Schottky barrier heights and mechanism of charge transfer at metal-Bi2OS2 interfaces

Strong Fermi-level pinning (FLP) always occurs at the two-dimensional (2D) semiconductor-metal interface due to complex interfacial charge transfer. By using monolayer (ML) Bi2OS2, an emerging 2D semiconductor with highest electron mobility, Schottky barrier heights (SBHs) and origin of transfer Bi2OS2-metal interfaces are systematically studied based on density functional theory calculations. In 3D metal-Bi2OS2 interfaces, formation chemical bonding effect Pauli exchange repulsion found be responsible for strong transfer, resulting in FLP, direction induced by two factors is opposite. Besides, extra expected equilibrate Fermi level when work functions (WFs) metal electrodes out range affinity energy ionization semiconductors. For metal-ML Bi2OS2 surprisingly, FLP entirely suppressed, thereby, contacts obey conventional Schottky-Mott model. Such intriguing behavior arises from chosen this can effectively shield repulsion. Consequently, wide-range linear-tunable SBHs obtained conversion n-type Ohmic contact p-type achieved different WFs. This study not only provides a theoretical foundation selecting favorable devices ML but also helps enhance understanding mechanism interaction between metals