We experimentally observe quantum confinement states in bulk MoS₂ by using angle-resolved photoemission spectroscopy (ARPES). The band structure at the Γ̅ point reveals quantum well states (QWSs) linked to vertical quantum confinement of the electrons, confirmed by the absence of dispersion in k_z and a strong intensity modulation with the photon energy. Notably, the binding energy dependence of the QWSs versus n does not follow the quadratic dependence of a two-dimensional electron gas. Instead, a linear behavior is observed that is consistent with a parabolic-like quantum well. This confinement arises from the mechanical exfoliation preparation method, which leads to the detachment of a multilayer stack from the underlying bulk. This is confirmed by density functional theory (DFT) calculations. The quantum confinement in bulk-like MoS₂ not only offers the opportunity to explore intersubband transitions to exploit optical properties but also provides a means to study fundamental quantum phenomena in multilayer stacks of different thicknesses.

中文翻译：

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块体 MoS2 中的垂直量子约束


我们使用角度分辨光电子能谱 （ARPES） 实验观察体 MoS₂ 中的量子约束态。Γ̅ 点的能带结构揭示了与电子的垂直量子限制相关的量子阱态 （QWS），这可以通过没有 k_z 色散和光子能量的强强度调制来证实。值得注意的是，QWs 与 n 的结合能依赖性并不遵循二维电子气体的二次依赖性。相反，观察到与类似抛物线的量子井一致的线性行为。这种限制源于机械去角质制备方法，该方法导致多层堆栈与底层块体分离。密度泛函理论 （DFT） 计算证实了这一点。块状 MoS₂ 中的量子限制不仅为探索子带间跃迁以利用光学特性提供了机会，而且还提供了一种研究不同厚度的多层堆栈中基本量子现象的方法。