconducting electronic properties. Small band gaps are created around the Fermi level for all the stacking arrangements, which are lower than the band gaps of bare MoS2 and BP monolayers. Our designed MoS2/BP vdW heterostructures may be a prominent candidate for applications in future nanoscale electronic devices.

First-principles predication of facet-dependent electronic and optical properties in InSe/GaAs heterostructure with potential in solar energy utilization

Building two-dimensional (2D) heterostructure emerges novel properties, attracting great attention in materials science. Here, we design InSe/GaAs heterostructures and explore their novel photoelectric properties using first-principles method. Heterostructures have been shown to be direct bandgap semiconductors with type-II band alignment. Meanwhile, the electronic properties of heterostructures are not only sensitive to stacking model but also strongly dependent on the facet of GaAs contacting InSe. The heterostructures, with As-facet contacting InSe, are confirmed to be preeminent photocatalyst for water splitting. While formed with Ga-facet, heterostructures can be used as appropriate photovoltaic material. All heterostructures possess broad absorption range, with high absorption coefficients (∼105). Besides, the carrier mobilities are outstanding. Therefore, the above prediction results make the InSe/GaAs heterostructures promising to be used in solar energy utilization.

Structural and electronic properties of heterointerface composed of non-polar oxides: SrTiO3 and ferroelectric BaTiO3

We investigate the structural and electronic properties of heterostructure composed of two insulators: ferroelectric BaTiO3 and dielectric SrTiO3, by means of ab initio calculations. Both components of the heterostructure are non-polar in the simple ionic limit. We consider three types of BaTiO3 polarization: non-polar, dipoles towards the interface, and dipoles towards the surface. For the non-polar heterostructure, we obtain that system remains an insulator up to eight BaTiO3 overlayers. However, we show that polarization in the BTO slab induces conductivity. We analyze an impact of ferroelectric polarization onto conducting properties, as well as a possibility of switchable and controllable metal-insulator transition.

Tuning electronic properties of InSe/arsenene heterostructure by external electric field and uniaxial strain

First-principles based on density functional theory (DFT) are used to calculate the structural and electronic properties of InSe/arsenene heterostructure. The results show that the InSe/arsenene bilayer forms a type-II van der Waals heterostructure with a direct band gap of 0.876 eV, which is favorable for the separation of photogenerated electron-hole pairs. The properties of InSe/arsenene heterojunction can be effectively regulated by applying an external electric field and uniaxial strain. When an external electric field is applied, the heterostructure experiences a transition from semiconductor to metal. In addition, due to the presence of built-in electric field, the positive and negative electric fields have different effects on the electronic properties of heterostructure. When uniaxial strain is applied, the heterostructure can withstand larger tensile strain than compression strain without damaging the structure and the band gap is more easily decreased by X-direction strain. In addition, the heterostructure undergoes a direct-indirect bandgap transition under strain. When compressive strain is applied in the Y direction, especially ε < −2%, the heterostructure possesses a higher carrier mobility while maintaining direct bandgap characteristics. Our results show that the new InSe/arsenene heterostructure has great potential for applications in electronic and optoelectronic devices.

Structural, electronic, vibrational, and elastic properties of graphene/ MoS2 bilayer heterostructures

Graphene/MoS$_2$ van der Waals (vdW) heterostructures have promising technological applications due to their unique properties and functionalities. Many experimental and theoretical research groups across the globe have made outstanding contributions to benchmark the properties of graphene/MoS$_2$ heterostructures. Even though some research groups have already made an attempt to model the graphene/MoS$_2$ heterostructures using {\it first-principles} calculations, there exists several discrepancies in the results from different theoretical research groups and the experimental findings. In the present work, we revisit this problem by first principles approach and address the existing discrepancies about the interlayer spacing between graphene and MoS$_2$ monolayers in graphene/MoS$_2$ heterostructures, and the location of Dirac points near Fermi-level. We find that the Tkatchenko--Scheffler method efficiently evaluates the long-range vdW interactions and accurately predicts interlayer spacing between graphene and MoS$_2$ sheets. We further investigate the electronic, mechanical and vibrational properties of the optimized graphene/MoS$_2$ heterostructures created using 5$\times$5/4$\times$4 and 4$\times$4/3$\times$3 supercell geometries having different magnitudes of lattice mismatch. The effect of the varying interlayer spacing on the electronic properties of heterostructures is discussed. Our phonon calculations reveal that the interlayer shear and breathing phonon modes, which are very sensitive to the weak vdW interactions, play vital role in describing the thermal properties of the studied systems. The thermodynamic and elastic properties of heterostructures are further discussed. A comparison between our results and the results reported from other research groups is presented.

Characterization of electronic structures from CdS/Si nanoheterostructure array based on silicon nanoporous pillar array

The electronic properties of heterostructures are very important to its applications in the field of optoelectronic devices. Understanding and control of electronic properties are very necessary. CdS/Si nanoheterostructure array have been fabricated through growing CdS nanocrystals on the silicon nanoporous pillar array using a chemical bath deposition method. The electronic properties of CdS nanoheterostructure array have been investigated by the current–voltage, complex impedance spectroscopy and capacitance–voltage techniques. The onset voltages, characteristic frequency and built-in potential are gradually increased with increasing the annealing temperature. It is indicated that the electronic structures of CdS/Si nanoheterostructure array can be tuned through the annealing treatments.

Local electronic properties and magnetism of (Cd,Mn)Te quantum wells

The electronic properties of heterostructures containing (Cd,Mn)Te quantum wells are probed by soft x-ray spectroscopies. We provide experimental evidence that Mn ions are in the Mn2+ (3d5) electronic configuration, and rule out the possibility that charge transfer and crystal field effects can reduce the magnetic moment of each Mn ion to the value (0.61) extracted from the fitting of the magnetization curve with a Brillouin function. These results confirm that the observed magnetic behavior can be correctly explained by assuming an antiferromagnetic coupling between nearest-neighbor S=5/2 Mn2+ ions, rather than a paramagnetic response from an ensemble of low-spin Mn ions.

Nonequilibrium transport and optical properties of model metal–Mott-insulator–metal heterostructures

Electronic properties of heterostructures in which a finite number of Mott-insulator layers are sandwiched by semi-infinite metallic leads are investigated by using the dynamical-mean-field method combined with the Keldysh Green's function technique to account for the finite bias voltage between the leads. Current across the junction is computed as a function of bias voltage. Electron spectral functions in the interacting region are shown to evolve by an applied bias voltage. This effect is measurable by photoemission spectroscopy and scanning tunneling microscopy. Further predictions are made for the optical conductivity under a bias voltage as a possible tool to detect a deformed density of states. A general discussion of correlated-electron based heterostructures and future prospect is given.

Electronic properties of strained heterostructures

We present a theoretical study of the electronic properties of hetero structures composed of strained layers sandwiched between two identical semiconductors. The electronic structure is calculated by using the theory of interface response functions within the frame of a two band model which provides a reasonable description of the bulk electronic structure of the host materials. This theory is then applied to the heterostructures AlSb/GaSb/AlSb, InAr/GaSb/InAs. and GaSb/InAs/GaSb. In our model, the strains are due to weakly-lattice mismatched materials. The evolution of the electronic structure is examined in function of the interfacial strains and of the sandwiched layer thickness