The two-dimensional (2D) semiconducting family of XSi₂N₄ (X = Mo and W), an emergent class of air-stable monolayers, has recently gained attention due to its distinctive structural, mechanical, transport, and optical properties. However, the electrical contact between XSi₂N₄ and metals remains a mystery. In this study, we inspect the electronic and transport properties, specifically the Schottky barrier height (SBH) and tunneling probability, of XSi₂N₄-based van der Waals contacts by means of first-principles calculations. Our findings reveal that the electrical contacts of XSi₂N₄ with metals can serve as the foundation for nanoelectronic devices with ultralow SBHs. We further analyzed the tunneling probability of different metal contacts with XSi₂N₄. We found that the H-phase XSi₂N₄/metal contact shows superior tunneling probability compared to that of H́-based metal contacts. Our results suggest that heterostructures at interfaces can potentially enable efficient tunneling barrier modulation in metal contacts, particularly in the case of MoSi₂N₄/borophene compared to MoSi₂N₄/graphene and WSi₂N₄/graphene in transport-efficient electronic devices. Among the studied heterostructures, tunneling efficiency is highest at the H and H́-MoSi₂N₄/borophene interfaces, with barrier heights of 2.1 and 1.52 eV, respectively, and barrier widths of 1.04 and 0.8 Å. Furthermore, the tunneling probability for these interfaces was identified to be 21.3 and 36.4%, indicating a good efficiency of carrier injection. Thus, our study highlights the potential of MoSi₂N₄/borophene contact in designing power-efficient Ohmic devices.

中文翻译：

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肖特基势垒高度的计算见解：石墨烯和硼烯与 H- 和 H́-XSi2N4 (X = Mo, W) 单层的界面

二维 (2D) 半导体族 XSi ₂ N ₄（X = Mo 和 W）是一类新兴的空气稳定单分子层，最近因其独特的结构、机械、传输和光学特性而受到关注。然而，XSi ₂ N ₄和金属之间的电接触仍然是个谜。在这项研究中，我们通过第一原理计算检查了基于 XSi ₂ N ₄的范德华接触的电子和输运特性，特别是肖特基势垒高度 (SBH) 和隧道概率。我们的研究结果表明，XSi ₂ N ₄与金属的电接触可以作为具有超低SBH的纳米电子器件的基础。我们进一步分析了不同金属与XSi ₂ N ₄接触的隧道概率。我们发现，与 H́ 基金属接触相比，H 相 XSi ₂ N ₄ /金属接触表现出更高的隧道概率。我们的结果表明，界面处的异质结构有可能在金属接触中实现有效的隧道势垒调制，特别是在传输高效电子器件中，与 MoSi 2 N 4 /石墨烯和 WSi 2 N 4 /石墨烯_相比，_MoSi 2 _N 4 /_硼烯的_情况。在所研究的异质结构中，隧道效率在H和H́-MoSi ₂ N ₄ /硼烯界面处最高，势垒高度分别为2.1和1.52 eV，势垒宽度分别为1.04和0.8 Å。此外，这些界面的隧道概率被确定为 21.3% 和 36.4%，表明载流子注入效率良好。因此，我们的研究强调了 MoSi ₂ N ₄ /硼烯接触在设计节能欧姆器件中的潜力。