Fortin-Deschênes Matthieu, Levesque Pierre L, Martel Richard, Moutanabbir Oussama
Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada.
Département de Chimie, Université de Montréal , 2900 Boulevard Edouard Montpetit, Montréal, Québec H3T 1J4, Canada.
J Phys Chem Lett. 2016 May 5;7(9):1667-74. doi: 10.1021/acs.jpclett.6b00584. Epub 2016 Apr 20.
We report on real time observations of the sublimation of exfoliated black phosphorus layers throughout annealing using in situ low energy electron microscopy. We found that sublimation manifests itself above 375 ± 20 °C through the nucleation and expansion of asymmetric, faceted holes with the long axis aligned along the [100] direction and sharp tips defined by edges consisting of alternating (10) and (11) steps. This thermally activated process repeats itself via successive sublimation of individual layers. Calculations and simulations using density functional theory and kinetic Monte Carlo allowed to determine the involved atomic pathways. Sublimation is found to occur via detachments of phosphorus dimers rather than single atoms. This behavior and the role of defects is described using an analytical model that captures all essential features. This work establishes an atomistic-level understanding of the thermal stability of exfoliated black phosphorus and defines the temperature window available for material and device processing.
我们报告了使用原位低能电子显微镜对剥离的黑磷层在整个退火过程中的升华进行的实时观察。我们发现，升华在375±20°C以上通过不对称的多面孔的成核和扩展表现出来，这些孔的长轴沿[100]方向排列，尖锐的尖端由交替的(10)和(11)台阶组成的边缘定义。这个热激活过程通过单个层的连续升华重复进行。使用密度泛函理论和动力学蒙特卡罗进行的计算和模拟确定了所涉及的原子路径。发现升华是通过磷二聚体的脱离而不是单个原子发生的。使用捕获所有基本特征的分析模型描述了这种行为和缺陷的作用。这项工作建立了对剥离黑磷热稳定性的原子水平理解，并定义了可用于材料和器件加工的温度窗口。
