Numerical simulations for a quantitative analysis of AFM electrostatic nanopatterning on PMMA by Kelvin force microscopy
Numerical simulations for a quantitative analysis of AFM electrostatic nanopatterning on PMMA by Kelvin force microscopy
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DOI：
10.1088/0957-4484/21/22/225706
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发表时间：
2010-06-04
期刊：
影响因子：
3.5
通讯作者：
Melin, T.
中科院分区：
文献类型：
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作者：
Palleau, E.;Ressier, L.;Melin, T.
利用原子力显微镜（AFM）对驻极体薄膜进行静电纳米图像化已经成为在表面上定向组装纳米物体的另一种有效工具。基于原子力显微镜（afm）的开尔文力显微镜（KFM）可以对这种电荷模式进行高分辨率的电荷成像。然而，由于尖端锥和扫描探针悬臂引起的侧电容效应，KFM表面电位映射的定量分析并非微不足道。在本文中，我们开发了考虑这些伪影的KFM测量的数值模拟，以便估计由AFM写入聚甲基丙烯酸甲酯（PMMA）薄膜的方形电荷模式（标称尺寸从100 nm到10 μ m）的实际表面电荷密度。这项工作表明，在我们的条件下，这种电荷模式的表面电荷密度在1.5 x 10（-3）和3.8 x 10(-3) cm（-2）之间，这取决于假设的注入电荷深度。这些结果对于量化由这种电荷模式产生的实际电场以及负责将纳米物体定向组装到这些静电阱上的静电力至关重要。
Electrostatic nanopatterning of electret thin films by atomic force microscopy (AFM) has emerged as an alternative efficient tool for the directed assembly of nano-objects on surfaces. High-resolution charge imaging of such charge patterns can be performed by AFM-based Kelvin force microscopy (KFM). Nevertheless, quantitative analysis of KFM surface potential mappings is not trivial because of side-capacitance effects induced by the tip cone and the cantilever of the scanning probe.In this paper, we developed numerical simulations of KFM measurements taking into account these artifacts, so as to estimate the actual surface charge density of square charge patterns (nominal sizes ranging from 100 nm to 10 mu m) written by AFM into polymethylmethacrylate (PMMA) thin films. This work revealed that, under our conditions, such charge patterns exhibit a surface charge density between 1.5 x 10(-3) and 3.8 x 10(-3) C m(-2), depending on the assumed depth of injected charges. These results are crucial to quantify the actual electric field generated by such charge patterns and thus the electrostatic forces responsible for the directed assembly of nano-objects onto these electrostatic traps.