Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States.
ACS Nano. 2014 Dec 23;8(12):12682-9. doi: 10.1021/nn5056942. Epub 2014 Dec 10.
We report on the fabrication of monolayer MoS2-coated gold nanoantennas combining chemical vapor deposition, e-beam lithography surface patterning, and a soft lift-off/transfer technique. The optical properties of these hybrid plasmonic-excitonic nanostructures are investigated using spatially resolved photoluminescence spectroscopy. Off- and in-resonance plasmonic pumping of the MoS2 excitonic luminescence showed distinct behaviors. For plasmonically mediated pumping, we found a significant enhancement (∼65%) of the photoluminescence intensity, clear evidence that the optical properties of the MoS2 monolayer are strongly influenced by the nanoantenna surface plasmons. In addition, a systematic photoluminescence broadening and red-shift in nanoantenna locations is observed which is interpreted in terms of plasmonic enhanced optical absorption and subsequent heating of the MoS2 monolayers. Using a temperature calibration procedure based on photoluminescence spectral characteristics, we were able to estimate the local temperature changes. We found that the plasmonically induced MoS2 temperature increase is nearly four times larger than in the MoS2 reference temperatures. This study shines light on the plasmonic-excitonic interaction in these hybrid metal/semiconductor nanostructures and provides a unique approach for the engineering of optoelectronic devices based on the light-to-current conversion.
我们报告了一种通过化学气相沉积、电子束光刻表面图案化和软剥离/转移技术制备单层 MoS2 覆盖的金纳米天线的方法。使用空间分辨光致发光光谱研究了这些混合等离子体-激子纳米结构的光学性质。MoS2 激子发光的离谐和谐等离子体泵浦表现出明显不同的行为。对于等离子体介导的泵浦，我们发现光致发光强度显著增强（约 65%），这清楚地表明 MoS2 单层的光学性质受到纳米天线表面等离激元的强烈影响。此外，在纳米天线位置观察到系统的光致发光展宽和红移，这可以解释为等离子体增强的光吸收以及随后 MoS2 单层的加热。使用基于光致发光光谱特性的温度校准程序，我们能够估计局部温度变化。我们发现，等离子体诱导的 MoS2 温度升高几乎是 MoS2 参考温度的四倍。这项研究揭示了这些混合金属/半导体纳米结构中的等离子体-激子相互作用，并为基于光电流转换的光电设备工程提供了一种独特的方法。
