The role of the metal in metal/MoS2 and metal/Ca2N/MoS2 interfaces

Abstract

While transition-metal diachalcogenides like MoS₂ are promising materials for future generations of miniaturized semiconductor devices, high contact resistance of the metal/MoS₂ junction is presently the largest barrier to their widespread adoption. Monolayer electrides, known as electrenes, are theorized to lower contact resistance when inserted at junctions of metals and 2D transition-metal dichalcogenide semiconductors through electron donation. A recent theoretical survey of di-alkaline earth pnictogen electrenes in copper/electrene/MoS₂ interfaces and gold/electrene/MoS₂ interfaces recommended Ca₂N for this application owing to its high surface charge. In this work, we will investigate the role of the metal in metal/Ca₂N/MoS₂ heterostructures using dispersion-corrected density-functional theory. The role of the metal in metal/MoS₂ interfaces will also be considered as a point of reference. Our results show that the metal plays a major role in determining the interface characteristics of metal/MoS₂ interfaces, but only a minor one in those of metal/Ca₂N/MoS₂ interfaces. We also demonstrate a shrinking of the MoS₂ band gap induced by interfaces with large charge transfer and poor honeycomb overlap of the component materials. Going forward, the choice of contact metals in metal/Ca₂N/MoS₂ interfaces can be one of sustainability and compatibility in semiconductor device manufacturing.