Inhomogeneous Charge Carrier Density in Wafer-Scale MoS ₂ Caused by Locally Varying Substrate Doping

Metal-organic chemical vapor deposition is the most promising approach to synthesizing wafer-scale transition metal dichalcogenide (TMDC) monolayers, a key requirement for implementing TMDCs in future electronics. Hereby, the control of doping caused by either defect formation or remote doping from the substrate or the environment is a main challenge. In this work, we reveal local variations of the charge carrier density on wafer-scale MoS₂ monolayers with crystalline domains larger than 50 μm, grown via MOCVD on c-plane sapphire. The charge variations occur on a submicrometer length scale, altering the ratio between trion and neutral exciton and the MoS₂ working function, respectively. We identified sapphire surface anomalies to be responsible for locally varying substrate doping, a hypothesis that is confirmed by a dedicated transfer experiment of MoS₂ onto a Si/SiO₂ substrate.