School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, United States of America.
Nanotechnology. 2018 Oct 5;29(40):405702. doi: 10.1088/1361-6528/aacfdc. Epub 2018 Jun 28.
Second harmonic Kelvin probe force microscopy is a robust mechanism for subsurface imaging at the nanoscale. Here we exploit resonance-enhanced detection as a way to boost the subsurface contrast with higher force sensitivity using lower bias voltages, in comparison to the traditional off-resonance case. In this mode, the second harmonic signal of the electrostatic force is acquired at one of the eigenmode frequencies of the microcantilever. As a result, high resolution subsurface images are obtained in a variety of nanocomposites. To further understand the subsurface imaging detection upon electrostatic forces, we use a finite element model that approximates the geometry of the probe and sample. This allows the investigation of the contrast mechanism, the depth sensitivity and lateral resolution depending on tip-sample properties.
二次谐波 Kelvin 探针力显微镜是一种强大的纳米尺度下的亚表面成像机制。在这里，我们利用共振增强检测来提高亚表面对比度，与传统的非共振情况相比，使用更低的偏置电压即可实现更高的力灵敏度。在这种模式下，微悬臂的本征模式频率之一会采集到静电力的二次谐波信号。结果，在各种纳米复合材料中都获得了高分辨率的亚表面图像。为了进一步了解静电力作用下的亚表面成像检测，我们使用了一个有限元模型来近似探针和样品的几何形状。这使得我们可以根据针尖-样品的特性来研究对比度机制、深度灵敏度和横向分辨率。
