ELECTRONIC STRUCTURE AND OPTICAL ABSORPTION OF N-DOPED ZnO

2009 ◽  
Vol 23 (27) ◽  
pp. 3243-3251 ◽  
Author(s):  
MEILI GUO ◽  
X. D. ZHANG
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Valence Band ◽  
Density Functional ◽  
Optical Band Gap ◽  
Optical Transition ◽  
Low Energy ◽  
Functional Theory ◽  
N Doping ◽  
Doped Zno

The plane-wave pseudopotential method, based on density functional theory (DFT), has been used to calculate the electronic and optical properties of pure ZnO and N-doped ZnO . The results of density of states (DOS) indicate that the band gap of N-doped ZnO decreases due to the increase of p states in the valence band. Meanwhile, the results of the imaginary part of dielectric function ε2(ω) reveal that the optical transition between O 2p states in the highest valence band and Zn 4s states in the lowest conduction band shifts to the low energy range due to N doping. The optical band gap of ZnO decreases from 3.2 to 2.2 eV after N doping.

Density functional theory calculations for the investigation of (Ag, N) codoping effect on the electronic and optical properties of anatase TiO2

2014 ◽  
Vol 28 (18) ◽  
pp. 1450112 ◽  
Author(s):  
Matiullah Khan ◽  
Wenbin Cao ◽  
Jing Li ◽  
Muhammad Iqbal Zaman ◽  
Abdul Manan
Keyword(s):  
Density Functional Theory ◽  
Visible Light ◽  
Band Gap ◽  
Light Absorption ◽  
Density Functional ◽  
Energy Calculation ◽  
Functional Theory ◽  
Visible Light Absorption ◽  
Defect Pair ◽  
N Doping

Efficient absorption of light in visible range and enhance separation of photoexcited electron-hole pairs (EHPs) are crucial for improving the photoactivity of metal nonmetal codoped TiO 2. By using density functional theory (DFT) calculations, an effective metal ( Ag ) and nonmetal ( N ) codoping approach is described to modify the photoelectrochemical properties of titanium dioxide ( TiO 2). Nitrogen (N) doping introduces isolated N -2p states above the valence band maximum (VBM) which acts as an electron trap to promote EHP recombination. For Ag -doped TiO 2, Ag -4d states are introduced above the VBM which leads to the band gap narrowing. Silver (Ag) and nitrogen codoped TiO 2 possess stable configuration, narrowed band gap and best visible light absorption. Defect pair binding energy calculation shows that individual dopants, located at a distance of 8.951 Å bind each other, which indicates that the defect pair is stable compared to the isolated impurities in the host lattice. Ag and N codoped TiO 2 shows better visible light absorption as compared to other doped models due to the reduced band gap. N doping reduces the band gap of TiO 2 while Ag doping enhances the EHPs separation, so their combined presence in a sample would improve the photocatalytic activity due to their synergistic codoping effect. Our calculations provide reasonable explanation for the experimental findings.

Electronic Structures of Antisite Defects in Chiral (6,2) SiC Nanotubes

2016 ◽  
Vol 873 ◽  
pp. 38-42
Author(s):  
Hu Shan Ma ◽  
Hong Xia Liu ◽  
Ke Jian Li
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Valence Band ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Antisite Defect ◽  
Functional Theory ◽  
Antisite Defects ◽  
Occupied Level

Antisite defects are common defects in nanotube materials and have seriously impacts on their electronic properties. Based on density-functional theory calculations, the electronic structures of the antisite defective chiral (6, 2) SiCNTs are investigated. C antisite and Si antisite lead to the formation of a depression and a bump in the surface of the nanotube, respectively. In the band gap of the SiCNT with a C antisite defect, the occupied level near the top of the valence band is formed, while the unoccupied level originating from the Si antisite defect enters the conduction band of the SiCNT.

Effect of Al Excess on the Band Structure of ZnO Using Density Functional Theory

2016 ◽  
Vol 857 ◽  
pp. 106-110
Author(s):  
J.H. Lim ◽  
Cheow Keat Yeoh ◽  
Abdullah Chik ◽  
Pei Leng Teh
Keyword(s):  
Electrical Conductivity ◽  
Density Functional Theory ◽  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Band Structure Calculation ◽  
Al Doping ◽  
Electronic Band ◽  
Functional Theory ◽  
Doped Zno

The effect of Al doping to the band structure of ZnO was studied in this paper. The electronic band structure of Al doped ZnO was determined by using first-principles based on density functional theory. ABINIT was used to perform the band structure calculation. The calculated band structure of ZnO and Al doped ZnO shows that ZnO is a direct band gap semiconductor. The band structure become narrow with Al doping compared pure ZnO. With Al doping, the band gap of ZnO (0.749 eV) become smaller as the concentration Al doping increased to 4wt% (0.551 eV). The electrical conductivity of Al doped ZnO was studied as a references value for the band gap. The electrical conductivity of ZnO (8.21 S/cm) was enhanced with Al doping increased to 4wt% (71.87 S/cm).

Electronic Properties of Doped Wurtzite ZnO: Density Functional Theory

2020 ◽  
Vol 65 (3) ◽  
pp. 268 ◽  
Author(s):  
Jamal A. Talla
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Nitrogen Concentration ◽  
Functional Theory ◽  
Nitrogen Doped ◽  
The Density Functional Theory ◽  
Hubbard U ◽  
Doped Zno

We implemented the density functional theory to inspect the electronic properties of pristine and nitrogen-doped wurtzite ZnO. We use the Hubbard U (DFT + Ud + Up) method to correct any underestimation in the band gap. The obtained band gap is consistent with previous experimental results. Here, we consider four different configurations of nitrogen-doped ZnO. We have found that the band gap values for ZnO are sensitive to the nitrogen concentration.

scholarly journals Complex magnetism of the two-dimensional antiferromagnetic Ge2F: from a Néel spin-texture to a potential antiferromagnetic skyrmion

RSC Advances ◽  
2021 ◽  
Vol 11 (15) ◽  
pp. 8654-8663
Author(s):  
Fatima Zahra Ramadan ◽  
Flaviano José dos Santos ◽  
Lalla Btissam Drissi ◽  
Samir Lounis
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Density Functional ◽  
Low Energy ◽  
Two Dimensional ◽  
Functional Theory ◽  
2D Material ◽  
Energy Models ◽  
Spin Texture

Based on density functional theory combined with low-energy models, we explore the magnetic properties of a hybrid atomic-thick two-dimensional (2D) material made of germanene doped with fluorine atoms in a half-fluorinated configuration (Ge2F).

A New Approach for Calculating the Band Gap of Semiconductors within the Density Functional Method

2015 ◽  
Vol 242 ◽  
pp. 434-439 ◽  
Author(s):  
Vasilii E. Gusakov
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Localized States ◽  
Experimental Accuracy ◽  
Functional Theory ◽  
New Approach ◽  
The Density Functional Theory

Within the framework of the density functional theory, the method was developed to calculate the band gap of semiconductors. We have evaluated the band gap for a number of monoatomic and diatomic semiconductors (Sn, Ge, Si, SiC, GaN, C, BN, AlN). The method gives the band gap of almost experimental accuracy. An important point is the fact that the developed method can be used to calculate both localized states (energy deep levels of defects in crystal), and electronic properties of nanostructures.

Understanding the advantage of hexagonal WO3 as an efficient photoanode for solar water splitting: a first-principles perspective

2016 ◽  
Vol 4 (29) ◽  
pp. 11498-11506 ◽  
Author(s):  
Taehun Lee ◽  
Yonghyuk Lee ◽  
Woosun Jang ◽  
Aloysius Soon
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Water Splitting ◽  
Anode Material ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Good Alternative ◽  
Functional Theory ◽  
Solar Water Splitting

Using first-principles density-functional theory calculations, we investigate the advantage of using h-WO3 (and its surfaces) over the larger band gap γ-WO3 phase for the anode in water splitting. We demonstrate that h-WO3 is a good alternative anode material for optimal water splitting efficiencies.

scholarly journals Study of Pb ion adsorption on (n, 0) CNTs (n=4, 5, 6)

2018 ◽  
Vol 7 (6) ◽  
pp. 469-473 ◽  
Author(s):  
Wei Li ◽  
Yun Zhao ◽  
Teng Wang
Keyword(s):  
Density Functional Theory ◽  
Carbon Nanotube ◽  
Band Gap ◽  
Density Functional ◽  
Ion Adsorption ◽  
Chemical Adsorption ◽  
Adsorption Ability ◽  
Single Vacancy ◽  
Functional Theory ◽  
Before And After

AbstractAbsorption of Pb ion on the (n, 0) carbon nanotube (CNT) (n=4, 5, 6) surface, pure and defected with single vacancy, is investigated based on density functional theory. Pristine (n, 0) CNTs can produce a certain degree of chemical adsorption of Pb ion. While a single vacancy is introduced, the adsorption ability of CNTs for Pb ion increases greatly, and the band gap changes significantly before and after adsorption. SV-(6, 0) CNTs have the strongest adsorption ability, and SV-(5, 0) CNTs are the potential material for the Pb ion detection sensor. It is expected that these could be helpful to the design of Pb filters and sensors.

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