Metal contacts to two-dimensional (2D) semiconductors are often plagued by the strong Fermi level pinning (FLP) effect which reduces the tunability of the Schottky barrier height (SBH) and degrades the performance of 2D semiconductor devices. Here, we show that MoSi₂N₄ and WSi₂N₄ monolayers—an emerging 2D semiconductor family with exceptional physical properties—exhibit strongly suppressed FLP and wide-range tunable SBH. An exceptionally large SBH slope parameter of S ≈ 0.7 is obtained which outperforms the vast majority of other 2D semiconductors. Such intriguing behavior arises from the septuple-layered morphology of MoSi₂N₄ and WSi₂N₄ monolayers in which the semiconducting electronic states are protected by the outlying Si–N sublayer. We identify Ti, Sc, and Ni as highly efficient Ohmic contacts to MoSi₂N₄ and WSi₂N₄ with zero interface tunneling barrier. Our findings reveal the potential of MoSi₂N₄ and WSi₂N₄ as a practical platform for designing high-performance and energy-efficient 2D semiconductor electronic devices.

二维 (2D) 半导体的金属接触经常受到强费米能级钉扎 (FLP) 效应的困扰，该效应会降低肖特基势垒高度 (SBH) 的可调性并降低二维半导体器件的性能。在这里，我们展示了 MoSi ₂ N ₄和 WSi ₂ N ₄单层——一种具有特殊物理特性的新兴二维半导体系列——表现出强烈抑制的 FLP 和宽范围可调 SBH。的一个非常大的SBH斜率参数小号 获得0.7≈其优于绝大多数其它2D的半导体。这种有趣的行为源于 MoSi ₂ N ₄和 WSi ₂的七层形貌N ₄单层，其中半导体电子态受到外围 Si-N 子层的保护。我们将 Ti、Sc 和 Ni 确定为具有零界面隧道势垒的MoSi ₂ N ₄和 WSi ₂ N _{4 的}高效欧姆接触。我们的研究结果揭示了 MoSi ₂ N ₄和 WSi ₂ N ₄作为设计高性能和节能二维半导体电子器件的实用平台的潜力。