Schottky–Mott limit in graphene inserted 2D semiconductor–metal interfaces

Abstract

The insertion of a graphene (or h-BN) layer in a two-dimensional (2D) MoS2–metal interface to de-pin the Fermi level has been a common strategy in experiments. Recently, however, the 2D material space has expanded much beyond transition metal dichalcogenides, and it is not clear if the same strategy will work for other materials. Here, we select a family of twelve emerging, commercially available 2D semiconductors with the work function range of 3.8–6.1 eV and study their interfaces with metals in the presence and absence of the graphene buffer layer. Using the density functional theory, we show that the graphene buffer layer preserves the ideal Schottky–Mott rule to a great extent when the interfaces are made with Ag and Ti. However, the h-BN buffer layer does not yield a similar performance since its electrons are not as localized as graphene. It is further observed that even graphene is not very effective in preserving the ideal Schottky–Mott rule while interfacing with high work function metals (Au, Pd, and Pt). The quantum chemical insights presented in this paper could aid in the design of high-performance electronic devices with low contact resistance based on newly developed 2D materials.