Surface Passivation Effect of Hydrogen and Methyl on the Structural and Electronic Properties of Silicon Quantum Dots: Density Functional Calculation

2016 ◽  
Vol 846 ◽  
pp. 375-382 ◽  
Author(s):  
Muhammad Mus-'ab Anas ◽  
Geri Gopir
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Surface Passivation ◽  
Geometry Optimization ◽  
Point Of View ◽  
Silicon Quantum Dots ◽  
Radiative Relaxation ◽  
Structural And Electronic Properties

We have carried out a series of DFT calculations to investigate changes on the structural and electronic properties of Silicon (Si) quantum dots as a function of surface passivation. In particular, we have study non-polar passivation effect of hydrogen (H) and methyl (CH3) at the surface of quantum dots. From geometry optimization result, we find that clusters with reconstructed surfaces a complete methyl passivation is possible and steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. On the electronic properties point of view, it is noticed for small nanocrystals, the presence of mini-gaps are more pronounced which can limit the non-radiative relaxation of excitons. Obviously, methyl passivation weakly affects the band gap values of silicon quantum dots, while it substantially decreases the band gap and reduce mini-gap appearance compared to hydrogen passivation Si QDs. On the basis of our results we propose that methyl terminated quantum dots may be size selected taking advantage of the reduction on mini-gap and the localization of electron as a function of the cluster size.

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.

Can inorganic salts tune electronic properties of graphene quantum dots?

2015 ◽  
Vol 17 (26) ◽  
pp. 17413-17420 ◽  
Author(s):  
Guilherme Colherinhas ◽  
Eudes Eterno Fileti ◽  
Vitaly V. Chaban
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Graphene Quantum Dots ◽  
Inorganic Salts ◽  
Ionic Clusters ◽  
Functional Theory ◽  
Free Ions

In this work, we apply density functional theory to study the effect of neutral ionic clusters adsorbed on the GQD surface. We conclude that both the HOMO and the LUMO of GQDs are very sensitive to the presence of ions and to their distance from the GQD surface. However, the alteration of the band gap itself is modest, as opposed to the case of free ions (recent reports). Our work fosters progress in modulating electronic properties of nanoscale carbonaceous materials.

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.

Theoretical Study on Structural and Electronic Properties of EDOT:SS Oligomers Complex

2015 ◽  
Vol 1131 ◽  
pp. 123-127
Author(s):  
Ampaiwan Marutaphan ◽  
Panida Lorwongtragool ◽  
Chatchawal Wongchoosuk
Keyword(s):  
Electronic Properties ◽  
Polymer Chain ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Average Distance ◽  
Geometry Optimization ◽  
Am1 Method ◽  
Structural And Electronic Properties ◽  
Binding Distance

In this paper, we have reported a theoretical study of the geometric and electronic structures of EDOT:SS oligomers based on semi-empirical Austin model1 (AM1) method and density functional theory at B3LYP/3-21G* level. The effects of polymer chain length of both EDOT and SS on structural and electronic properties including bond length, bond angle, binding distance, charge, the highest occupied orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and energy gap have been studied from the optimized oligomers which were built by varying repeating unit of monomer as n = 1, 2, 3 and 4. The results show that AM1 is not appropriate for geometry optimization of EDOT:SS system comparing to B3LYP/3-21G* level. The binding distance between H atom on EDOT and O atom on SS tends to close together with the average distance of 2.21 Å. The most positive charges locate at sulfur atoms on EDOT and EDOT:SS. The electrical conductivity of EDOT, SS and EDOT:SS increases when polymer chain is extended.

Insight into the effects of surface oxidation and carbonization on the electronic properties of silicon quantum dots and silicon slabs: a density functional study

RSC Advances ◽  
2014 ◽  
Vol 4 (105) ◽  
pp. 60948-60952 ◽  
Author(s):  
Yuheng Zeng ◽  
Liang Chen ◽  
Guoqiang Liu ◽  
Hua Xu ◽  
Weijie Song
Keyword(s):  
Quantum Dots ◽  
Electronic Properties ◽  
Density Functional ◽  
Surface Oxidation ◽  
Functional Study ◽  
Silicon Quantum Dots ◽  
Carrier Recombination ◽  
Oxygen Oxidation ◽  
Si Quantum Dots ◽  
Insight Into

In this work, we investigated the effects of surface backbond-oxygen oxidation and surface substitute-carbon carbonization on carrier recombination and transportation of 10-, 12- and 14 Å Si quantum dots (QDs).

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.

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