A First-Principles Study on Electronic Properties of Ce/N Codoped Anatase TiO2

Density function theory is performed in order to investigate the effect of Ce/N co-doping on geometry structure, electronic and optical properties of anatase TiO2. Comparing the energy band and density of states of pure TiO2 and Ce/N doped anatase TiO2. We can conclude that, the valence band of pure TiO2 is main composed of O 2p states and the conduction is mainly composed of Ti 3d states. For N-doped TiO2, the topmost part of the valence band is mainly occupied by N 2p states which is higher than that of the O 2p states which can narrowed the band gap. Ce doping will introduce 4f states which is involved in the conduction band. These may lead the conduction band move down. As for Ce and N co-doped, the top of the valence band is mainly occupied by an admixture N 2p, O 2p and the bottom of the conduction band is predominantly occupied by an admixture of Ce 4f ,Ti 3d. The strong interaction between the dopants and the ions lead the band gap get narrower. We predict that Ce+N doping is one of the best choices for enhancing the photoelectrochemical activity of TiO2.

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THE EFFECT OF HIGH N-DOPED ANATASE TiO2 ON THE BAND GAP NARROWING AND REDSHIFT BY FIRST-PRINCIPLES

Modern Physics Letters B ◽

10.1142/s0217984912501795 ◽

2012 ◽

Vol 26 (27) ◽

pp. 1250179 ◽

Cited By ~ 4

Author(s):

QINGYU HOU ◽

YONGJUN JIN ◽

CHUN YING ◽

ERJUN ZHAO ◽

YUE ZHANG ◽

...

Keyword(s):

Band Gap ◽

First Principles ◽

Formation Energy ◽

Doping Concentration ◽

Covalent Bond ◽

Anatase Tio2 ◽

Structure Population ◽

Densities Of States ◽

N Doping ◽

Band Gap Narrowing

Anatase TiO 2 supercells were studied by first-principles, in which one was undoped and another three were high N -doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO 2-x N x (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N -doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.

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The Electronic and Structural Properties of 3C-SiC: A First-Principles Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.971-973.208 ◽

2014 ◽

Vol 971-973 ◽

pp. 208-212 ◽

Cited By ~ 1

Author(s):

Ying Gao ◽

Fu Chun Zhang ◽

Wei Hu Zhang

Keyword(s):

Band Gap ◽

Valence Band ◽

Conduction Band ◽

First Principles ◽

Density Functional ◽

Energy Splitting ◽

Functional Theory ◽

Structure Density ◽

Indirect Band Gap ◽

Electronic And Structural Properties

We investigate geometric structure, electronic structure and ground properties of 3C-SiC as obtained form first-principles calculations based on density functional theory with the LDA, GGA, B3LYP and HSE06 method. After comparative analysis of the total energy, band structure, density of states and the bulk modulus, we found that 3C-SiC was an indirect band gap semiconductor, the top of valence band was located at Γ point, and the bottom of conduction band was located at X point. The indirect band gap of 3C-SiC calculated by LDA, GGA, B3LYP and HSE06 was 1.34 eV, 1.44 eV, 2.88 eV and 2.26 eV, respectively. Especially for B3LYP and HSE06 methods which clearly calculated the energy splitting and the energy dispersion of both the top of valence band and the bottom of conduction band was in well agreement with the experimental data. These results will provide theoretical basis for the design and application of SiC materials.

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First-Principles Calculations on the Electronic Structure of ZnO Nanowires

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.198-199.23 ◽

2012 ◽

Vol 198-199 ◽

pp. 23-27

Author(s):

Nan Zhang ◽

Hong Sheng Zhao ◽

Dong Yang ◽

Wen Jie Yan

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Valence Band ◽

Conduction Band ◽

First Principles ◽

Density Functional ◽

Valence Band Maximum ◽

Zno Nanowires ◽

Cross Sectional ◽

Quantum Size

Based upon the density functional theory (DFT) in this paper, the first-principles approach is used to study the electronic structure of different cross-sectional diameters of ZnO [0001] nanowires of wurtzite structure. The results show that ZnO [0001] nanowires have a wide direct band gap. Located in the G-point of the Brillouin zone the conduction band minimum and valence band maximum are relatively smooth. The conduction band is mainly composed of Zn 4s and Zn 4p states, and the valence band is composed of Zn 3d and O 2p states. The effective mass of conduction band electrons and valence band holes are large while their mobility is very low which show that conductive ability of pure defect-free [0001] ZnO nanowires is weak. Along with the increase of the cross-sectional diameters, the band gap gradually decreases that indicates quantum size effects are obvious in the nano size range.

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First principles study of electronic structures of dopants in Mg2Si

MRS Proceedings ◽

10.1557/opl.2011.1239 ◽

2011 ◽

Vol 1329 ◽

Cited By ~ 2

Author(s):

K. Xiong ◽

S. Sobhani ◽

R. P. Gupta ◽

W. Wang ◽

B. E. Gnade ◽

...

Keyword(s):

Band Gap ◽

Valence Band ◽

Conduction Band ◽

Density Of States ◽

First Principles ◽

Band Edge ◽

Conduction Band Edge ◽

Hybrid Functional ◽

Thermoelectric Efficiency ◽

The Impact

ABSTRACTWe investigate the impact of various dopants (Na, Ag, Cd, Zn, Al, Ga, In, Tl, Ge, and Sn) on the electronic structure of Mg2Si by first principles calculations using a hybrid functional that does not need a band gap correction. We find that for Na and Ge in Mg2Si, the impurity-induced states do not affect the density of states at both edges of the valence band and the conduction band. Ag- and Sn affect slightly the density of states at the valence band edge, while Cd and Zn affect slightly the density of state at the conduction band edge. Al and In could modify significantly the density of states at the conduction band edge. Ga introduces states just at the bottom of the conduction band. Tl introduces states in the band gap. This study provides useful information on optimizing the thermoelectric efficiency of Mg2Si.

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A first-principles study of anionic (S) and cationic (V/Nb) doped Sr2Ta2O7 for visible light photocatalysis

RSC Advances ◽

10.1039/c7ra07113b ◽

2017 ◽

Vol 7 (65) ◽

pp. 40922-40928 ◽

Cited By ~ 3

Author(s):

Yuman Peng ◽

Zuju Ma ◽

Junjie Hu ◽

Kechen Wu

Keyword(s):

Visible Light ◽

Valence Band ◽

Conduction Band ◽

First Principles ◽

Valence Band Maximum ◽

Conduction Band Minimum ◽

Visible Light Photocatalysis ◽

Band Maximum ◽

Co Doping ◽

First Principles Study

In order to utilize the visible light to catalyze water, UV-active Sr2Ta2O7 is engineered via co-doping of S and V/Nb to shift the valence band maximum upward and conduction band minimum downward by approximately 1 eV, respectively.

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N-doping induced band-gap reduction in III-V semiconductors: First-principles calculations

physica status solidi (c) ◽

10.1002/pssc.201000578 ◽

2011 ◽

Vol 8 (2) ◽

pp. 352-355 ◽

Cited By ~ 1

Author(s):

Masato Ishikawa ◽

Takashi Nakayama

Keyword(s):

Band Gap ◽

First Principles ◽

First Principles Calculations ◽

N Doping

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BORON/PHOSPHORUS CO-DOPING IN ZIGZAG SINGLE-WALLED CARBON NANOTUBES: A FIRST-PRINCIPLES STUDY

Modern Physics Letters B ◽

10.1142/s0217984913501145 ◽

2013 ◽

Vol 27 (15) ◽

pp. 1350114

Author(s):

FUSHENG LUO ◽

QINGYI SHAO ◽

LIXIA ZHANG ◽

JUAN ZHANG ◽

ZHONGLIANG PAN

Keyword(s):

Carbon Nanotubes ◽

First Principles ◽

Function Theory ◽

Energy Gap ◽

Single Walled Carbon Nanotubes ◽

Band Structures ◽

Single Walled Carbon ◽

Co Doping ◽

Walled Carbon Nanotubes ◽

Formation Energies

By using the first-principles methods based on density function theory (DFT), the effects of boron(B)/phosphorus(P) pair co-doping on the electrical properties of zigzag single-walled carbon nanotubes (SWNTs) have been investigated. We calculated the formation energies and band structures of (6, 0) metallic and (8, 0) semiconducting SWNTs with different B/P co-doping sites and concentrations. The obtained formation energies suggest that the B/P co-doping configurations are energetically stable structures and the B and P tend to form a B–P bond. It shows that an energy gap is opened by B/P co-doping in (6, 0) metallic SWNTs and the metallic carbon nanotubes are converted into semiconductors. For the (8, 0) semiconducting SWNTs, B/P co-doping influences the band structure, but it does not change the attributes essentially and the SWNTs are still semiconducting. It was also found that the band structures depend on the doping concentration as well as the doping site of B/P pair.

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Effects of Substrate Orientation on the Valence Band Splittings and Valence Band Offsets in GaN and AlN Films

MRS Proceedings ◽

10.1557/proc-482-917 ◽

1997 ◽

Vol 482 ◽

Cited By ~ 3

Author(s):

J. A. Majewski ◽

M. Städele

Keyword(s):

Valence Band ◽

Conduction Band ◽

First Principles ◽

Stacking Fault ◽

Type I ◽

Band Offsets ◽

Substrate Orientation ◽

First Principles Study

AbstractWe present a first-principles study of heteroepitaxial interfaces between GaN and both cubic as well as wurtzite AlN substrates oriented along main cubic or hexagonal directions and of stacking fault interfaces between cubic and wurtzite GaN. Our calculations show that all studied heterostructures are of type I. Valence band offsets for GaN/AlN are nearly independent of the substrate orientation and of the order of 0.8 eV. The valence and conduction band offsets for a stacking fault interface are predicted to be 40 meV and 175 meV, respectively.

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LITAO3 CHARACTERIZATION OF RUBIDIUM ON TEMPERATURE VARIATIONS

Journal of Science Innovare ◽

10.33751/jsi.v1i02.1005 ◽

2018 ◽

Vol 1 (02) ◽

pp. 54-59

Author(s):

Agus Ismangil ◽

Teguh Puja Negara

Keyword(s):

Band Gap ◽

Valence Band ◽

Conduction Band ◽

Transmission Rate ◽

Ferroelectric Material ◽

Band Gap Energy ◽

Ferroelectric Materials ◽

Annealing Process ◽

Optical Modulators ◽

Gap Energy

One of the studies that recently attracted the attention of physicists is research on ferroelectric material because this material is very promising for the development of new generation devices in connection with the unique properties it has. Ferroelectric materials, especially those based on a mixture of lithium tantalite (LiTaO3), are expected to be applied to the infrared sensor. Lithium tantalate (LiTaO3) is a ferroelectric material that is unique in terms of pyroelectric and piezoelectric properties that are integrated with good mechanical and chemical stability. Therefore LiTaO3 is often used for several applications such as electro-optical modulators and pyroelectric detectors. LiTaO3 is a non-hygroscopic crystal, colorless, soluble in water, has a high transmission rate and does not easily damage its optical properties. LiTaO3 is a material that has a high dielectric constant and a high load storage capacity. This research has succeeded in determining the band gap energy of the LiTaO3 film in the rubidium chamber obtained in the range of values 2.02-2.98 eV as shown in figure 4. The LiTaO3 film after the annealing process at a temperature of 650 oC, has the highest band gap energy of 2.98 eV. Large energy is needed on the electrons to be excited from the valence band to the conduction band. Whereas in the LiTaO3 film after an annealing process of 800 oC, the band gap energy obtained is 2.02 eV. This makes it easier for electrons to be excited from the valence band to the conduction band because the energy needed is not too large.

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