Segregation-Enhanced Epitaxy of Borophene on Ir(111) by Thermal Decomposition of Borazine
Segregation-Enhanced Epitaxy of Borophene on Ir(111) by Thermal Decomposition of Borazine
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DOI：
10.1021/acsnano.1c00819
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发表时间：
2021-03-24
期刊：
影响因子：
17.1
通讯作者：
Horn-von Hoegen, Michael
中科院分区：
文献类型：
--
作者：
Omambac, Karim M.;Petrovic, Marin;Horn-von Hoegen, Michael
与其他二维材料一样，硼基硼罗芬具有有趣的结构和电子特性。虽然硼烯通常是通过分子束外延制备的，但我们在这里报道了一种通过分离增强外延合成大单相硼烯结构域的替代方法。x射线光电子能谱显示，将硼嗪在1100摄氏度下加到Ir（111）上，可以得到富硼的表面，而没有氮的痕迹。在高温下，硼嗪热分解，氮解吸，硼扩散到底物中。利用飞行时间二次离子质谱法，我们发现在冷却过程中，地下硼分离回表面，在那里它形成硼苯。在这种情况下，电子衍射显示（6 × 2）重构的硼罗芬chi(6)-多晶型，扫描隧道光谱显示狄拉克类行为。在低能电子显微镜下对硼苯形成动力学的研究表明，在硼苯形成过程中，表面台阶聚集，导致具有特殊结构秩序的细长和延伸的硼苯结构域。
Like other 2D materials, the boron-based borophene exhibits interesting structural and electronic properties. While borophene is typically prepared by molecular beam epitaxy, we report here on an alternative way of synthesizing large single-phase borophene domains by segregation-enhanced epitaxy. X-ray photoelectron spectroscopy shows that borazine dosing at 1100 degrees C onto Ir(111) yields a boron-rich surface without traces of nitrogen. At high temperatures, the borazine thermally decomposes, nitrogen desorbs, and boron diffuses into the substrate. Using time-of-flight secondary ion mass spectrometry, we show that during cooldown the subsurface boron segregates back to the surface where it forms borophene. In this case, electron diffraction reveals a (6 x 2) reconstructed borophene chi(6)-polymorph, and scanning tunneling spectroscopy suggests a Dirac-like behavior. Studying the kinetics of borophene formation in low energy electron microscopy shows that surface steps are bunched during the borophene formation, resulting in elongated and extended borophene domains with exceptional structural order.