摘要
Recently, it has been reported that physisorbed adsorbates can be trapped between the bottom surface of twodimensional(2D) materials and supported substrate to form2 D confined films. However, the influence of such 2D confined adsorbates on the properties of 2D materials is rarely explored. Herein, we combined atomic force microscopy(AFM), Kelvin probe force microscopy(KPFM) and Raman spectroscopy especially the ultralow frequency(ULF) Raman spectroscopy to explore the influence of 2D confined organic adlayer thickness on the ULF breathing modes of few-layer MoS2 and WSe2nanosheets. As the thickness of organic adlayers increased, red shift, coexistence of blue and red shifts as well as blue shift of ULF breathing mode was observed. KPFM measurement confirmed the enhanced n-doping and p-doping behaviors of organic adlayers as their thickness increased,respectively. Our results will provide new insights into the interaction between 2D confined adsorbates and bottom surface of 2D nanosheets, which could be useful for modulating properties of 2D materials.
在二维材料下表面与衬底之间的受限空间中,物理吸附物如水分子和有机分子等可形成二维吸附层.然而,这类吸附层如何影响其上层二维材料的性能尚未被探究.本文中,我们结合原子力显微镜、开尔文力显微镜以及超低波拉曼光谱仪来探究有机分子吸附层对其上的少层二硫化钼及二硒化钨纳米薄片性质的影响.随吸附层厚度增加,纳米薄片的超低波呼吸模式拉曼峰发生红移、红移和蓝移共存以及仅有蓝移的现象.此外,纳米薄片的掺杂程度也逐渐增强.理解有机分子吸附层与二维材料下表面之间的相互作用,有望对二维材料性质的调节提供帮助.
基金
supported by the National Natural Science Foundation of China (21571101 and 51322202)
the Natural Science Foundation of Jiangsu Province in China (BK20161543 and BK20130927)
the Joint Research Fund for Overseas Chinese, Hong Kong and Macao Scholars (51528201)
Natural Science Foundation of Jiangsu Higher Education Institutions of China (15KJB430016)
