Moiré patterns with a superlattice potential can be formed by vertically stacking two layered materials with a relative twist or lattice constant mismatch. In transition metal dichalcogenide-based systems, the moiré potential landscape can trap interlayer excitons (IXs) at specific atomic registries. Here, we report that spatially isolated trapped IXs in a molybdenum diselenide/tungsten diselenide heterobilayer device provide a sensitive optical probe of carrier filling in their immediate environment. By mapping the spatial positions of individual trapped IXs, we are able to spectrally track the emitters as the moiré lattice is filled with excess carriers. Upon initial doping of the heterobilayer, neutral trapped IXs form charged IXs (IX trions) uniformly with a binding energy of ~7 meV. Upon further doping, the empty superlattice sites sequentially fill, creating a Coulomb staircase: stepwise changes in the IX trion emission energy due to Coulomb interactions with carriers at nearest-neighbour moiré sites. This non-invasive, highly local technique can complement transport and non-local optical sensing techniques to characterize Coulomb interaction energies, visualize charge correlated states, or probe local disorder in a moiré superlattice.

具有超晶格势能的莫尔图案可以通过垂直堆叠具有相对扭曲或晶格常数失配的两层材料来形成。在基于过渡金属二硫化物的系统中，莫尔电位景观可以在特定的原子登记处捕获层间激子 (IX)。在这里，我们报告了在二硒化钼/二硒化钨异质双层器件中空间隔离的捕获 IX 提供了一种灵敏的光学探针，用于在其直接环境中填充载流子。通过映射单个被捕获 IX 的空间位置，我们能够在莫尔晶格充满过量载流子时对发射器进行光谱跟踪。在异质双层的初始掺杂后，中性捕获的 IXs 以约 7 meV 的结合能均匀地形成带电 IXs（IX trions）。进一步掺杂后，空的超晶格位点依次填充，形成库仑阶梯：由于库仑与最近邻莫尔位点的载流子相互作用，IX trion 发射能量逐步变化。这种非侵入性、高度局部化的技术可以补充传输和非局部光学传感技术，以表征库仑相互作用能量、可视化电荷相关状态或探测莫尔超晶格中的局部无序。