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Multistability of isolated and hydrogenated Ga–O divacancies inβ−Ga2O3
Physical Review Materials ( IF 3.4 ) Pub Date : 2021-02-03 , DOI: 10.1103/physrevmaterials.5.025402
Y. K. Frodason , C. Zimmermann , E. F. Verhoeven , P. M. Weiser , L. Vines , J. B. Varley

This work systematically explores 19 unique configurations of the close-associate Ga–O divacancies (VGaVO) in βGa2O3, including their complexes with H impurities, using hybrid functional calculations. Interestingly, most configurations are found to retain the negative-U behavior of VO, as they exhibit a thermodynamic (/3) charge-state transition level energetically located in the upper part of the band gap, where the 3 charge state is associated with the formation of a Ga–Ga dimer. The energy positions of the thermodynamic (/3) charge-state transition levels divide the divacancy configurations into three different groups, which can be understood from the three possible Ga–Ga dimerizations resulting from the tetrahedral and octahedral Ga sites. The relative formation energies of the different divacancy configurations, and hence the electrical activity of the divacancies, is found to depend on the Fermi-level position, and the energy barriers for transformation between different divacancy configurations are explored from nudged elastic band calculations. Hydrogenation of the divacancies is found to either passivate their negative-U charge-state transition levels or shift them down in Fermi level position, depending on whether the H resides at VO or forms an O–H bond at VGa, respectively. Finally, the divacancy is discussed as a potential origin of the so-called E2* center previously observed by deep-level transient spectroscopy.

中文翻译:

β-Ga2O3中孤立和氢化的Ga–O双空位的多重稳定性

这项工作系统地探索了紧密关联的Ga–O空位的19个独特配置 VVØβ-2Ø3,包括它们与H杂质的配合物,使用混合泛函计算。有趣的是,发现大多数配置都保留了ü 的行为 VØ,因为它们具有热力学特性(-/3-)电荷态跃迁能级大体位于带隙的上部 3-电荷状态与Ga-Ga二聚体的形成有关。热力学的能量位置(-/3-)电荷态跃迁能级将空位构型分为三个不同的组,这可以从四面体和八面体Ga位点产生的三种可能的Ga-Ga二聚化中理解。发现不同空位构型的相对形成能以及因此的空位电活性取决于费米能级位置,并且从微动的弹性带计算中探索了用于不同空位构型之间转换的能垒。发现空位氢化可以钝化它们的负-ü 电荷状态转换能级或将它们向下移到费米能级位置,具体取决于H是否位于 VØ 或在 V, 分别。最后,空缺被讨论为所谓的潜在来源Ë2* 中心以前通过深层瞬态光谱观察到。
更新日期:2021-02-03
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