Van der Waals interfacial bonding and intermixing in GeTe-Sb2Te3-based superlattices  

作　　者：Andriy Lotnyk Isom Hilmi Ulrich Ross Bernd Rauschenbach 

机构地区：[1]Leibniz Institute of Surface Modification (IOM), Permoserstr. 15, Leipzig D-04318, Germany

出　　处：《Nano Research》2018年第3期1676-1686,共11页纳米研究（英文版）

摘　　要：Interfacial phase change memory （iPCM） based on GeTe and Sb2Te3 superlattices （SLs） is an emerging contender for non-volatile data storage applications. A detailed knowledge of the atomic structure of these materials is crucial for further development of SLs and for a better understanding of the resistivity switching characteristics of iPCM devices. In this work, crystalline GeTe-Sb2TeB- based SLs, produced by pulsed laser deposition onto a Si（111） substrate at temperatures lower than in previous studies, are analyzed by advanced scanning transmission electron microscopy. The results reveal the formation of Ge-rich Ge（x＋y）Sb（2-y）Tez building blocks with specific numbers of ordered Ge cation layers （between I and 5） and disordered cation layers （4） for z = 6-10, as well as intermixed cation layers for z = 5, within the SLs. The G Ge（x＋y）Sb（2-y）Tez units are separated from the Sb2Te3 building blocks by van der Waals gaps. In particular, the interlayer bonding is promoted by the formation of outermost cation layers consisting of intermixed GeSb within the building blocks adjacent to the van der Waals gaps. The Ge（x＋y）Sb（2-y）Tez units with z 〉 5 retain metastable crystal structures with two-dimensional bonding within the SLs. The present study shed new light on the possible configurations of the building units that can be formed during the synthesis of GeTe-Sb2Te3-based iPCM materials. In addition, a possible switching mechanism active in iPCM materials is discussed.Interfacial phase change memory （iPCM） based on GeTe and Sb2Te3 superlattices （SLs） is an emerging contender for non-volatile data storage applications. A detailed knowledge of the atomic structure of these materials is crucial for further development of SLs and for a better understanding of the resistivity switching characteristics of iPCM devices. In this work, crystalline GeTe-Sb2TeB- based SLs, produced by pulsed laser deposition onto a Si（111） substrate at temperatures lower than in previous studies, are analyzed by advanced scanning transmission electron microscopy. The results reveal the formation of Ge-rich Ge（x＋y）Sb（2-y）Tez building blocks with specific numbers of ordered Ge cation layers （between I and 5） and disordered cation layers （4） for z = 6-10, as well as intermixed cation layers for z = 5, within the SLs. The G Ge（x＋y）Sb（2-y）Tez units are separated from the Sb2Te3 building blocks by van der Waals gaps. In particular, the interlayer bonding is promoted by the formation of outermost cation layers consisting of intermixed GeSb within the building blocks adjacent to the van der Waals gaps. The Ge（x＋y）Sb（2-y）Tez units with z 〉 5 retain metastable crystal structures with two-dimensional bonding within the SLs. The present study shed new light on the possible configurations of the building units that can be formed during the synthesis of GeTe-Sb2Te3-based iPCM materials. In addition, a possible switching mechanism active in iPCM materials is discussed.

关 键 词：interfacial phase change memory （iPCM） thin films INTERMIXING Cs-corrected scanningtransmission electron microscopy 

分 类 号：TP317[自动化与计算机技术—计算机软件与理论] TG13[自动化与计算机技术—计算机科学与技术]