Realization of Electron Antidoping by Modulating the Breathing Distortion in BaBiO<sub>3</sub>.

Cao, Hui; Guo, Hongli; Shao, Yu-Cheng; Liu, Qixin; Feng, Xuefei; Lu, Qinwen; Wang, Zhongping; Zhao, Aidi et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

The recent proposal of antidoping scheme breaks new ground in conceiving conversely functional materials and devices; yet, the few available examples belong to the correlated electron systems. Here, we demonstrate both theoretically and experimentally that the main group oxide BaBiO<sub>3</sub> is a model system for antidoping using oxygen vacancies. The first-principles calculations show that the band gap systematically increases due to the strongly enhanced Bi-O breathing distortions away from the vacancies and the annihilation of Bi 6<i>s</i>/O 2<i>p</i> hybridized conduction bands near the vacancies. Our further spectroscopic experiments confirm that the band gap increases systematically with electron doping, with a maximal gap enhancement of ∼75% when the film's stoichiometry is reduced to BaBiO<sub>2.75</sub>. These results unambiguously demonstrate the remarkable antidoping effect in a material without strong electron correlations and underscores the importance of bond disproportionation in realizing such an effect.