State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
Nanoscale. 2019 Jan 23;11(4):1595-1603. doi: 10.1039/c8nr07832g.
Germanium chalcogenides, especially GeSe and GeTe alloys, have recently gained popularity because of their Ovonic threshold (volatile) and memory (non-volatile) switching properties, with great potential for electric storage applications. Materials designed in a pseudo-binary way may possess superior properties in their phase transition, e.g. GeTe-Sb2Te3 materials, and bring about revolutionary advances in optical storage. However, to date, the electrical switching behaviors of films of pseudo-binary GeSe-GeTe have not yet been studied, and neither have the structural characteristics. Herein, we present both the thermally and electrically induced switching behaviors of GeSe-GeTe film, as well as the structural evolution due to composition tuning. The crystallization temperature of GeSe-GeTe films increases with GeSe content quite sensitively. An atom-resolved picture of the GeSe-GeTe alloy with a state-of-the-art atomic mapping technology has been presented, where a randomly mixed arrangement of Se and Te atoms is determined unambiguously in Ge50Se13Te34 with a GeTe-like rhombohedral structure. The local structural motifs in GeSe-GeTe, more specifically, sixfold coordinated octahedra with a distinguished degree of Peierls distortion and geometric variety, are essential to understand its electric properties. GeSe-GeTe alloy, Ge50Se13Te34, based memory cells have been fabricated, showing a fast memory switching behavior and excellent retention of 10 years at 208 °C.
锗硫属化物，特别是 GeSe 和 GeTe 合金，由于其具有类 OVONIC （易失性）和记忆（非易失性）开关特性，在储能应用方面具有巨大的潜力，因此最近受到了广泛关注。采用准二元设计的材料在相变方面可能具有更优越的性能，例如 GeTe-Sb2Te3 材料，并且可能会在光存储方面带来革命性的进步。然而，迄今为止，对于准二元 GeSe-GeTe 薄膜的电开关行为尚未进行研究，其结构特性也尚未研究。在此，我们研究了 GeSe-GeTe 薄膜的热诱导和电诱导开关行为，以及由于组成调谐引起的结构演变。GeSe-GeTe 薄膜的结晶温度随 GeSe 含量的增加而非常敏感地增加。利用原子分辨技术，我们提出了 GeSe-GeTe 合金的原子分辨图像，其中明确确定了 Ge50Se13Te34 中具有 GeTe 型三角结构的 Se 和 Te 原子的随机混合排列。GeSe-GeTe 中的局部结构基元，特别是具有明显程度的 Peierls 畸变和几何多样性的六配位八面体，对于理解其电性质至关重要。已经制备了基于 GeSe-GeTe 合金的记忆单元，该单元显示出快速的记忆开关行为和在 208°C 下 10 年的优异保持性。
