Radiative control of dark excitons at room temperature by nano-optical antenna-tip Purcell effect
Radiative control of dark excitons at room temperature by nano-optical antenna-tip Purcell effect
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DOI：
10.1038/s41565-017-0003-0
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发表时间：
2018-01-01
影响因子：
38.3
通讯作者：
Raschke, Markus B.
中科院分区：
文献类型：
--
作者：
Park, Kyoung-Duck;Jiang, Tao;Raschke, Markus B.
激子，库仑束缚的电子-空穴对，是半导体中的基本光激发，其可以通过辐射弛豫耦合到光。相比之下，暗激子（X-D）显示出反平行的自旋配置与一般禁止的辐射发射。由于它们的寿命长，这些暗激子是量子计算和光电子学的有吸引力的候选者。然而，XD状态的光学读出和控制由于其与光的解耦而仍然具有挑战性。在这里，我们提出了一种尖端增强的纳米光学方法，在室温下诱导，开关和可编程调制的XD发射。在金基底上使用单层过渡金属二硫属化物（TMD）WSe 2，我们证明了通过天线尖端与暗激子面外光学偶极矩的耦合实现的暗激子光致发光量子产率的类似6 × 10（5）倍增强，其中尖端样品纳米腔的大珀塞尔因子>= 2 × 10（3）。我们的方法提供了一种简便的方法来利用激子特性在低维半导体量子光电子学提供新的策略。
Excitons, Coulomb-bound electron-hole pairs, are elementary photo-excitations in semiconductors that can couple to light through radiative relaxation. In contrast, dark excitons (X-D) show anti-parallel spin configuration with generally forbidden radiative emission. Because of their long lifetimes, these dark excitons are appealing candidates for quantum computing and optoelectronics. However, optical read-out and control of XD states has remained challenging due to their decoupling from light. Here, we present a tip-enhanced nano-optical approach to induce, switch and programmably modulate the XD emission at room temperature. Using a monolayer transition metal dichalcogenide (TMD) WSe2 on a gold substrate, we demonstrate similar to 6 x 10(5)-fold enhancement in dark exciton photoluminescence quantum yield achieved through coupling of the antenna-tip to the dark exciton out-of-plane optical dipole moment, with a large Purcell factor of >= 2 x 10(3) of the tip-sample nano-cavity. Our approach provides a facile way to harness excitonic properties in low-dimensional semiconductors offering new strategies for quantum optoelectronics.