scholarly journals Tunable Electronic Properties of Type-II SiS2/WSe2 Hetero-Bilayers

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2037
Author(s):  
Yue Guan ◽  
Xiaodan Li ◽  
Ruixia Niu ◽  
Ningxia Zhang ◽  
Taotao Hu ◽  
...  
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Photogenerated Electron ◽  
Strain Range ◽  
Band Alignment ◽  
Type Ii ◽  
Electron Hole ◽  
Structural And Electronic Properties ◽  
Indirect Band Gap

First-principle calculations based on the density functional theory (DFT) are implemented to study the structural and electronic properties of the SiS2/WSe2 hetero-bilayers. It is found that the AB-2 stacking model is most stable among all the six SiS2/WSe2 heterostructures considered in this work. The AB-2 stacking SiS2/WSe2 hetero-bilayer possesses a type-II band alignment with a narrow indirect band gap (0.154 eV and 0.738 eV obtained by GGA-PBE and HSE06, respectively), which can effectively separate the photogenerated electron–hole pairs and prevent the recombination of the electron–hole pairs. Our results revealed that the band gap can be tuned effectively within the range of elastic deformation (biaxial strain range from −7% to 7%) while maintaining the type-II band alignment. Furthermore, due to the effective regulation of interlayer charge transfer, the band gap along with the band offset of the SiS2/WSe2 heterostructure can also be modulated effectively by applying a vertical external electric field. Our results offer interesting alternatives for the engineering of two-dimensional material-based optoelectronic nanodevices.

scholarly journals Structural and Electronic Properties of Heterostructures Composed of Antimonene and Monolayer MoS2

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2358
Author(s):  
Congcong Zhou ◽  
Xiaodan Li ◽  
Taotao Hu
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Van Der Waals ◽  
Broad Band ◽  
Photogenerated Electron ◽  
Band Alignment ◽  
Monolayer Mos2 ◽  
Photoelectric Properties ◽  
Structural And Electronic Properties

Antimonene is found to be a promising material for two-dimensional optoelectronic equipment due to its broad band gap and high carrier mobility. The van der Waals heterostructure, as a unique structural unit for the study of photoelectric properties, has attracted great attention. By using ab initio density functional theory with van der Waals corrections, we theoretically investigated the structural and electronic properties of the heterostructures composed of antimonene and monolayer MoS2. Our results revealed that the Sb/MoS2 hetero-bilayer is an indirect semiconductor with type-II band alignment, which implies the spatial separation of photogenerated electron–hole pairs. Due to the weak van der Waals interlayer interactions between the adjacent sheets of the hetero-bilayer systems, the band structures of isolated antimonene and monolayer MoS2 are preserved. In addition, a tunable band gap in Sb/MoS2 hetero-bilayer can be realized by applying in-plane biaxial compressing/stretching. When antimonene and monolayer MoS2 are stacked into superlattices, the indirect semiconductors turn into direct semiconductors with the decreased band gaps. Our results show that the antimonene-based hybrid structures are good candidate structures for photovoltaic devices.

Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

2007 ◽  
Vol 996 ◽  
Author(s):  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Oxygen Vacancy ◽  
Optical Absorption ◽  
Total Energy ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural And Electronic Properties ◽  
Defect Levels ◽  
Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

scholarly journals Organically interconnected graphene flakes: A flexible 3-D material with tunable electronic bandgap

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. Klontzas ◽  
E. Tylianakis ◽  
V. Varshney ◽  
A. K. Roy ◽  
G. E. Froudakis
Keyword(s):  
Chemical Composition ◽  
Band Gap ◽  
Electronic Properties ◽  
Flexible Electronics ◽  
Density Functional ◽  
Organic Molecule ◽  
Tight Binding ◽  
Structural And Electronic Properties ◽  
Graphene Flakes ◽  
Band Gap Tuning

Abstract The structural and electronic properties of molecularly pillared graphene sheets were explored by performing Density Functional based Tight Binding calculations. Several different architectures were generated by varying the density of the pillars, the chemical composition of the organic molecule acting as a pillar and the pillar distribution. Our results show that by changing the pillars density and distribution we can tune the band gap transforming graphene from metallic to semiconducting in a continuous way. In addition, the chemical composition of the pillars affects the band gap in a lesser extent by introducing additional states in the valence or the conduction band and can act as a fine band gap tuning. These unique electronic properties controlled by design, makes Mollecular Pillared Graphene an excellent material for flexible electronics.

scholarly journals Electronic properties of the Sn1−xPbxO alloy and band alignment of the SnO/PbO system: a DFT study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. Kelaidis ◽  
S. Bousiadi ◽  
M. Zervos ◽  
A. Chroneos ◽  
N. N. Lathiotakis
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Hydrogen Generation ◽  
Valence Band Maximum ◽  
Oxide System ◽  
Band Alignment ◽  
Oxide Thin Film ◽  
Ternary Oxide ◽  
P Type

Abstract Tin monoxide (SnO) has attracted attention due to its p-type character and capability of ambipolar conductivity when properly doped, properties that are beneficial for the realization of complementary oxide thin film transistors technology, transparent flexible circuits and optoelectronic applications in general. However, its small fundamental band gap (0.7 eV) limits its applications as a solar energy material, therefore tuning its electronic properties is necessary for optimal performance. In this work, we use density functional theory (DFT) calculations to examine the electronic properties of the Sn1−xPbxO ternary oxide system. Alloying with Pb by element substitution increases the band gap of SnO without inducing defect states in the band gap retaining the anti-bonding character of the valence band maximum which is beneficial for p-type conductivity. We also examine the properties of the SnO/PbO heterojunction system in terms of band alignment and the effect of the most common intrinsic defects. A broken gap band alignment for the SnO/PbO heterojunction is calculated, which can be attractive for energy conversion in solar cells, photocatalysis and hydrogen generation.

scholarly journals Tunable spin-polarized band gap in Si2/NiI2 vdW heterostructure

RSC Advances ◽  
2020 ◽  
Vol 10 (15) ◽  
pp. 8927-8935 ◽  
Author(s):  
Douglas Duarte de Vargas ◽  
Rogério José Baierle
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Van Der Waals ◽  
Functional Theory ◽  
Spin Polarized ◽  
Structural And Electronic Properties ◽  
Vdw Heterostructure

Using density functional theory (DFT) calculations we investigate the structural and electronic properties of a heterogeneous van der Waals (vdW) structure consisting of silicene and NiI2 single layers.

Density Functional Theory (DFT) Study: Electronic Properties of Silicene under Uniaxial Strain as H2S Gas Sensor

2016 ◽  
Vol 675-676 ◽  
pp. 15-18 ◽  
Author(s):  
Sasfan Arman Wella ◽  
Irfan Dwi Aditya ◽  
Triati Dewi Kencana Wungu ◽  
Suprijadi
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Band Gap Energy ◽  
Engineering Strain ◽  
Functional Theory ◽  
First Principle Calculation ◽  
Gap Energy ◽  
Center Configuration ◽  
Structural And Electronic Properties

First principle calculation is performed to investigate structural and electronic properties of strained silicene (silicon analogue of graphene) when absorbing the hydrogen sulfide molecule gas. Two configuration of silicene-H2S system, center and hollow configuration, is checked under 0% (pure), 5%, and 10% uniaxial engineering strain. We report that the silicene-H2S system in center configuration has larger binding energy compare to the silicene-H2S system in hollow configuration. The results show that H2S is physisorbed on silicene. In this work, we also find the change of band gap energy (~60 meV) is appearing when H2S interacted with silicene in center configuration, whereas the band gap energy of silicene has no change when interacted with H2S in hollow configuration.

scholarly journals Tunable Electronic Properties of Lateral Monolayer Transition Metal Dichalcogenide Superlattice Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 534
Author(s):  
Jinhua Wang ◽  
Gyaneshwar P. Srivastava
Keyword(s):  
Transition Metal ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Valence Band Maximum ◽  
Impurity Level ◽  
Asymmetric Structure ◽  
Transition Metal Dichalcogenide ◽  
Structural And Electronic Properties ◽  
Gap States

The structural stability and structural and electronic properties of lateral monolayer transition metal chalcogenide superlattice zigzag and armchair nanoribbons have been studied by employing a first-principles method based on the density functional theory. The main focus is to study the effects of varying the width and periodicity of nanoribbon, varying cationic and anionic elements of superlattice parent compounds, biaxial strain, and nanoribbon edge passivation with different elements. The band gap opens up when the (MoS2)3/(WS2)3 and (MoS2)3/(MoTe2)3 armchair nanoribbons are passivated by H, S and O atoms. The H and O co-passivated (MoS2)3/(WS2)3 armchair nanoribbon exhibits higher energy band gap. The band gap with the edge S vacancy connecting to the W atom is much smaller than the S vacancy connecting to the Mo atom. Small band gaps are obtained for both edge and inside Mo vacancies. There is a clear difference in the band gap states between inside and edge Mo vacancies for symmetric nanoribbon structure, while there is only a slight difference for asymmetric structure. The electronic orbitals of atoms around Mo vacancy play an important role in determining the valence band maximum, conduction band minimum, and impurity level in the band gap.

scholarly journals Strain Induced Tunability of the Electronic Properties of SrTiO3 Interfaces

2019 ◽  
Author(s):  
Zhenyun Lan ◽  
Tejs Vegge ◽  
Ivano E. Castelli
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Axial Strain ◽  
Compressive Strain ◽  
Conduction Band Edge ◽  
Biaxial Strain ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
New Perspective

SrTiO 3 (STO) films are widely used as substrates in oxide devices. Although STO is one of the most studied materials, both experimentally and computationally, the effect of strain at the interface is almost completely ignored. In this work, we perform Density Functional Theory (DFT) calculations using the SCAN meta-GGA exchange-correlation functional to study the effect of uniaxial- and biaxial-strain on structural and electronic properties of STO interfaces. We find that under tensile uniaxial-strain, the band gap increases significantly, as a consequence of a large tilting in the octahedra. On the other side, under compression, the band gap is almost constant. Similar effects are seen for tensile biaxial strain, while for compressive strain, the gap first increases and then decreases, due to the temporary appearance of a polar distortion. In addition, we observe an orbital inversion at the conduction-band edge under different uni/bi-axial-strain conditions. This work provides a new perspective of the use of strain to modulate the structural and electronic properties of perovskite film materials for multiple applications.

scholarly journals Strain Induced Tunability of the Electronic Properties of SrTiO3 Interfaces

2019 ◽  
Author(s):  
Zhenyun Lan ◽  
Tejs Vegge ◽  
Ivano E. Castelli
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Axial Strain ◽  
Compressive Strain ◽  
Conduction Band Edge ◽  
Biaxial Strain ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
New Perspective

SrTiO 3 (STO) films are widely used as substrates in oxide devices. Although STO is one of the most studied materials, both experimentally and computationally, the effect of strain at the interface is almost completely ignored. In this work, we perform Density Functional Theory (DFT) calculations using the SCAN meta-GGA exchange-correlation functional to study the effect of uniaxial- and biaxial-strain on structural and electronic properties of STO interfaces. We find that under tensile uniaxial-strain, the band gap increases significantly, as a consequence of a large tilting in the octahedra. On the other side, under compression, the band gap is almost constant. Similar effects are seen for tensile biaxial strain, while for compressive strain, the gap first increases and then decreases, due to the temporary appearance of a polar distortion. In addition, we observe an orbital inversion at the conduction-band edge under different uni/bi-axial-strain conditions. This work provides a new perspective of the use of strain to modulate the structural and electronic properties of perovskite film materials for multiple applications.

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