State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Nanoscale. 2018 Feb 15;10(7):3540-3546. doi: 10.1039/c7nr08941d.
Two-dimensional semiconducting transition metal dichalcogenides have been employed as key components in various electronic devices. The thermal stability of these ultrathin materials must be carefully considered in device applications because the heating caused by current flow, light absorption, or other harsh environmental conditions is usually unavoidable. In this work, we found that the substrate plays a role in modifying the thermal stability of mono- and few-layer MoS. Triangular etching holes, which are considered to initiate from defect sites, form on MoS when the temperature exceeds a threshold. On AlO and SiO, monolayer MoS is found to be more stable in thermal annealing than few-layer MoS either in atmospheric-pressure air or under vacuum; while on mica, the absolute opposite behavior exists. However, this difference due to substrates appears to vanish when using defective, chemical-vapor-deposited MoS samples. The substrate modification of the thermal stability of MoS with various thicknesses is attributed to the competition between MoS-substrate interface interaction and MoS-MoS interlayer interaction. Our findings provide important design rules for MoS-based devices, and also potentially point to a route of controlled patterning of MoS with substrate engineering.
二维过渡金属二硫属化物已被用作各种电子设备的关键组件。由于电流流动、光吸收或其他恶劣环境条件引起的加热通常是不可避免的，因此在器件应用中必须仔细考虑这些超薄材料的热稳定性。在这项工作中，我们发现衬底在修饰单层和少层 MoS 的热稳定性方面起着作用。当温度超过阈值时，MoS 上会形成三角形刻蚀孔，这些孔被认为是从缺陷部位开始形成的。在 AlO 和 SiO 上，无论是在大气压空气中还是在真空中，单层 MoS 在热退火中的稳定性都比少层 MoS 高；而在云母上，则存在截然相反的行为。然而，当使用有缺陷的化学气相沉积 MoS 样品时，这种由于衬底引起的差异似乎消失了。衬底对各种厚度的 MoS 热稳定性的修饰归因于 MoS-衬底界面相互作用与 MoS-MoS 层间相互作用之间的竞争。我们的发现为基于 MoS 的器件提供了重要的设计规则，也可能为通过衬底工程对 MoS 进行受控图案化指明了一条途径。
