Ohnsorg Monica L, Beaudoin Christopher K, Anderson Mary E
Department of Chemistry, Hope College, 35 E. 12th Street, Holland, Michigan 49422, United States.
Langmuir. 2015 Jun 9;31(22):6114-21. doi: 10.1021/acs.langmuir.5b01333. Epub 2015 May 28.
Thin films can integrate the versatility and great potential found in the emerging field of metal-organic frameworks directly into device architectures. For fabrication of smart interfaces containing surface-anchored metal-organic frameworks, it is important to understand how the foundational layers form to create the interface between the underlying substrate and porous framework. Herein, the formation and morphology of the first ten cycles of film deposition are investigated for the well-studied HKUST-1 system. Effects of processing variables, such as deposition temperature and substrate quality, are studied. Sequences of scanning probe microscopy images collected after cycles of alternating solution-phase deposition reveal the formation of a discontinuous surface with nucleating and growing crystallites consistent with a Volmer-Weber growth mechanism. Quantitative image analysis determines surface roughness and surface coverage as a function of deposition cycles, producing insight regarding growth and structure of foundational film layers. For carboxylic acid terminated self-assembled monolayers on gold, preferred crystal orientation is influenced by deposition temperature with crystal growth along [100] observed at 25 °C and [111] favored at 50 °C. This difference in crystal orientation results in reduced surface roughness and increased surface coverage at 50 °C. To properly fabricate and fully determine the potential of this material for industrial applications, fundamental understanding of film formation is crucial.
薄膜可以将金属有机框架这一新兴领域的多功能性和巨大潜力直接整合到器件架构中。对于包含表面锚定金属有机框架的智能界面的制备而言，了解基础层如何形成以在底层基板和多孔框架之间创建界面非常重要。在此，针对研究充分的HKUST-1体系，研究了薄膜沉积前十轮循环的形成过程和形态。研究了诸如沉积温度和基板质量等工艺变量的影响。在交替溶液相沉积循环后收集的扫描探针显微镜图像序列揭示了形成了一个不连续表面，其中有与伏尔默-韦伯生长机制一致的成核和生长微晶。定量图像分析确定了表面粗糙度和表面覆盖率与沉积循环的函数关系，从而深入了解基础薄膜层的生长和结构。对于金表面的羧酸封端自组装单分子层，晶体择优取向受沉积温度影响，在25°C时观察到沿[100]方向的晶体生长，而在50°C时则有利于[111]方向。这种晶体取向的差异导致在50°C时表面粗糙度降低且表面覆盖率增加。为了正确制备并充分确定这种材料在工业应用中的潜力，对薄膜形成的基本理解至关重要。
