Barium disilicide (BaSi) is a semiconductor with promising photovoltaic properties. To build efficient devices, a good understanding of its defects is required. In this article, we present the first systematic study of such defects in a series of BaSi samples synthetized in Barium-rich and Silicon-rich conditions. We combined electron paramagnetic resonance (EPR), Photoluminescence (PL) and density functional theory (DFT) to complete our analysis. With these techniques, we spectroscopically characterized five paramagnetic defect centers (defect 1 to defect 5) and four PL centers (P0 to P3). We identified several of them: in Ba-rich conditions, defect 5 corresponds to the negatively charged silicon vacancy V. In Si-rich conditions, defect 1 and defect 2 correspond to a negatively charged complex defect O, consisting of a pseudotetrahedron of 3 silicon and 1 oxygen in two slightly different environments. For PL, we attributed two bands (P0 and P1) to transitions involving O once again; P2 and P3 were attributed to transitions involving another complex defect [OS], an interstitial silicon in close proximity to an interstitial oxygen. The existence of these defects rationalizes previous reports in the literature, in particular the increased photoresponse upon hydrogen passivation.

中文翻译：

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通过电子顺磁共振、光致发光和密度泛函理论识别和分析BaSi2中的点缺陷


二硅化钡（BaSi）是一种具有前景的光伏特性的半导体。为了构建高效的设备，需要充分了解其缺陷。在本文中，我们首次系统地研究了在富钡和富硅条件下合成的一系列 BaSi 样品中的此类缺陷。我们结合电子顺磁共振（EPR）、光致发光（PL）和密度泛函理论（DFT）来完成我们的分析。利用这些技术，我们对五个顺磁缺陷中心（缺陷 1 至缺陷 5）和四个 PL 中心（P0 至 P3）进行了光谱表征。我们确定了其中的几个：在富 Ba 条件下，缺陷 5 对应于带负电的硅空位 V。在富 Si 条件下，缺陷 1 和缺陷 2 对应于带负电的复合缺陷 O，由 3 个硅组成的伪四面体组成。和 1 个氧气在两个略有不同的环境中。对于 PL，我们再次将两个带（P0 和 P1）归因于涉及 O 的跃迁； P2 和 P3 归因于涉及另一种复杂缺陷 [OS] 的转变，即与间隙氧非常接近的间隙硅。这些缺陷的存在合理化了文献中先前的报道，特别是氢钝化后光响应的增加。