scholarly journals Ab-Initio Calculations of Oxygen Vacancy in Ga2O3 Crystals

2021 ◽  
Vol 58 (2) ◽  
pp. 3-10
Author(s):  
A. Usseinov ◽  
Zh. Koishybayeva ◽  
A. Platonenko ◽  
A. Akilbekov ◽  
J. Purans ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Gallium Oxide ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Wide Band ◽  
Electronic Charge ◽  
Charge Redistribution ◽  
Wide Band Gap ◽  
Exchange Correlation ◽  
Deep Donor

Abstract Gallium oxide β-Ga2O3 is an important wide-band gap semiconductor. In this study, we have calculated the formation energy and transition levels of oxygen vacancies in β-Ga2O3 crystal using the B3LYP hybrid exchange-correlation functional within the LCAO-DFT approach. The obtained electronic charge redistribution in perfect Ga2O3 shows notable covalency of the Ga-O bonds. The formation of the neutral oxygen vacancy in β-Ga2O3 leads to the presence of deep donor defects with quite low concentration. This is a clear reason why oxygen vacancies can be hardly responsible for n-type conductivity in β-Ga2O3.

scholarly journals Influence of Mixed Valence on the Formation of Oxygen Vacancy in Cerium Oxides

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4041 ◽  
Author(s):  
Gege Zhou ◽  
Wentong Geng ◽  
Lu Sun ◽  
Xue Wang ◽  
Wei Xiao ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Valence State ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Mixed Valence ◽  
Oxygen Storage ◽  
Electronic Charge ◽  
Covalent Bonds ◽  
Cerium Oxides

Ceria is one of the most important functional rare-earth oxides with wide industrial applications. Its amazing oxygen storage/release capacity is attributed to cerium’s flexible valence conversion between 4+ and 3+. However, there still exists some debate on whether the valence conversion is due to the Ce-4f electron localization-delocalization transition or the character of Ce–O covalent bonds. In this work, a mixed valence model was established and the formation energies of oxygen vacancies and electronic charges were obtained by density functional theory calculations. Our results show that the formation energy of oxygen vacancy is affected by the valence state of its neighboring Ce atom and two oxygen vacancies around a Ce4+ in CeO2 have a similar effect to a Ce3+. The electronic charge difference between Ce3+ and Ce4+ is only about 0.4e. Therefore, we argue that the valence conversion should be understood according to the adjustment of the ratio of covalent bond to ionic bond. We propose that the formation energy of oxygen vacancy be used as a descriptor to determine the valence state of Ce in cerium oxides.

scholarly journals Charge-Transfer Induced by the Oxygen Vacancy Defects in the Ag/MoO3 Composite System

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1292
Author(s):  
Qi Chu ◽  
Jingmeng Li ◽  
Sila Jin ◽  
Shuang Guo ◽  
Eungyeong Park ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Oxygen Vacancy ◽  
Composite System ◽  
Wide Band ◽  
Utilization Rate ◽  
Wide Band Gap ◽  
Interesting Phenomenon ◽  
Vacancy Defects ◽  
Characterization Methods ◽  
Surface Enhanced Raman

In this paper, an Ag/MoO3 composite system was cosputtered by Ar plasma bombardment on a polystyrene (PS) colloidal microsphere array. The MoO3 formed by this method contained abundant oxygen vacancy defects, which provided a channel for charge transfer in the system and compensated for the wide band gap of MoO3. Various characterization methods strongly demonstrated the existence of oxygen vacancy defects and detected the properties of oxygen vacancies. 4-Aminothiophenol (p-aminothiophenol, PATP) was used as a candidate surface-enhanced Raman scattering (SERS) probe molecule to evaluate the contribution of the oxygen vacancy defects in the Ag/MoO3 composite system. Interestingly, oxygen vacancy defects are a kind of charge channel, and their powerful effect is fully reflected in their SERS spectra. Increasing the number of charge channels and increasing the utilization rate of the channels caused the frequency of SERS characteristic peaks to shift. This interesting phenomenon opens up a new horizon for the study of SERS in oxygen-containing semiconductors and provides a powerful reference for the study of PATP.

Formation of oxygen vacancies in Li2FeSiO4: first-principles calculations

2021 ◽  
Vol 23 (36) ◽  
pp. 20444-20452
Author(s):  
Lihong Zhang ◽  
Shunqing Wu ◽  
Jianwei Shuai ◽  
Zhufeng Hou ◽  
Zizhong Zhu
Keyword(s):  
Oxygen Vacancy ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Vacancy Formation Energy ◽  
Vacancy Formation ◽  
First Principles Calculations ◽  
Temperature And Pressure

The oxygen vacancy (left panel) and the vacancy formation energy as a function of temperature and pressure (right panel).

scholarly journals Nucleation-controlled vacancy formation in light-emitting wide-band-gap oxide nanocrystals in glass

2015 ◽  
Vol 3 (17) ◽  
pp. 4380-4387 ◽  
Author(s):  
N. V. Golubev ◽  
E. S. Ignat'eva ◽  
V. N. Sigaev ◽  
L. De Trizio ◽  
A. Azarbod ◽  
...  
Keyword(s):  
Band Gap ◽  
Gallium Oxide ◽  
Wide Band ◽  
Nanocrystal Size ◽  
Vacancy Formation ◽  
Wide Band Gap ◽  
Light Emitting ◽  
Donor Acceptor

Controlling nanocrystal nucleation in a solid host, as in the gallium-oxide nanophase grown in glass, provides a strategy for tailoring not only nanocrystal size but also light-emitting donor–acceptor population.

Novel N-Black In2O3-x/InVO4 heterojunction for efficient photocatalytic fixation: Synergistic effect of exposed (321) facet and oxygen vacancy

2021 ◽  
Author(s):  
Jin Ye ◽  
Jiating Xu ◽  
Chunsheng Li ◽  
Di Tian ◽  
Xiaohan Zhao ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Synergistic Effect ◽  
Band Gap ◽  
Recombination Rate ◽  
Wide Band ◽  
Great Promise ◽  
Wide Band Gap ◽  
High Recombination Rate ◽  
Energy Shortage

Utilizing semiconductors to catalyze N2 into NH3 has brought great promise in alleviating the issue of energy shortage. However, the wide band gap and high recombination rate of photogenerated (e-/h+)...

A Unifying Perspective on Oxygen Vacancies in Wide Band Gap Oxides

2017 ◽  
Vol 9 (1) ◽  
pp. 222-228 ◽  
Author(s):  
Christopher Linderälv ◽  
Anders Lindman ◽  
Paul Erhart
Keyword(s):  
Band Gap ◽  
Oxygen Vacancies ◽  
Wide Band ◽  
Wide Band Gap

First principles study of oxygen vacancies in (Mo + C)-doped anatase TiO2

2015 ◽  
Vol 29 (14) ◽  
pp. 1550072 ◽  
Author(s):  
Jie Cui ◽  
Shuhua Liang ◽  
Xianhui Wang ◽  
Jianmin Zhang
Keyword(s):  
Oxygen Vacancy ◽  
Fermi Level ◽  
Conduction Band ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Anatase Tio2 ◽  
Metallic Behavior ◽  
Structural And Electronic Properties ◽  
Projector Augmented Wave

The structural and electronic properties of neutral oxygen vacancies in ( Mo + C )-doped anatase TiO 2 were investigated using frozen-core projector-augmented wave (PAW) method within GGA +U approximation. Six possible oxygen vacancy sites were considered in the present work. The results show that the octahedral vertex adjacent to Mo and opposite from C is the most stable position for oxygen vacancy based on the results of the formation energy. The Fermi level is located at above the bottom of the conduction band and a typical n-type metallic behavior occurs as a result of the oxygen vacancy appeared in ( Mo + C ) doped TiO 2.

Local-Field and Exchange-Correlation Effects in Optical Spectra of Wide-Band–Gap Semiconductors

1996 ◽  
Vol 423 ◽  
Author(s):  
V. I. Gavrilenko ◽  
F. Bechstedt
Keyword(s):  
Local Field ◽  
Density Functional ◽  
Random Phase ◽  
Wide Band ◽  
Optical Spectra ◽  
Wide Band Gap ◽  
Functional Theory ◽  
Exchange Correlation ◽  
The Density Functional Theory ◽  
Wide Band Gap Semiconductors

AbstractThe density-functional theory with ab initio pseudopotentials has been used to study the linear optical response of semiconductors. We present results for optical spectra where the effects of the macroscopic local-field and microscopic exchange-correlation interaction are included beyond diagonal and random-phase approximation. Quasiparticle corrections to the single-particle energies have been added in the polarization function. Numerical calculations are performed for the column-IV materials Si, SiC, and diamond as model substances.

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