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Giant Enhancement of Defect-Bound Exciton Luminescence and Suppression of Band-Edge Luminescence in Monolayer WSe2–Ag Plasmonic Hybrid Structures
Nano Letters ( IF 9.6 ) Pub Date : 2017-05-31 00:00:00 , DOI: 10.1021/acs.nanolett.7b01364 Alex D. Johnson 1 , Fei Cheng 1 , Yutsung Tsai 1 , Chih-Kang Shih 1
Nano Letters ( IF 9.6 ) Pub Date : 2017-05-31 00:00:00 , DOI: 10.1021/acs.nanolett.7b01364 Alex D. Johnson 1 , Fei Cheng 1 , Yutsung Tsai 1 , Chih-Kang Shih 1
Affiliation
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We have investigated how the photoluminescence (PL) of WSe2 is modified when coupled to Ag plasmonic structures at low temperature. Chemical vapor deposition (CVD) grown monolayer WSe2 flakes were transferred onto a Ag film and a Ag nanotriangle array that had a 1.5 nm Al2O3 capping layer. Using low-temperature (7.5 K) micro-PL mapping, we simultaneously observed enhancement of the defect-bound exciton emission and quenching of the band edge exciton emission when the WSe2 was on a plasmonic structure. The enhancement of the defect-bound exciton emission was significant with enhancement factors of up to ∼200 for WSe2 on the nanotriangle array when compared to WSe2 on a 1.5 nm Al2O3 capped Si substrate with a 300 nm SiO2 layer. The giant enhancement of the luminescence from the defect-bound excitons is understood in terms of the Purcell effect and increased light absorption. In contrast, the surprising result of luminescence quenching of the bright exciton state on the same plasmonic nanostructure is due to a rather unique electronic structure of WSe2: the existence of a dark state below the bright exciton state.
中文翻译：
单层WSe 2 -Ag等离子体混合结构中缺陷结合激子发光的巨大增强和带边发光的抑制。
我们已经研究了在低温下耦合到Ag等离子体结构时WSe 2的光致发光（PL）是如何被修饰的。将化学气相沉积（CVD）生长的单层WSe 2薄片转移到具有1.5 nm Al 2 O 3覆盖层的Ag膜和Ag纳米三角形阵列上。使用低温（7.5 K）micro-PL映射，我们同时观察到当WSe 2在等离激元结构上时，缺陷结合激子发射的增强和带边缘激子发射的猝灭。与WSe 2相比，纳米三角形阵列上WSe 2的缺陷结合激子发射增强显着，增强因子高达〜200。在具有300 nm SiO 2层的1.5 nm Al 2 O 3覆盖的Si衬底上。根据赛尔效应和增加的光吸收，可以理解与缺陷结合的激子发光的极大增强。相反，在相同的等离子体纳米结构上亮激子态的发光猝灭的令人惊讶的结果是由于WSe 2的相当独特的电子结构：在亮激子态之下存在暗态。
更新日期：2017-06-28
中文翻译：
单层WSe 2 -Ag等离子体混合结构中缺陷结合激子发光的巨大增强和带边发光的抑制。
我们已经研究了在低温下耦合到Ag等离子体结构时WSe 2的光致发光（PL）是如何被修饰的。将化学气相沉积（CVD）生长的单层WSe 2薄片转移到具有1.5 nm Al 2 O 3覆盖层的Ag膜和Ag纳米三角形阵列上。使用低温（7.5 K）micro-PL映射，我们同时观察到当WSe 2在等离激元结构上时，缺陷结合激子发射的增强和带边缘激子发射的猝灭。与WSe 2相比，纳米三角形阵列上WSe 2的缺陷结合激子发射增强显着，增强因子高达〜200。在具有300 nm SiO 2层的1.5 nm Al 2 O 3覆盖的Si衬底上。根据赛尔效应和增加的光吸收，可以理解与缺陷结合的激子发光的极大增强。相反，在相同的等离子体纳米结构上亮激子态的发光猝灭的令人惊讶的结果是由于WSe 2的相当独特的电子结构：在亮激子态之下存在暗态。
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