Electronic Structure of Ta2O5 Polymorphs: Variation Trend of Band Gap and the Role of Oxygen Vacancies

作     者：Tang, Hui-Min Yang, Yong 

作者机构：School of Physical Science and Technology Guangxi Normal University Guilin541001 China Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid State Physics HFIPS Chinese Academy of Sciences Hefei230031 China Science Island Branch of Graduate School University of Science and Technology of China Hefei230026 China 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2023年

核心收录：

主　　题：Energy gap 

摘      要：We provide a systematic study on the electronic structure of a series of Ta2O5 polymorphs using standard density functional theory (DFT) calculations as well as the more accurate many-body perturbation theory within the GW approximation. For the defect-free polymorphs, the variation trend of band gap can be microscopically related to the strength of orbital hybridization, and to the macroscopic bulk formation energy. The presence of oxygen vacancies is found to have profound effects on the electronic properties near the Fermi level, notably the reduction of band gap and gap closure (insulator-to-metal transition). Furthermore, depending on the vacancy sites, the band gap of some defective system may be enlarged with comparison to its defect-free counterpart. Such an anomalous behavior originates from the unexpected formation of Ta-Ta bonds. © 2023, CC BY.