Band Structure Engineering: Insights from Defects, Band Gap, and Electron Mobility, from Study of Magnesium Tantalate

Taifeng Liu, Michel Dupuis, Can Li

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Anion doping of semiconductors with nitrogen is a strategy often adopted to narrow the band gap of semiconductors and increase the range of light absorption. However, the influence of nitrogen doping on the electron mobility in the semiconductor is not fully understood and characterized. In this work, we used magnesium tantalate MgTa2O6 as a model system and hybrid density-functional theory calculations to characterize the mobility of electrons using the small polaron model in the presence of nitrogen-doping defects as well as oxygen-vacancy defects. We found that electron mobility is not significantly affected when MgTa2O6 is doped with a molar ratio N/O of ∼2%. However, in the presence of oxygen vacancies combined with nitrogen doping with the same molar ratio N/O of ∼2%, the barrier to electron hopping in the vicinity of the defects is much lower than that in pristine MgTa2O6 and in MgTa2O6 with oxygen-vacancy defects only. These results suggest that nitrogen doping combined with anion vacancy not only narrows band gap but also enhances electron mobility, a finding that may lead to new strategies toward synthesizing more efficient photocatalysts. (Figure Presented).

Original languageEnglish
Pages (from-to)6930-6937
Number of pages8
JournalJournal of Physical Chemistry C
Volume120
Issue number13
DOIs
Publication statusPublished - Apr 7 2016

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Electron mobility
electron mobility
Band structure
Magnesium
magnesium
Energy gap
Nitrogen
Doping (additives)
engineering
nitrogen
Oxygen vacancies
Defects
defects
Semiconductor materials
Anions
oxygen
Negative ions
anions
Gene Conversion
Electrons

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Band Structure Engineering : Insights from Defects, Band Gap, and Electron Mobility, from Study of Magnesium Tantalate. / Liu, Taifeng; Dupuis, Michel; Li, Can.

In: Journal of Physical Chemistry C, Vol. 120, No. 13, 07.04.2016, p. 6930-6937.

Research output: Contribution to journalArticle

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abstract = "Anion doping of semiconductors with nitrogen is a strategy often adopted to narrow the band gap of semiconductors and increase the range of light absorption. However, the influence of nitrogen doping on the electron mobility in the semiconductor is not fully understood and characterized. In this work, we used magnesium tantalate MgTa2O6 as a model system and hybrid density-functional theory calculations to characterize the mobility of electrons using the small polaron model in the presence of nitrogen-doping defects as well as oxygen-vacancy defects. We found that electron mobility is not significantly affected when MgTa2O6 is doped with a molar ratio N/O of ∼2{\%}. However, in the presence of oxygen vacancies combined with nitrogen doping with the same molar ratio N/O of ∼2{\%}, the barrier to electron hopping in the vicinity of the defects is much lower than that in pristine MgTa2O6 and in MgTa2O6 with oxygen-vacancy defects only. These results suggest that nitrogen doping combined with anion vacancy not only narrows band gap but also enhances electron mobility, a finding that may lead to new strategies toward synthesizing more efficient photocatalysts. (Figure Presented).",
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