Designing CMOS compatible efficient ohmic contacts to WSi2N4via surface-engineered Mo2B monolayer electrodes

Abstract

Forming ohmic contacts between metals and semiconductors is critical to achieving high-performance and energy-efficient electronics. Here we investigate the interface properties of WSi₂N₄ contacted by Mo₂B, O-modified Mo₂B (Mo₂BO₂) and OH-modified Mo₂B (Mo₂B(OH)₂) nanosheets using density functional theory simulations. We show that WSi₂N₄ and Mo₂B form n-type Schottky contacts with barrier heights that are robust against external electric fields. In contrast, functionalizing Mo₂B with O and OH causes the work function to energetically down- and up-shift significantly, thus forming both n-type and p-type ohmic contacts with WSi₂N₄, respectively. The possibility of achieving both p-type and n-type ohmic contacts immediately suggests the role of surface-engineered Mo₂B as a key enabler towards WSi₂N₄-based complementary metal–oxide–semiconductor (CMOS) device technology in which both n-type and p-type devices are needed. We further demonstrate the emergence of quasi-ohmic contact with ultralow lateral Schottky barrier and zero vertical interfacial tunneling barriers in Mo₂B(OH)₂-contacted WSi₂N₄ – a feature rarely found in other 2D/2D metal/semiconductor contacts, thus demonstrating surface-engineered Mo₂B as a promising electrode to WSi₂N₄ with high charge injection efficiency. These results offer design insights useful for the development of high-performance 2D semiconductor CMOS device technology.