The state-of-the-art phase-change memory is usually composed of ovonic threshold switching (OTS) material and ovonic memory switching (OMS) material for selective and data storage, respectively. OMS materials have been intensely studied, while the knowledge of the OTS mechanism is still inadequate. In this article, we have explored the local structure and electronic property of a simple OTS material, the amorphous (a-) SiTe, by first-principles calculations. The results reveal that most of the atoms in a-SiTe obey the “8-N” rule in contrast to a-GeTe, a well-studied OMS material. 76.5% of Si-centered configurations are in the form of randomly distributed tetrahedral clusters, while Te-centered configurations are relatively disordered without notable conformation. Furthermore, a large number of fivefold rings are found in a-SiTe. All of these structural characteristics lead to the high stability of a-SiTe, prohibiting its crystallization. In addition, the p state of Te also contributes much to the mid-gap states, which may be relevant for OTS behavior. Our findings provide an in-depth understanding of the structural signature and electronic properties of a-SiTe, having important implications for the design and applications of OTS materials.

中文翻译：

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硫属化物玻璃 SiTe 的结构特征：一种 ovonic 阈值切换材料

最先进的相变存储器通常由 ovonic 阈值切换 (OTS) 材料和 ovonic 存储器切换 (OMS) 材料组成，分别用于选择性和数据存储。OMS 材料已被深入研究，而 OTS 机制的知识仍然不足。在本文中，我们通过第一性原理计算探索了一种简单的 OTS 材料非晶 (a-) SiTe 的局部结构和电子特性。结果表明，与经过充分研究的 OMS 材料 a-GeTe 相比，a-SiTe 中的大多数原子遵循“8-N”规则。76.5% 的以 Si 为中心的构型是随机分布的四面体簇的形式，而以 Te 为中心的构型相对无序，没有明显的构象。此外，在 a-SiTe 中发现了大量的五重环。所有这些结构特征导致 a-SiTe 的高稳定性，阻止其结晶。此外，Te 的 p 状态也对中间间隙状态有很大贡献，这可能与 OTS 行为有关。我们的发现深入了解了 a-SiTe 的结构特征和电子特性，对 OTS 材料的设计和应用具有重要意义。