Because synthetic 2D materials are generally stabilized by interfacial coupling to growth substrates, direct probing of interfacial phenomena is critical for understanding their nanoscale structure and properties. Using field-emission resonance spectroscopy with an ultrahigh vacuum scanning tunneling microscope, we reveal Stark-shifted image-potential states of the v_1/6 and v_1/5 borophene polymorphs on Ag(111) with long lifetimes, suggesting high borophene lattice and interface quality. These image-potential states allow the local work function and interfacial charge transfer of borophene to be probed at the nanoscale and test the widely employed self-doping model of borophene. Supported by apparent barrier height measurements and density functional theory calculations, electron transfer doping occurs for both borophene phases from the Ag(111) substrate. In contradiction with the self-doping model, a higher electron transfer doping level occurs for denser v_1/6 borophene compared to v_1/5 borophene, thus revealing the importance of substrate effects on borophene electron transfer.

中文翻译：

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硼砂型多晶型物的图像势态和电子转移掺杂的纳米级探测。

因为合成2D材料通常通过与生长基质的界面耦合来稳定，所以界面现象的直接探测对于理解其纳米级结构和特性至关重要。使用场发射共振光谱学和超高真空扫描隧道显微镜，我们揭示了v _1/6和v _1/5的斯塔克位移像_势态Ag（111）上的硼烷多晶型物具有较长的寿命，表明硼烷的晶格和界面质量较高。这些图像势态允许在纳米级探测硼苯的局部功函数和界面电荷转移，并测试广泛使用的硼苯的自掺杂模型。在明显的势垒高度测量和密度泛函理论计算的支持下，来自Ag（111）衬底的两个硼苯相均发生电子转移掺杂。与自掺杂模型相反，与v _1/5硼苯相比，密度更高的v _1/6硼苯发生更高的电子转移掺杂水平，因此揭示了衬底效应对硼苯电子转移的重要性。