On the Working Mechanisms of Molecules‐Based Van der Waals Dielectrics

Abstract Sb₂O₃ molecules offer unprecedented opportunities for the integration of a van der Waals (vdW) dielectric and a 2D vdW semiconductor. However, the working mechanisms underlying molecules‐based vdW dielectrics remain unclear. Here, the working mechanisms of Sb₂O₃ and two Sb₂O₃‐like molecules (As₂O₃ and Bi₂O₃) as dielectrics are systematically investigated by combining first‐principles calculations and gate leakage current theories. It is revealed that molecules‐based vdW dielectrics have a considerable advantage over conventional dielectric materials: defects hardly affect their insulating properties. This shows that it is unnecessary to synthesize high‐quality crystals in practical applications, which has been a long‐standing challenge for conventional dielectric materials. Further analysis reveals that a large thermionic‐emission current renders Sb₂O₃ difficult to simultaneously satisfy the requirements of dielectric layers in p‐MOS and n‐MOS, which hinders its application for complementary metal‐oxide‐semiconductor (CMOS) devices. Remarkably, it is found that As₂O₃ can serve as a dielectric for both p‐MOS and n‐MOS. This work not only lays a theoretical foundation for the application of molecules‐based vdW dielectrics, but also offers an unprecedentedly competitive dielectric (i.e., As₂O₃) for 2D vdW semiconductors‐based CMOS devices, thus having profound implications for future semiconductor industry.