Instituto de Física, Facultad de Ingeniería , Universidad de la República , Herrera y Reissig 565, C.C. 30 , 11000 Montevideo , Uruguay.
Swiss Federal Laboratories for Materials Science and Technology (Empa) , Überlandstrasse 129 , 8600 Dübendorf , Switzerland.
ACS Appl Mater Interfaces. 2018 Jun 20;10(24):20938-20949. doi: 10.1021/acsami.8b02653. Epub 2018 Jun 7.
Multilayered structures are a promising route to tailor electronic, magnetic, optical, and/or mechanical properties and durability of functional materials. Sputter deposition at room temperature, being an out-of-equilibrium process, introduces structural defects and confers to these nanosystems an intrinsic thermodynamical instability. As-deposited materials exhibit a large amount of internal atomic displacements within each constituent block as well as severe interface roughness between different layers. To access and characterize the internal multilayer disorder and its thermal evolution, X-ray diffraction investigation and analysis are performed systematically at differently grown Ag-Ge/aluminum nitride (AlN) multilayers (co-deposited, sequentially deposited with and without radio frequency (RF) bias) samples and after high-temperature annealing treatment. We report here on model calculations based on a kinematic formalism describing the displacement disorder both within the multilayer blocks and at the interfaces to reproduce the experimental X-ray diffraction intensities. Mixing and displacements at the interface are found to be considerably reduced after thermal treatment for co- and sequentially deposited Ag-Ge/AlN samples. The application of a RF bias during the deposition causes the highest interface mixing and introduces random intercalates in the AlN layers. X-ray analysis is contrasted to transmission electron microscopy pictures to validate the approach.
多层结构是一种很有前途的方法，可以调整功能材料的电子、磁、光和/或机械性能和耐久性。在室温下进行的溅射沉积是一种非平衡过程，会引入结构缺陷，并使这些纳米系统具有内在的热力学不稳定性。沉积后的材料在每个组成块内表现出大量的原子内位移，以及不同层之间严重的界面粗糙度。为了获取和表征内部多层无序及其热演化，我们系统地对不同生长的 Ag-Ge/氮化铝（AlN）多层（共沉积、有/无射频（RF）偏压顺序沉积）样品以及高温退火处理后的样品进行了 X 射线衍射研究和分析。我们在这里报告了基于运动学形式主义的模型计算，该形式主义描述了多层块内和界面处的位移无序，以再现实验 X 射线衍射强度。结果表明，共沉积和顺序沉积的 Ag-Ge/AlN 样品经过热处理后，界面混合和位移显著减少。在沉积过程中施加 RF 偏压会导致最高的界面混合，并在 AlN 层中引入随机夹层。X 射线分析与透射电子显微镜图片进行了对比，以验证该方法。
