Two-dimensional materials and their heterostructures have significant potential for future developments in materials science and optoelectronics due to their unique properties. However, their fabrication and transfer process often introduce impurities and contaminants that degrade their intrinsic qualities. To address this issue, current atomic force microscopy (AFM) probe contact mode methods provide a solution by allowing in situ cleaning and real-time observation of the nanoscale cleaning process. Nevertheless, existing pyramidal probes may scratch surfaces and damage heterostructures during force application. Therefore, we proposed a method based on the nano-spherical probe contact mode to clean residual and polymer contamination for minimum damage cleaning of MoS₂/hBN substrates. Comparative experiments with pyramidal probes in 2DM morphology and photoluminescence (PL) have shown that nano-spherical probes are exceptionally effective in cleaning bubbles of various sizes, compared to uncleaned MoS₂, where PL full width at half maximum (FWHM) averages 0.115 eV, nano-spherical probes reduce it by 30% to 0.08 eV. Pyramidal probes, however, only clean smaller bubbles and leave residuals in larger ones, resulting in less optimal PL mapping data with values in both the 0.09 eV and 0.0115 eV regions. We also collected the standard deviation of the FWHM data points for the uncleaned region and the regions cleaned by the pyramidal and nano-spherical probes, which were 0.02773, 0.01895, and 0.00531, respectively. Notably, the standard deviation of the FWHM in the nano-spherical probe-cleaned region is only 28% of that in the pyramidal probe-cleaned region. Then, increasing the applied force leads to damage in the crystal structure, resulting in potential inconsistencies across different areas, as evidenced by KPFM and SEM observations. In contrast, nano-spherical probes demonstrate a uniform potential in KPFM and consistently maintain a smooth surface morphology in SEM throughout the process. This approach highlights the potential of nano-spherical probes to advance minimum-damage cleaning techniques in 2D material research and applications.

中文翻译：

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基于 Nano 球形尖端的平滑，对 2D van der Waals 异质结构的损伤最小


二维材料及其异质结构由于其独特的性能，在材料科学和光电子学的未来发展中具有巨大的潜力。然而，它们的制造和转移过程通常会引入杂质和污染物，从而降低其内在品质。为了解决这个问题，当前的原子力显微镜 （AFM） 探针接触模式方法提供了一种解决方案，它允许原位清洁和实时观察纳米级清洁过程。然而，现有的金字塔形探针在施加力时可能会划伤表面并损坏异质结构。因此，我们提出了一种基于纳米球形探针接触模式的方法来清洁残留物和聚合物污染，以最大限度地减少对 MoS₂/hBN 衬底的损伤清洗。在 2DM 形态和光致发光 （PL） 中与金字塔形探针的比较实验表明，纳米球形探针在清洁各种大小的气泡方面非常有效，与未清洁的 MoS₂ 相比，其中 PL 半峰全宽 （FWHM） 平均为 0.115 eV，纳米球形探针将其降低 30% 至 0.08 eV。然而，金字塔形探针只能清理较小的气泡，并在较大的气泡中留下残差，从而导致 0.09 eV 和 0.0115 eV 区域的值不太理想的 PL 映射数据。我们还收集了未清洁区域和金字塔形和纳米球形探针清洁区域的 FWHM 数据点的标准差，分别为 0.02773、0.01895 和 0.00531。值得注意的是，纳米球形探针清洁区域中 FWHM 的标准偏差仅为金字塔形探针清洁区域的 28%。 然后，增加施加的力会导致晶体结构受损，从而导致不同区域的潜在不一致，KPFM 和 SEM 观察证明了这一点。相比之下，纳米球形探针在 KPFM 中表现出均匀的电位，并在整个过程中在 SEM 中始终保持光滑的表面形态。这种方法突出了纳米球形探针在 2D 材料研究和应用中推进最小损伤清洁技术的潜力。