Song Jungeun, Kwon Soyeong, Kim Bora, Kim Eunah, Murthy Lakshmi N S, Lee Taejin, Hong Inhae, Lee Byoung Hoon, Lee Sang Wook, Choi Soo Ho, Kim Ki Kang, Cho Chang-Hee, Hsu Julia W P, Kim Dong-Wook
Department of Physics, Ewha Womans University, Seoul 03760, Korea.
Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea.
ACS Appl Mater Interfaces. 2020 Oct 28;12(43):48991-48997. doi: 10.1021/acsami.0c14563. Epub 2020 Oct 13.
We prepared MoS monolayers on Au nanodot (ND) and nanohole (NH) arrays. Both these sample arrays exhibited enhanced photoluminescence intensity compared with that of a bare SiO/Si substrate. The reflectance spectra of MoS/ND and MoS/NH had clear features originating from excitation of localized surface plasmon and propagating surface plasmon polaritons. Notably, the surface photovoltages (SPV) of these hybrid plasmonic nanostructures had opposite polarities, indicating negative and positive charging at MoS/ND and MoS/NH, respectively. Surface potential maps, obtained by Kelvin probe force microscopy, suggested that the potential gradient led to a distinct spatial distribution of photo-generated charges in these two samples under illumination. Furthermore, the local density of photo-generated excitons, as predicted from optical simulations, explained the SPV spectra of MoS/ND and MoS/NH. We show that the geometric configuration of the plasmonic nanostructures modified the polarity of photo-generated excess charges in MoS. These findings point to a useful means of optimizing optoelectronic characteristics and improving the performance of MoS-based plasmonic devices.
我们在金纳米点（ND）和纳米孔（NH）阵列上制备了单层二硫化钼（MoS）。与裸露的SiO/Si衬底相比，这两种样品阵列均表现出增强的光致发光强度。MoS/ND和MoS/NH的反射光谱具有源自局域表面等离子体激元和传播表面等离子体激元极化激元激发的清晰特征。值得注意的是，这些混合等离子体纳米结构的表面光电压（SPV）具有相反的极性，分别表明MoS/ND和MoS/NH处的负电荷和正电荷。通过开尔文探针力显微镜获得的表面电势图表明，电势梯度导致这两个样品在光照下光生电荷的明显空间分布。此外，光学模拟预测的光生激子的局部密度解释了MoS/ND和MoS/NH的SPV光谱。我们表明，等离子体纳米结构的几何构型改变了MoS中光生多余电荷的极性。这些发现指出了一种优化光电子特性和提高基于MoS的等离子体器件性能的有用方法。
