Solid-state dewetting of single- and bilayer Au-W thin films: Unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution
Solid-state dewetting of single- and bilayer Au-W thin films: Unraveling the role of individual layer thickness, stacking sequence and oxidation on morphology evolution
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DOI：
10.1063/1.4944348
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发表时间：
2016-03-01
期刊：
影响因子：
1.6
通讯作者：
Schaaf, P.
中科院分区：
文献类型：
--
作者：
Herz, A.;Franz, A.;Schaaf, P.
采用快速热退火技术在惰性气氛中研究了Au、W和Au-W双层薄膜的自组装。固态去湿的Au膜的简要回顾，以强调初始膜厚度的作用。沉积在SiO2上的W膜在高温下退火时演变成针状纳米晶体，而不是形成颗粒状团聚体。透射电子显微镜显示，这种纳米晶体实际上由钨（VI）氧化物（WO 3），这是有关的各向异性的氧化物晶体生长出的薄膜。W膜的演化对任何残余氧的存在高度敏感。通过使用不互溶的Au和W的各种双层膜结构，实现了Au的去润湿和WO 3的氧化物晶体生长的组合。在低温下，Au去湿开始，而氧化物晶体生长仍然受到抑制。取决于Au-W双层薄膜的堆叠顺序，W充当基底或钝化层以用于Au的去润湿。作为基底层，W改变了Au的润湿性，这明显地改变了其去润湿的初始状态。作为顶层，W防止Au去湿，而与Au膜厚度无关。此外，在高温下观察到Au-WO 3纳米颗粒的规则图案形成，表明双层薄膜去湿可以产生独特的纳米结构排列。(C)2016年作者。
Self-assembly of ultrathin Au, W, and Au-W bilayer thin films is investigated using a rapid thermal annealing technique in an inert ambient. The solid-state dewetting of Au films is briefly revisited in order to emphasize the role of initial film thickness. W films deposited onto SiO2 evolve into needle-like nanocrystals rather than forming particle-like agglomerates upon annealing at elevated temperatures. Transmission electron microscopy reveals that such nanocrystals actually consist of tungsten (VI) oxide (WO3) which is related to an anisotropic oxide crystal growth out of the thin film. The evolution of W films is highly sensitive to the presence of any residual oxygen. Combination of both the dewetting of Au and the oxide crystal growth of WO3 is realized by using various bilayer film configurations of the immiscible Au and W. At low temperature, Au dewetting is initiated while oxide crystal growth is still suppressed. Depending on the stacking sequence of the Au-W bilayer thin film, W acts either as a substrate or as a passivation layer for the dewetting of Au. Being the ground layer, W changes the wettability of Au which clearly modifies its initial state for the dewetting. Being the top layer, W prevents Au from dewetting regardless of Au film thickness. Moreover, regular pattern formation of Au-WO3 nanoparticles is observed at high temperature demonstrating how bilayer thin film dewetting can create unique nanostructure arrangements. (C) 2016 Author(s).