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<p>Point defects critically govern the properties of two-dimensional semiconductors, yet their atomic-scale characteristics in the emerging MoSi<sub>2</sub>N<sub>4</sub> family remain unexplored. Here we combine atomic-resolution scanning transmission electron microscopy and first-principles calculations to systematically investigate point defects in monolayer semiconducting WSi<sub>2</sub>N<sub>4</sub> and MoSi<sub>2</sub>N<sub>4</sub>. We identify ten distinct defect types, with Si-for-top-N antisites (Si<sub>N(t)</sub>), double-middle-N divacancies (V<sub>N(m)2</sub>), and double-top-N divacancies (V<sub>N(t)2</sub>) being the most abundant. These defects induce mobility modulation and bandgap reduction — in some cases leading to complete band closure and insulator-to-metal transitions — and, in certain configurations, give rise to spin-polarized bands with localized magnetic moments. Additionally, we observe low-dimensional assemblies formed via defect self-organization, including 2D Si<sub>N(t)</sub> networks and 1D Si2<sub>Mo</sub> chains. Our findings establish fundamental defect–property relationships and provide insights for defect-driven engineering of electronic and magnetic states in 2D WSi<sub>2</sub>N<sub>4</sub> and MoSi<sub>2</sub>N<sub>4</sub> semiconductors.</p>

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Point defects in monolayer WSi2N4 and MoSi2N4

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月23日

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  • Jinmeng Tong,
  • Yu Cao,
  • Yuan-Kun Wang,
  • Zhibo Liu,
  • Dayong Yang,
  • Chengjian He,
  • Chuan Xu,
  • Peitao Liu,
  • Shao-Chun Li,
  • Xing-Qiu Chen,
  • Wencai Ren

摘要

Point defects critically govern the properties of two-dimensional semiconductors, yet their atomic-scale characteristics in the emerging MoSi2N4 family remain unexplored. Here we combine atomic-resolution scanning transmission electron microscopy and first-principles calculations to systematically investigate point defects in monolayer semiconducting WSi2N4 and MoSi2N4. We identify ten distinct defect types, with Si-for-top-N antisites (SiN(t)), double-middle-N divacancies (VN(m)2), and double-top-N divacancies (VN(t)2) being the most abundant. These defects induce mobility modulation and bandgap reduction — in some cases leading to complete band closure and insulator-to-metal transitions — and, in certain configurations, give rise to spin-polarized bands with localized magnetic moments. Additionally, we observe low-dimensional assemblies formed via defect self-organization, including 2D SiN(t) networks and 1D Si2Mo chains. Our findings establish fundamental defect–property relationships and provide insights for defect-driven engineering of electronic and magnetic states in 2D WSi2N4 and MoSi2N4 semiconductors.