Physical mechanisms of megahertz vibrations and nonlinear detection in ultrasonic force and related microscopies
Physical mechanisms of megahertz vibrations and nonlinear detection in ultrasonic force and related microscopies
复制标题
DOI：
10.1063/1.4871077
复制
发表时间：
2014-04-14
影响因子：
3.2
通讯作者：
Kolosov, O. V.
中科院分区：
文献类型：
--
作者：
Bosse, J. L.;Tovee, P. D.;Kolosov, O. V.
在原子力显微镜（AFM）中使用MHz频率的高频（HF）振动将纳米级特性映射到视频速率，允许使用悬臂梁动力学来映射刚性材料的纳米机械特性，感测纳米结构中的μ s时间尺度现象，并能够以纳米级分辨率检测亚表面特征。所有这些方法都严重依赖于与所研究的样品接触的AFM悬臂梁的通常较差的表征HF行为、压电换能器的空间和频率响应以及探针和试样之间的超声振动的传递。特别关注超声力显微镜（UFM），这项工作也适用于波导UFM，外差力显微镜，近场全息显微镜，所有的方法，利用非线性尖端表面力在高频率的相互作用。利用自动多维测量，光谱UFM（sUFM）的介绍，调查一系列常见的实验参数，包括压电换能器的激励频率，探测位置，超声波振幅，悬臂梁的几何形状，弹簧常数，和法向力。与这些因素中的每一个的影响的研究一致，数据丰富的sUFM特征允许基于超声AFM的测量的有效优化，导致使用具有较低基本谐振的较长杠杆的最佳实践建议，同时增加HF压电致动器的中心频率，并且仅比较几μ m（2）量级的区域内的结果，除非直接校准或与成像区域内标准进行比较。不同的材料，如硅，铬，和光刻胶进行了具体的研究。因此，这项工作提供了必要的洞察力，可靠地使用MHz的振动与AFM，并提供直接的证据证实的现象，如敏感性粘附，减少摩擦，某些超声条件下，和特别的好处UFM和相关方法的纳米尺度映射的刚性材料。(C)2014 AIP出版有限责任公司。
Use of high frequency (HF) vibrations at MHz frequencies in Atomic Force Microscopy (AFM) advanced nanoscale property mapping to video rates, allowed use of cantilever dynamics for mapping nanomechanical properties of stiff materials, sensing mu s time scale phenomena in nanostructures, and enabled detection of subsurface features with nanoscale resolution. All of these methods critically depend on the generally poor characterized HF behaviour of AFM cantilevers in contact with a studied sample, spatial and frequency response of piezotransducers, and transfer of ultrasonic vibrations between the probe and a specimen. Focusing particularly on Ultrasonic Force Microscopy (UFM), this work is also applicable to waveguide UFM, heterodyne force microscopy, and near-field holographic microscopy, all methods that exploit nonlinear tip-surface force interactions at high frequencies. Leveraging automated multidimensional measurements, spectroscopic UFM (sUFM) is introduced to investigate a range of common experimental parameters, including piezotransducer excitation frequency, probed position, ultrasonic amplitude, cantilever geometry, spring constant, and normal force. Consistent with studies of influence of each of these factors, the data-rich sUFM signatures allow efficient optimization of ultrasonic-AFM based measurements, leading to best practices recommendations of using longer cantilevers with lower fundamental resonance, while at the same time increasing the central frequency of HF piezo-actuators, and only comparing results within areas on the order of few mu m(2) unless calibrated directly or compared with in-the-imaged area standards. Diverse materials such as Si, Cr, and photoresist are specifically investigated. This work thereby provides essential insight into the reliable use of MHz vibrations with AFM and provides direct evidence substantiating phenomena such as sensitivity to adhesion, diminished friction for certain ultrasonic conditions, and the particular benefit of UFM and related methods for nanoscale mapping of stiff materials. (C) 2014 AIP Publishing LLC.