Understanding the nature of the mid-gap defects in amorphous chalcogenide alloy-based phase change materials is crucial to guide the development of multi-level memories, selectors, and neuromorphic devices. Currently, however, the knowledge of the mid-gap defects is fragmented and the known structural and electrical characteristics of the defects cannot be unified in a single atomic model. In this work, a Ge–Ge chain defect model is built by artificial bond rearrangement in an amorphous GeTe network generated by atomic distortion, revealing a possible valence alternation mechanism in its formation. Atoms in the Ge–Ge chain are found to have a crystalline-like environment. The chain is found to have a negative-U property and to introduce mid-gap states. This model unifies the main known properties of the mid-gap defects in amorphous chalcogenide alloy-based phase change materials.

中文翻译：

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非晶GeTe相变材料的统一中带隙缺陷模型

了解基于非晶硫属化物合金的相变材料中间隙缺陷的性质对于指导多级存储器、选择器和神经形态器件的开发至关重要。然而，目前，中带缺陷的知识是零散的，缺陷的已知结构和电气特性无法统一在单个原子模型中。在这项工作中，通过在由原子畸变产生的非晶 GeTe 网络中人工键重排建立 Ge-Ge 链缺陷模型，揭示了其形成过程中可能的价态交替机制。发现 Ge-Ge 链中的原子具有类似晶体的环境。发现该链具有负 U 特性并引入中间间隙状态。