Yip Kevin, Cui Teng, Filleter Tobin
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada.
Rev Sci Instrum. 2020 Jun 1;91(6):063703. doi: 10.1063/5.0004628.
Photothermal excitation of the cantilever for use in subsurface imaging with atomic force microscopy was compared against traditional piezoelectric excitation. Photothermal excitation alleviates issues commonly found in traditional piezoelectrics such as spurious resonances by producing clean resonance peaks through direct cantilever excitation. A calibration specimen consisting of a 3 × 3 array of holes ranging from 200 to 30 nm etched into silicon and covered by graphite was used to compare these two drive mechanisms. Photothermal excitation exhibited a signal-to-noise ratio as high as four times when compared to piezoelectric excitation, utilizing higher eigenmodes for subsurface imaging. The cleaner and sharper resonance peaks obtained using photothermal excitation revealed all subsurface holes down to 30 nm through 135 nm of graphite. In addition, we demonstrated the ability of using photothermal excitation to detect the contact quality variation and evolution at graphite-polymer interfaces, which is critical in graphene-based nanocomposites, flexible electronics, and functional coatings.
将用于原子力显微镜地下成像的悬臂梁光热激发与传统的压电激发进行了比较。光热激发通过直接激发悬臂梁产生清晰的共振峰，从而缓解了传统压电激发中常见的问题，如杂散共振。使用一个校准样本，该校准样本由蚀刻在硅中并覆盖有石墨的3×3阵列的孔组成，这些孔的尺寸从200纳米到30纳米不等，用于比较这两种驱动机制。与压电激发相比，光热激发的信噪比高达四倍，利用更高的本征模式进行地下成像。使用光热激发获得的更清晰、更尖锐的共振峰揭示了透过135纳米石墨层直至30纳米的所有地下孔洞。此外，我们展示了利用光热激发检测石墨 - 聚合物界面处接触质量变化和演变的能力，这在基于石墨烯的纳米复合材料、柔性电子器件和功能涂层中至关重要。
