Lateral Chemical Bonding in Two-Dimensional Transition-Metal Dichalcogenide Metal/Semiconductor Heterostructures

Discovering better materials for electronic devices is important for technological advancements. One of the most promising materials are transition-metal dichalcogenides (TMDCs) due to their ability to form two-dimensional structures with diverse compositions. Recently, experimental breakthroughs were demonstrated for all two-dimensional transistors that contain a semiconducting TMDC channel and other materials for the metallic source and drain. However, metal/semiconductor interfaces that are made of similar TMDC materials are anticipated to be better candidates because they provide better chemical bonding and thus smaller resistance. Furthermore, smaller resistance is expected to be achieved with a metal and a semiconductor that are joined in direct lateral contact. In this work, we use density functional theory to analyze the electronic structure properties of novel lateral TMDC metal/semiconductor heterojunctions. We discover promising metal/semiconductor heterojunctions, for example, VS2/CrS2, which is characterized by strong covalent bonds with limited metal-induced gap states, high charge density around the Fermi level, and no Schottky barrier. These properties are anticipated to be useful for practical implementation of these material heterojunctions in all two-dimensional transistors.