Structural Transitions in Ge2Sb2Te5 Phase Change Memory Thin Films Induced by Nanosecond UV Optical Pulses
Structural Transitions in Ge2Sb2Te5 Phase Change Memory Thin Films Induced by Nanosecond UV Optical Pulses
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DOI：
10.3390/ma13092082
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发表时间：
2020-05
期刊：
影响因子：
3.4
通讯作者：
Mario Behrens;A. Lotnyk;Hagen Bryja;J. Gerlach;B. Rauschenbach
中科院分区：
文献类型：
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作者：
Mario Behrens;A. Lotnyk;Hagen Bryja;J. Gerlach;B. Rauschenbach
Ge-Sb-Te基相变记忆合金在光子学、非易失性数据存储和神经形态计算等领域具有广阔的应用前景，近年来引起了人们的广泛关注。特别感兴趣的是理解短光脉冲引起的结构变化和潜在机制。本工作报告的结构变化引起的单纳秒紫外激光脉冲在非晶和外延Ge 2Sb 2 Te 5（GST）薄膜。利用X射线衍射和透射电子显微镜相结合的方法研究了薄膜内的相变。结果表明，不同的相变，如晶体到非晶相变，界面辅助结晶的立方GST相和晶相内的结构转变。特别是，它被发现，结晶界面作为结晶模板外延形成的亚稳立方GST相相变时。通过改变激光能量密度，GST薄膜组成的多个阶段和不同的非晶结晶的体积比，可以在这种方法中实现，提供了一种可能性的多级数据存储和实现的存储设备具有非常低的电阻漂移。此外，本工作演示了非晶化和结晶的GST薄膜，只用一个紫外激光与一个单一的脉冲宽度和一个波长。总体而言，所呈现的结果提供了新的视角，在Ge-Sb-Te基材料的开关路径，并显示了潜在的外延Ge-Sb-Te薄膜的应用在先进的相变存储器的概念。
Ge-Sb-Te-based phase change memory alloys have recently attracted a lot of attention due to their promising applications in the fields of photonics, non-volatile data storage, and neuromorphic computing. Of particular interest is the understanding of the structural changes and underlying mechanisms induced by short optical pulses. This work reports on structural changes induced by single nanosecond UV laser pulses in amorphous and epitaxial Ge2Sb2Te5 (GST) thin films. The phase changes within the thin films are studied by a combined approach using X-ray diffraction and transmission electron microscopy. The results reveal different phase transitions such as crystalline-to-amorphous phase changes, interface assisted crystallization of the cubic GST phase and structural transformations within crystalline phases. In particular, it is found that crystalline interfaces serve as crystallization templates for epitaxial formation of metastable cubic GST phase upon phase transitions. By varying the laser fluence, GST thin films consisting of multiple phases and different amorphous to crystalline volume ratios can be achieved in this approach, offering a possibility of multilevel data storage and realization of memory devices with very low resistance drift. In addition, this work demonstrates amorphization and crystallization of GST thin films by using only one UV laser with one single pulse duration and one wavelength. Overall, the presented results offer new perspectives on switching pathways in Ge-Sb-Te-based materials and show the potential of epitaxial Ge-Sb-Te thin films for applications in advanced phase change memory concepts.