Atomically thin transition metal dichalcogenides (TMDCs) are promising candidates for implementation in next generation semiconducting devices, for which laterally homogeneous behavior is needed. Here, we study the electronic structure of atomically thin exfoliated WSe₂, a prototypical TMDC with large spin–orbit coupling, by photoemission electron microscopy, electron energy-loss spectroscopy, and density functional theory. We resolve the inhomogeneities of the doping level by the varying energy positions of the valence band. There appear to be different types of inhomogeneities that respond differently to electron doping, introduced by potassium intercalation. In addition, we find that the doping process itself is more complex than previously anticipated and entails a distinct orbital and thickness dependence that needs to be considered for effective band engineering. In particular, the density of selenium vs tungsten states depends on the doping level, which leads to changes in the optical response beyond increased dielectric screening. Our work gives insight into the inhomogeneity of the electron structure of WSe₂ and the effects of electron doping, provides microscopic understanding thereof, and improves the basis for property engineering of 2D materials.

中文翻译：

---

原子薄WSe2中电子结构变化的光谱显微镜测量

原子薄的过渡金属二硫化碳（TMDC）是有希望在下一代半导体器件中实现的候选材料，而下一代半导体器件需要横向均匀的性能。在这里，我们研究原子薄剥离WSe ₂的电子结构是通过光发射电子显微镜，电子能量损失谱和密度泛函理论，具有大自旋轨道耦合的典型TMDC。我们通过改变价带的能量位置来解决掺杂水平的不均匀性。似乎存在不同类型的不均匀性，它们对通过钾插层引入的电子掺杂的反应不同。此外，我们发现掺杂过程本身比以前预期的要复杂，并且需要明确的轨道和厚度依赖性，有效的频带工程需要考虑这一点。特别地，硒对钨态的密度取决于掺杂水平，这导致除了增加介电屏蔽之外的光学响应变化。_通过图2以及电子掺杂的影响，可以对其进行微观了解，并改善2D材料特性工程的基础。