Precise determination of the layer number (N) of hexagonal boron nitride (hBN) is crucial for its integration with other layered materials in applications such as ferroelectric devices and moiré potential modulation. We present a nondestructive method to accurately identify N, combining optical contrast analysis with second harmonic generation (SHG) measurements. By studying the flakes on 90 nm thick SiO₂/Si substrates, we demonstrate that red-filtered optical images provide a clear contrast step in N with an uncertainty of ±1 layer, while SHG measurements further reduce the error by distinguishing even and odd layers. We also introduce a real-time detection technique to identify monolayer and few-layer hBN, improving flake identification efficiency. Given the growing interest in twisted hBN interfaces and their integration in van der Waals heterostructures, this method offers a practical approach for future studies.

中文翻译：

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使用光学表征准确测定六方氮化硼的层数


精确测定六方氮化硼 （hBN） 的层数 （N） 对于在铁电器件和莫尔电位调制等应用中与其他层状材料的集成至关重要。我们提出了一种将光学对比度分析与二次谐波产生 （SHG） 测量相结合的无损方法来准确识别 N。通过研究 90 nm 厚的 SiO₂/Si 衬底上的薄片，我们证明红色过滤光学图像在 N 中提供了清晰的对比步骤，不确定性为 ±1 层，而 SHG 测量通过区分偶数层和奇数层进一步降低了误差。我们还引入了一种实时检测技术来识别单层和少层 hBN，从而提高薄片识别效率。鉴于人们对扭曲 hBN 界面及其在范德华异质结构中的集成越来越感兴趣，该方法为未来的研究提供了一种实用的方法。