SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University , Suwon 440-746, Korea.
Department of Energy Systems Engineering, DGIST (Daegu Gyeongbuk Institute of Science & Technology) , Daegu 42988, Korea.
ACS Nano. 2018 Jan 23;12(1):338-346. doi: 10.1021/acsnano.7b06417. Epub 2018 Jan 11.
The epitaxial synthesis of molybdenum carbide (MoC, a 2D MXene material) via chemical conversion of molybdenum disulfide (MoS) with thermal annealing under CH and H is reported. The experimental results show that adjusting the thermal annealing period provides a fully converted metallic MoC from MoS and an atomically sharp metallic/semiconducting hybrid structure via partial conversion of the semiconducting 2D material. MoC/MoS hybrid junctions display a low contact resistance (1.2 kΩ·μm) and low Schottky barrier height (26 meV), indicating the material's potential utility as a critical hybrid structural building block in future device applications. Density functional theory calculations are used to model the mechanisms by which MoC grows and forms a MoC/MoS hybrid structure. The results show that MoC conversion is initiated at the MoS edge and undergoes sequential hydrodesulfurization and carbide conversion steps, and an atomically sharp interface with MoS forms through epitaxial growth of MoC. This work provides the area-controllable synthesis of a manufacturable MXene from a transition metal dichalcogenide material and the formation of a metal/semiconductor junction structure. The present results will be of critical importance for future 2D heterojunction structures and functional device applications.
通过在 CH 和 H 下进行热退火，将二硫化钼 (MoS) 进行化学转化，报告了碳化钼 (MoC，二维 MXene 材料) 的外延合成。实验结果表明，通过调整热退火周期，从 MoS 完全转化为金属 MoC，并通过对半导体二维材料的部分转化，形成原子级锋利的金属/半导体混合结构。MoC/MoS 混合结显示出低接触电阻 (1.2 kΩ·μm) 和低肖特基势垒高度 (26 meV)，表明该材料作为未来器件应用中关键的混合结构构建块具有潜在的应用价值。密度泛函理论计算用于模拟 MoC 生长和形成 MoC/MoS 混合结构的机制。结果表明，MoC 转化在 MoS 边缘开始，并经历顺序加氢脱硫和碳化转化步骤，通过 MoC 的外延生长形成具有 MoS 的原子级锋利界面。这项工作提供了从过渡金属二硫属化物材料可控合成可制造 MXene 的方法，并形成了金属/半导体结结构。目前的结果对于未来的二维异质结结构和功能器件应用至关重要。
