Photooxidation and quantum confinement effects in exfoliated black phosphorus
Photooxidation and quantum confinement effects in exfoliated black phosphorus
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DOI：
10.1038/nmat4299
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发表时间：
2015-08-01
期刊：
影响因子：
41.2
通讯作者：
Martel, Richard
中科院分区：
文献类型：
--
作者：
Favron, Alexandre;Gaufres, Etienne;Martel, Richard
黑磷薄层最近因其二维 (2D) 半导体特性（例如可调谐直接带隙和高载流子迁移率）而引起了人们的兴趣。这种磷原子的层状晶体可以使用类似于石墨烯的程序剥离成单层 2D 膦（也称为磷烯）。然而，探测这些特性受到了暴露于环境条件下最薄层快速降解的挑战。在这里，我们使用原位拉曼光谱和透射电子光谱研究了这种化学反应。结果强调了溶解在吸附水中的氧与厚度相关的光辅助氧化反应。氧化动力学与涉及电子转移和量子限制作为关键参数的唯象模型一致。在手套箱中进行的程序用于制备原始状态的单、双和多层二维磷烷，以进一步研究层厚度对拉曼模式的影响。在环境条件下进行的对照实验表明，超薄层的 A(g)(1)/A(g)(2) 强度比（氧化的特征）会降低。
Thin layers of black phosphorus have recently raised interest owing to their two-dimensional (2D) semiconducting properties, such as tunable direct bandgap and high carrier mobilities. This lamellar crystal of phosphorus atoms can be exfoliated down to monolayer 2D-phosphane (also called phosphorene) using procedures similar to those used for graphene. Probing the properties has, however, been challenged by a fast degradation of the thinnest layers on exposure to ambient conditions. Herein, we investigate this chemistry using in situ Raman and transmission electron spectroscopies. The results highlight a thickness-dependent photoassisted oxidation reaction with oxygen dissolved in adsorbed water. The oxidation kinetics is consistent with a phenomenological model involving electron transfer and quantum confinement as key parameters. A procedure carried out in a glove box is used to prepare mono-, bi- and multilayer 2D-phosphane in their pristine states for further studies on the effect of layer thickness on the Raman modes. Controlled experiments in ambient conditions are shown to lower the A(g)(1)/A(g)(2) intensity ratio for ultrathin layers, a signature of oxidation.