Tightly Bound Excitons in Monolayer WSe2
Tightly Bound Excitons in Monolayer WSe2
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DOI：
10.1103/physrevlett.113.026803
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发表时间：
2014-07-10
影响因子：
8.6
通讯作者：
Shan, Jie
中科院分区：
文献类型：
--
作者：
He, Keliang;Kumar, Nardeep;Shan, Jie
利用线性吸收光谱和双光子光致发光光谱研究了二硒化钨（WSe 2）单分子膜中激子的束缚能和激发态。激子结合能被确定为0.37 eV，这是大约一个数量级大于在III-V族半导体量子威尔斯和呈现激子激发态可观察到，即使在室温下。实验确定的单光子和双光子活性态的激子激发光谱不同于简单的二维（2D）类氢模型。这一结果揭示了显着减少和非局部介电屏蔽的库仑相互作用在二维半导体。观察到的大激子结合能也将对基于2D原子晶体的下一代光子学和光电子学应用产生重大影响。
Exciton binding energy and excited states in monolayers of tungsten diselenide (WSe2) are investigated using the combined linear absorption and two-photon photoluminescence excitation spectroscopy. The exciton binding energy is determined to be 0.37 eV, which is about an order of magnitude larger than that in III-V semiconductor quantum wells and renders the exciton excited states observable even at room temperature. The exciton excitation spectrum with both experimentally determined one-and two-photon active states is distinct from the simple two-dimensional (2D) hydrogenic model. This result reveals significantly reduced and nonlocal dielectric screening of Coulomb interactions in 2D semiconductors. The observed large exciton binding energy will also have a significant impact on next-generation photonics and optoelectronics applications based on 2D atomic crystals.