The Schottky–Mott Rule Expanded for Two-Dimensional Semiconductors: Influence of Substrate Dielectric Screening

High Resolution Image Download MS PowerPoint Slide A comprehensive understanding of the energy level alignment mechanisms between two-dimensional (2D) semiconductors and electrodes is currently lacking, but it is a prerequisite for tailoring the interface electronic properties to the requirements of device applications. Here, we use angle-resolved direct and inverse photoelectron spectroscopy to unravel the key factors that determine the level alignment at interfaces between a monolayer of the prototypical 2D semiconductor MoS 2 and conductor, semiconductor, and insulator substrates. For substrate work function (Φ sub ) values below 4.5 eV we find that Fermi level pinning occurs, involving electron transfer to native MoS 2 gap states below the conduction band. For Φ sub above 4.5 eV, vacuum level alignment prevails but the charge injection barriers do not strictly follow the changes of Φ…