Analysis of electronic structure and optical properties of N-doped SiO2 based on DFT calculations

2015 ◽  
Vol 29 (19) ◽  
pp. 1550100 ◽  
Author(s):  
Sui-Shuan Zhang ◽  
Zong-Yan Zhao ◽  
Pei-Zhi Yang
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Impurity Concentration ◽  
Nitrogen Concentration ◽  
Energy Levels ◽  
Optical Parameter ◽  
Doping Effects ◽  
N Doping ◽  
The Relationship

The crystal structure, electronic structure and optical properties of N-doped [Formula: see text] with different N impurity concentrations were calculated by density function theory within GGA[Formula: see text]+[Formula: see text]U method. The crystal distortion, impurity formation energy, band gap, band width and optical parameter of N-doped [Formula: see text] are closely related with N impurity concentration. Based on the calculated results, there are three new impurity energy levels emerging in the band gap of N-doped [Formula: see text], which determine the electronic structure and optical properties. The variations of optical properties induced by N doping are predominately determined by the unsaturated impurity states, which are more obvious at higher N impurity concentration. In addition, all the doping effects of N in both [Formula: see text]-quartz [Formula: see text] and [Formula: see text]-quartz [Formula: see text] are very similar. According to these findings, one could understand the relationship between nitrogen concentration and optical parameter of [Formula: see text] materials, and design new optoelectrionic Si–O–N compounds.

Effects of N Concentration on Electronic Structure and Optical Absorption Properties of N-Doped SrTiO3 from First Principles

2013 ◽  
Vol 749 ◽  
pp. 561-568 ◽  
Author(s):  
Chao Zhang ◽  
Yong Zhong Jia ◽  
Yan Jing ◽  
Ying Yao ◽  
Jun Ma ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Doping Level ◽  
Density Functional ◽  
Energy Gap ◽  
Nitrogen Concentration ◽  
Band Structure Calculation ◽  
Concentration Effects ◽  
N Doping

The nitrogen concentration effects on electronic structures and optical properties of N-doped SrTiO3 have been investigated on the basis of density functional theory (DFT) calculations. Through band structure calculation, a direct band gap is predicted in SrTiO3-xNx. Electronic structure analysis shows that the doping N could substantially lower the band gap of SrTiO3 by the presence of an impurity state of N 2p on the upper edge of the valence band. When the doping level rises, the energy gap has little further narrowing compared with that at lower doping levels. The calculations of optical properties indicate a possible optimum N-doping level in SrTiO3 with a high photo response for visible light. These conclusions are in agreement with the recent experimental results.

Effects of N-doping concentration on the electronic structure and optical properties of N-doped β-Ga 2 O 3

2012 ◽  
Vol 21 (6) ◽  
pp. 067102 ◽  
Author(s):  
Li-Ying Zhang ◽  
Jin-Liang Yan ◽  
Yi-Jun Zhang ◽  
Ting Li
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Doping Concentration ◽  
N Doping

First-principles study on the doping effects of nitrogen on the electronic structure and optical properties of Cu2O

RSC Advances ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Zongyan Zhao ◽  
Xijia He ◽  
Juan Yi ◽  
Chenshuo Ma ◽  
Yuechan Cao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
First Principles Study ◽  
Doping Effects

Electronic Structure for a Distorted Chain

1972 ◽  
Vol 50 (11) ◽  
pp. 1078-1081
Author(s):  
T. C. Wong ◽  
B. Y. Tong
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Density Of States ◽  
Energy Levels ◽  
Linear Chain ◽  
Integrated Density Of States ◽  
Counting Method ◽  
Model Liquid ◽  
Impurity Atoms ◽  
Specific Manner

A linear chain with impurities randomly distributed along it is studied by means of the node counting method. The host atoms as well as the impurity atoms are represented by negative δ-function potentials with different strengths. The solvent atoms are distorted in a specific manner about each impurity atom. The integrated density of states are calculated near a band gap for different impurity concentrations and for various degrees of distortion. It was found that without distortion the gap remains practically structureless, whereas with distortion the energy levels diffuse into the gap. The results are qualitatively similar to that of a model liquid.

scholarly journals The Effect of Defect Disorder on the Electronic Structure of Rutile TiO2-x

2006 ◽  
Vol 251-252 ◽  
pp. 1-12 ◽  
Author(s):  
Faruque M. Hossain ◽  
Graeme E. Murch ◽  
L. Sheppard ◽  
Janusz Nowotny
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Point Defects ◽  
Density Functional ◽  
Defect Formation ◽  
Energy Levels ◽  
Defect Energy ◽  
Defect Disorder ◽  
Effect Of Oxygen ◽  
Formation Energies

The purpose of this work is to study the effect of bulk point defects on the electronic structure of rutile TiO2. The paper is focused on the effect of oxygen nonstoichiometry in the form of oxygen vacancies, Ti interstitials and Ti vacancies and related defect disorder on the band gap width and on the local energy levels inside the band gap. Ab initio density functional theory is used to calculate the formation energies of such intrinsic defects and to detect the positions of these defect induced energy levels in order to visualize the tendency of forming local mid-gap bands. Apart from the formation energy of the Ti vacancies (where experimental data do not exist) our calculated results of the defect formation energies are in fair agreement with the experimental results and the defect energy levels consistently support the experimental observations. The calculated results indicate that the exact position of defect energy levels depends on the estimated band gap and also the charge state of the point defects of TiO2.

Electronic structures and optical properties of cuprous oxide and hydroxide

2014 ◽  
Vol 1675 ◽  
pp. 185-190
Author(s):  
Yunguo Li ◽  
Cláudio M. Lousada ◽  
Pavel A. Korzhavyi
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Cuprous Oxide ◽  
Density Functional ◽  
Spent Nuclear Fuel ◽  
Energy Levels ◽  
Chemical Properties ◽  
Density Functional Theory Calculations ◽  
Hybrid Functional ◽  
Indirect Band Gap

ABSTRACTThe broad range of applications of copper, including areas such as electronics, fuel cells, and spent nuclear fuel disposal, require accurate description of the physical and chemical properties of copper compounds. Within some of these applications, cuprous hydroxide is a compound whose relevance has been recently discovered. Its existence in the solid-state form was recently reported. Experimental determination of its physical-chemical properties is challenging due to its instability and poop crystallinity. Within the framework of density functional theory calculations (DFT), we investigated the nature of bonding, electronic spectra, and optical properties of the cuprous oxide and cuprous hydroxide. It is found that the hybrid functional PBE0 can accurately describe the electronic structure and optical properties of these two copper(I) compounds. The calculated properties of cuprous oxide are in good agreement with the experimental data and other theoretical results. The structure of cuprous hydroxide can be deduced from that of cuprous oxide by substituting half Cu+ in Cu2O lattice with protons. Compared to Cu2O, the presence of hydrogen in CuOH has little effect on the ionic nature of Cu–O bonding, but lowers the energy levels of the occupied states. Thus, CuOH is calculated to have a wider indirect band gap of 2.73 eV compared with the Cu2O band gap of 2.17 eV.

scholarly journals First Principle Calculation of Electronic, Optical Properties and Photocatalytic Potential of CuO Surfaces

2016 ◽  
Vol 1 ◽  
Author(s):  
Faozan Ahmad
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Water Splitting ◽  
Co2 Reduction ◽  
Band Edge ◽  
Semiconductor Surface ◽  
First Principle Calculation ◽  
Stable Surface ◽  
Input Parameters

<p class="TTPKeywords">We have performed DFT calculations of electronic structure, optical properties and photocatalytic potential of the low-index surfaces of CuO. Photocatalytic reaction on the surface of semiconductor requires the appropriate band edge of the semiconductor surface to drive redox reactions. The calculation begins with the electronic structure of bulk system; it aims to determine realistic input parameters and band gap prediction. CuO is an antiferromagnetic material with strong electronic correlations, so that we have applied DFT + U calculation with spin polarized approach, beside it, we also have used GW approximation to get band gap correction. Based on the input parameters obtained, then we calculate surface energy, work function and band edge of the surfaces based on a framework developed by Bendavid et al (J. Phys. Chem. B, 117, 15750-15760) and then they are aligned with redox potential needed for water splitting and CO<sub>2</sub> reduction. Based on the calculations result can be concluded that not all of low-index CuO have appropriate band edge to push reaction of water splitting and CO2 reduction, only the surface CuO(111) and CuO(011) which meets the required band edge. Fortunately, based on the formation energy, CuO(111) and CuO(011) is the most stable surface. The last we calculate electronic structure and optical properties (dielectric function) of low-index surface of CuO, in order to determine the surface state of the most stable surface of CuO.</p>

DEEP LEVELS DUE TO VACANCY PAIRS IN SILICON

1989 ◽  
Vol 03 (06) ◽  
pp. 863-870 ◽  
Author(s):  
HONGQI XU ◽  
U. LINDEFELT
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
State Energy ◽  
Energy Levels ◽  
Mean Value ◽  
Deep Levels ◽  
Nearest Neighbour ◽  
Recursion Method ◽  
The Mean ◽  
The Many

The recursion method is used to investigate the electronic structure of undistorted vacancy pairs in silicon up to the seventh nearest-neighbour divacancy. The many energy levels associated with these vacancy pairs in and around the band gap region are calculated. The results of the calculation show that the strength of the interaction between a pair of vacancies depends as much on their relative positions as on the inter-vacancy distance, but the mean value of the gap-state energy levels remains essentially constant at the monovacancy level.

Electronic theoretical study on the influence of torsional deformation on the electronic structure and optical properties of BN-doped graphene

2018 ◽  
Vol 32 (16) ◽  
pp. 1850179
Author(s):  
Dazhi Fan ◽  
Guili Liu ◽  
Lin Wei
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Torsion Angle ◽  
Density Functional ◽  
Characteristic Peak ◽  
Torsional Deformation ◽  
Gap Opening ◽  
Doped Graphene ◽  
Medium Band

Based on the density functional theory, the effect of torsional deformation on the electronic structure and optical properties of boron nitride (BN)-doped graphene is studied by using the first-principles calculations. The band structure calculations show that the intrinsic graphene is a semi-metallic material with zero band gap and the torsional deformation has a large effect on its band gap, opening its band gap and turning it from the semi-metal to the medium band gap semiconductor. The doping of BN in graphene makes its band gap open and becomes a medium band gap semiconductor. When it is subjected to a torsional effect, it is found to have a weak influence on its band gap. In other words, the doping of BN makes the changes of the band gap of graphene no longer sensitive to torsional deformation. Optical properties show that the doping of BN leads to a significant decrease in the light absorption coefficient and reflectivity of the graphene at the characteristic peak and that of BN-doped graphene system is also weakened by torsional deformation at the characteristic peak. In the absorption spectrum, the absorption peaks of the doping system of the torsion angle of 2–20[Formula: see text] are redshifted compared with that of the BN-doped system (the torsion angle is 0[Formula: see text]). In the reflection spectrum, the two reflection peaks are all redshifted relative to that of the BN-doped system (the torsion angle is 0[Formula: see text]) and when the torsion angle exceeds 12[Formula: see text], the size relationship between the two peaks is interchanged. The results of this paper are of guiding significance for the study of graphene-based nanotube devices in terms of deformation.

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