Study of structural morphology of electrodeposited Ni thin film on Au(111) substrate.

我们的中心目标是了解多晶电沉积金属薄膜的微观结构和表面形态(晶界、生长速度)。电沉积金属薄膜具有多种用途，其中微结构和表面形态对其性能起着关键作用，从装饰性和耐腐蚀性涂层到超大规模集成电路中的连接器。耐电性和耐化学性也可以通过微观结构来控制。尤其是电沉积镍，由于其众多的用途和独特的性能，在电沉积多晶金属薄膜中具有特殊的吸引力。镍涂层被广泛用于提高耐腐蚀性和耐磨性，其机械性能使其特别适用于电沉积制备的微电子机械系统(MEMS)。镍也引起了人们的极大兴趣，因为尽管镍与铜具有面心立方结构，但它的研究引入了新的特征。在室温下，镍的原子迁移率明显低于铜，这是由扩散系数来评价的，扩散系数抑制了晶粒的粗化，导致了更明显的柱状织构，而且与铜不同的是，镍的沉积通常发生在析氢重要的电位下，这可以通过表面吸附强烈地改变织构。然而，尽管它们意义重大，是什么决定了多晶电沉积金属薄膜的微观结构和表面形态，这个问题在很大程度上仍然没有解决。生长驱动的晶粒粗化或缺陷处新晶形核的详细机制仍需注意了解。我们的项目将利用高速原子力显微镜(HS-AFM)和Xe等离子体聚焦离子束(等离子FIB)球磨这两项主要技术进步来克服这一实验瓶颈。我们将研究电沉积镍薄膜的微观结构和表面形貌之间的关系。原位HS-AFM将在生长过程中提供高分辨率的表面形貌，而等离子体FIB将被用于对所得到的薄膜进行切片，以通过电子背散射衍射(EBSD)来表征不同深度处的颗粒结构。结合HS-AFM和EBSD数据将使我们能够将表面结构演变与同一区域薄膜沉积后的微结构相关联，并将使用异常快速和方便的测量技术来实现这一点。我们关联的整体和表面数据将为定量研究提供电沉积的关键方面。例如，在现实的电沉积条件下，晶体取向和生长速度之间的关系从未在实验上建立过，尽管它是理解多晶生长的基础。通过比较连续的HS-AFM图像，我们可以测量局部生长速度，并将它们与基晶的取向相关联。通过改变电解液的组成，我们可以观察到不同的吸附剂对取向相关生长速率的影响，从而为添加剂控制薄膜的形貌和织构提供了有益的见解。该项目属于EPSRC物理科学研究领域。

Our central aim is to understand the microstructure and surface morphology (grain boundaries, growth rate) of polycrystalline electrodeposited metal films. Electrodeposited metal films have multiple applications where microstructure and surface morphology play key role to their performance, from ornamental and corrosion-resistant coatings to connectors in ultra-large-scale integrated circuits. Electrical and chemical resistance can also be controlled by microstructures. Specially, electrodeposited Ni has special attraction in electrodeposited polycrystalline metal thin films because of its many applications and unique features. Ni coatings are widely used to improve corrosion and wear resistance, and its mechanical properties make Ni especially useful for micro-electromechanical systems (MEMS) fabricated by electrodeposition. Ni is also of great interest because although Ni shares the fcc crystal structure with Cu, its study introduces new features. Atomic mobilities are significantly lower for Ni than Cu at room temperature which was critically assessed by diffusion coefficient, which suppresses grain coarsening and leads to a more pronounced columnar texture, and unlike Cu, Ni deposition usually takes place at potentials where hydrogen evolution is important, which can strongly modify the texture via surface adsorption. However, despite their significance, the problem of what determines the microstructure and surface morphology of a polycrystalline electrodeposited metal film is still largely unsolved. The detailed mechanism for growth driven grain coarsening or nucleation of new grains at defect still need attention to understand. Our project will overcome this experimental bottleneck by exploiting two major technical advances, high speed atomic force microscopy (HS-AFM) and Xe plasma focussed ion beam (plasma FIB) milling. We shall investigate the relation between microstructure and surface morphology of Ni electrodeposited thin film. In-situ HS-AFM will provide high-resolution surface topography during growth, while plasma FIB milling will be used to section the resulting film to characterize the grain structure at different depths by electron backscatter diffraction (EBSD). Combining HS-AFM and EBSD data will enable us to correlate surface structure evolution with the post-deposition microstructure of the same area of film and to will do so using exceptionally rapid and convenient measurement techniques. Our linked bulk and surface data will provide key aspects of electrodeposition to quantitative study. For example, the relation between crystallographic alignment and growth rate has never been established experimentally under realistic electrodeposition conditions, despite it being fundamental to understanding polycrystalline growth. By comparing successive HS-AFM images we can measure local growth rates and correlate them with the orientations of the basal grains. By changing the electrolyte composition, we shall be able to observe the effect of different adsorbates on orientation-dependent growth rate, providing beneficial insight into the role of additives to control film morphology and texture. This project falls within the EPSRC Physical science research area.