2D vibrational properties of epitaxial silicene on Ag(111)
2D vibrational properties of epitaxial silicene on Ag(111)
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DOI：
10.1088/2053-1583/4/1/015008
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发表时间：
2017-03-01
期刊：
影响因子：
5.5
通讯作者：
Vogt, Patrick
中科院分区：
文献类型：
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作者：
Solonenko, Dmytro;Gordan, Ovidiu D.;Vogt, Patrick
二维硅的同素异形体，硅烯，可以刺激硅基纳米技术的新的和原始的概念的发展。迄今为止，硅烯只能在Ag（111）等支撑衬底上外延生长。尽管这些外延硅烯层的结构和电子特性已经被深入研究，但对其振动特性知之甚少。在这里，我们提出了一个详细的研究外延硅烯在Ag（111）使用原位拉曼光谱，这是最广泛采用的实验技术，以表征二维材料，如石墨烯，过渡金属二硫属化物，和黑磷。外延硅烯的振动指纹，在所有以前的解释相反，其特征在于由三个不同的声子模式与A和E对称性。这些模式的能量和对称性都通过从头计算得到了证实。这些模式的温度依赖的光谱演化表明，独特的热性能的外延硅烯和显着的电子-声子耦合。这些结果明确地支持外延硅烯的纯二维特征，直到约300摄氏度，于是发生2D到3D的相变。外延硅烯的详细指纹将使我们能够在不同的环境中识别它或研究它的修饰。
The two-dimensional silicon allotrope, silicene, could spur the development of new and original concepts in Si-based nanotechnology. Up to now silicene can only be epitaxially synthesized on a supporting substrate such as Ag(111). Even though the structural and electronic properties of these epitaxial silicene layers have been intensively studied, very little is known about its vibrational characteristics. Here, we present a detailed study of epitaxial silicene on Ag(111) using in situ Raman spectroscopy, which is one of the most extensively employed experimental techniques to characterize 2D materials, such as graphene, transition metal dichalcogenides, and black phosphorous. The vibrational fingerprint of epitaxial silicene, in contrast to all previous interpretations, is characterized by three distinct phonon modes with A and E symmetries. Both, energies and symmetries of theses modes are confirmed by ab initio theory calculations. The temperature dependent spectral evolution of these modes demonstrates unique thermal properties of epitaxial silicene and a significant electron-phonon coupling. These results unambiguously support the purely two-dimensional character of epitaxial silicene up to about 300 degrees C, whereupon a 2D-to-3D phase transition takes place. The detailed fingerprint of epitaxial silicene will allow us to identify it in different environments or to study its modifications.