Sabbaghi Soroush, Bazargan Vahid, Hosseinian Ehsan
Department of Mechanical Engineering, University of Tehran, Tehran, Iran.
Nanoscale. 2023 Aug 3;15(30):12634-12647. doi: 10.1039/d3nr01839c.
Molybdenum diselenide (MoSe) is attracting great attention as a transition metal dichalcogenide (TMDC) due to its unique applications in micro-electronics and beyond. In this study, the role of defects in the thermal transport properties of single-layer MoSe is investigated using non-equilibrium molecular dynamics (NEMD) simulations. Specifically, this work quantifies how different microstructural defects such as vacancies and grain boundaries (GBs) and their concentration () alter the thermal conductivity (TC) of single crystal and nanocrystalline MoSe. These results show a significant drop in thermal conductivity as the concentration of defects increases. Specifically, point defects lower the TC of MoSe in the form of where is 0.5, 0.48 and 0.36 for V, V and V vacancies, respectively. This study also examines the impact of grain boundaries on the thermal conductivity of nanocrystalline MoSe. These results suggest that GB migration and stress-assisted twinning along with localized phase transformation (2H to 1T) are the primary factors affecting the thermal conductivity of nanocrystalline MoSe. Based on MD simulations, TC of polycrystalline MoSe increases with the average grain size () in the form of . For example, the TC of nanocrystalline MoSe with = 11 nm is around 40% lower than the TC of the pristine monocrystalline sample with the same dimensions. Finally, the influence of sample size and temperature is studied to determine the sensitivity of quantitative thermal properties to the length scale and phonon scattering, respectively. The results of this work could provide valuable insights into the role of defects in engineering the thermal properties of next generation semiconductor-based devices.
二硒化钼（MoSe₂）作为一种过渡金属二硫属化物（TMDC），因其在微电子及其他领域的独特应用而备受关注。在本研究中，使用非平衡分子动力学（NEMD）模拟研究了缺陷在单层MoSe₂热输运性质中的作用。具体而言，这项工作量化了不同的微观结构缺陷，如空位和晶界（GBs）及其浓度（）如何改变单晶和纳米晶MoSe₂的热导率（TC）。这些结果表明，随着缺陷浓度的增加，热导率显著下降。具体来说，点缺陷以的形式降低了MoSe₂的热导率，其中V、V和V空位的分别为0.5、0.48和0.36。本研究还考察了晶界对纳米晶MoSe₂热导率的影响。这些结果表明，晶界迁移、应力辅助孪晶以及局部相变（2H到1T）是影响纳米晶MoSe₂热导率的主要因素。基于分子动力学模拟，多晶MoSe₂的热导率随平均晶粒尺寸（）以的形式增加。例如，平均晶粒尺寸 = 11 nm的纳米晶MoSe₂的热导率比相同尺寸的原始单晶样品的热导率低约40%。最后，研究了样品尺寸和温度的影响，以分别确定定量热性质对长度尺度和声子散射的敏感性。这项工作的结果可为缺陷在设计下一代半导体基器件热性质中的作用提供有价值的见解。
