Abstract Ag(111) islands nucleate on a one-monolayer-thick wetting layer with an aperiodic arrangement of Ag atoms on a Si(111)7 × 7 substrate. Recent X-ray diffraction studies have revealed that the Ag wetting layer is crystallized under the Ag islands. We examined whether this wetting layer contributes to the formation of the quantum-well states (QWSs) in the Ag(111) islands by measuring the relation between the energy E of the QWSs and the height of the Ag islands w from the wetting layers using scanning tunneling microscopy and dz/dV spectroscopy. The E-w relation on the Si(111)7 × 7 substrate was found to be shifted by plus one monolayer relative to that for Ag islands on the Si(111)√3 × √3-B substrate, for which nucleation occurs directly on the substrate without the involvement of a wetting layer. The subsurface B atoms on the Si(111)√3 × √3-B substrate were confirmed not to be responsible for the shift in the E-w relation through density functional theory calculations. These results indicate that the wetting layer was incorporated into the Ag(111) islands and contributed to the formation of the QWSs as the bottom part of the crystalline Ag(111) layers.

中文翻译：

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Si(111)7 × 7 衬底上超薄 Ag(111) 薄膜中受限电子的有效量子阱宽度

摘要 Ag(111) 岛在单层厚的润湿层上成核，在 Si(111)7 × 7 衬底上具有非周期性排列的 Ag 原子。最近的 X 射线衍射研究表明，Ag 润湿层在 Ag 岛下方结晶。我们通过测量 QWS 的能量 E 与 Ag 岛距润湿层的高度 w 之间的关系，检查了该润湿层是否有助于 Ag(111) 岛中量子阱态 (QWS) 的形成。扫描隧道显微镜和 dz/dV 光谱。发现 Si(111)7 × 7 衬底上的 Ew 关系相对于 Si(111)√3 × √3-B 衬底上的 Ag 岛的 Ew 关系增加了一个单层，其中成核直接发生在不涉及润湿层的基材。通过密度泛函理论计算，证实 Si(111)√3 × √3-B 衬底上的亚表面 B 原子不是 Ew 关系偏移的原因。这些结果表明润湿层被结合到 Ag(111) 岛中并有助于形成 QWSs 作为晶体 Ag(111) 层的底部。