Switching mechanisms in metastable multilayer systems

用于非易失性数据存储的碲基相变材料（PCM）形成了一个密集的跨学科研究领域。在过去，Ge-Sb-Te系统的均匀薄膜是研究的焦点，其可以通过加热、施加电压脉冲或通过用激光脉冲照射而在非晶相和晶相之间可逆地切换。这种相变伴随着光学和电学性质的强烈变化，可以很容易地读出。在本申请中，我们将专注于两种新型相变系统，即非晶和结晶多层复合材料，与现有材料相比，它们仍然为最高水平的基础研究提供了许多起点。在结晶多层系统（所谓的iPCM）的情况下，一个特别节能的开关机制进行了讨论，这是有关的结晶组件的界面处的结构变化。然而，它还没有能够实验验证现有的理论有关的开关机制。在该项目中，Sb 2 Te 3和GeTe或新的Ge 4Se 3 Te将通过脉冲激光烧蚀（PLD）沉积作为用于两种相变系统的多层膜的组分。这些材料应该通过光学、电学和加热进行转换，并在结构和功能上进行表征。这里的目标是，例如，以确定在不同的转换时间的结构变化，并从这些数据中得出可能的转换机制。为了实现这些目标，必须构建用于电气开关和用于确定电气特性的测量设置，以及必须设计用于结构化样品的光刻方法。一个协同组合的非原位和原位的方法，重点是透射电子显微镜和X射线衍射应涵盖不同的长度尺度上可能的开关机制，使结构-性能关系可以推断。

Telluride-based phase change materials (PCM) for non-volatile data storage form an intensive and interdisciplinary research field. In the past, homogeneous thin films of the Ge-Sb-Te system were the focus of research, which can be reversibly switched between an amorphous and a crystalline phase by heat, application of a voltage pulse or by irradiation with laser pulses. This phase change is accompanied by strong changes in the optical and electrical properties that can be easily read out. In the present application, we will focus on two novel phase change systems, namely amorphous and crystalline multilayer composites, which, in contrast to the established materials, still offer numerous starting points for basic research at the highest level. In the case of crystalline multilayer systems (so-called iPCM), a particularly energy-efficient switching mechanism is discussed, which is related to structural changes at the interfaces of the crystalline components. However, it has not yet been possible to experimentally verify existing theories regarding the switching mechanism. In this project, Sb2Te3 and GeTe or the new Ge4Se3Te are to be deposited as components of the multilayers for both phase change systems by pulsed laser ablation (PLD). The materials should be switched optically, electrically and by heating and characterized both structurally and functionally. The goal is here e.g. to identify structural changes at different switching times and to derive possible switching mechanisms from these data. In order to achieve these goals, measurement setups for electrical switching and for determining the electrical properties have to be constructed, as well as lithographic methods for structuring the samples have to be designed. A synergistic combination of ex situ and in situ methods with a focus on transmission electron microscopy and X-ray diffraction should cover possible switching mechanisms on different length scales so that structure-property relationships can be deduced.