Ultrasound atomic force microscopy (AFM) has received considerable interest due to its subsurface imaging capabilities, particularly for nanostructure imaging. The local contact stiffness variation due to the presence of a subsurface feature is the origin of the imaging contrast. Several research studies have demonstrated subsurface imaging capabilities with promising resolution. However, there is limited literature available about the definition of spatial resolution in subsurface AFM. The changes in contact stiffness and their link to the subsurface resolution are not well understood. We propose a quantitative approach to assess the resolution in subsurface AFM imaging. We have investigated the influences of several parameters of interest on the lateral resolution. The quantification of the subsurface feature size can be based on threshold criteria (full width at half maximum and Rayleigh criteria). Simulations and experimental measurements were compared, revealing that the optimal choice of parameter settings for surface topography AFM is suboptimal for subsurface AFM imaging.

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关于次表面原子力显微镜的分辨率及其对次表面特征尺寸的影响

超声原子力显微镜 (AFM) 因其亚表面成像能力，特别是纳米结构成像而受到了极大的关注。由于存在地下特征而导致的局部接触刚度变化是成像对比度的起源。几项研究表明，具有良好分辨率的地下成像能力。然而，关于地下原子力显微镜空间分辨率定义的文献有限。接触刚度的变化及其与地下分辨率的联系尚不清楚。我们提出了一种定量方法来评估地下 AFM 成像的分辨率。我们研究了几个感兴趣的参数对横向分辨率的影响。地下特征尺寸的量化可以基于阈值标准（半高全宽和瑞利标准）。对模拟和实验测量进行了比较，揭示了表面形貌 AFM 参数设置的最佳选择对于地下 AFM 成像来说不是最佳的。