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arXiv 1609.04643physics.optics
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CdSe：CdS胶体量子点的太赫兹驱动发光和巨斯塔克效应

Terahertz-driven Luminescence and Colossal Stark Effect in CdSe:CdS Colloidal Quantum Dots

Brandt C. Pein, Wendi Chang, Harold Y. Hwang, Jennifer Scherer, Igor Coropceanu, Xiaoguang Zhao, Xin Zhang, Vladimir Bulović, Moungi Bawendi, Keith A. Nelson

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8 pages, 4 figures, supplementary information
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摘要：

胶体半导体量子点（QD）的独特光学性质，产生于这些结构内的电荷的量子力学约束，为研究高电场如何影响纳米结构固体的电子结构提供了一个通用的测试平台。早期的准直流电场对量子点性质调制的研究一直受到高外加电场下静电击穿过程的限制，这限制了量子点性质的调制范围。相比之下，在目前的工作中，我们驱动的CdSe：CdS核：壳量子点薄膜与高场太赫兹频率的电磁脉冲，其持续时间只有几皮秒。令人惊讶的是，响应于太赫兹激发，我们观察到量子点发光，即使在没有外部电荷源。我们的实验表明，量子点发光是与一个非常高的和快速的调制的量子点带隙，这是改变超过0.5 eV（对应于25%的未扰动的带隙能量）的皮秒时间范围内的太赫兹场分布。我们表明，这些巨大的能量转移可以一致地解释量子限制斯塔克效应。我们的工作展示了一种在材料组或几何形状没有构型变化的情况下对材料特性进行极端调制的途径。此外，我们期望该平台可以适用于一种新颖的紧凑型THz检测方案，其中THz场（具有meV级光子能量）到可见光/近红外波段（具有eV级光子能量）的转换可以在室温下实现，具有高带宽和灵敏度。

英文摘要：

Unique optical properties of colloidal semiconductor quantum dots (QDs), arising from quantum mechanical confinement of charge within these structures, present a versatile testbed for the study of how high electric fields affect the electronic structure of nanostructured solids. Earlier studies of quasi-DC electric field modulation of QD properties have been limited by the electrostatic breakdown processes under the high externally applied electric fields, which have restricted the range of modulation of QD properties. In contrast, in the present work we drive CdSe:CdS core:shell QD films with high-field THz-frequency electromagnetic pulses whose duration is only a few picoseconds. Surprisingly, in response to the THz excitation we observe QD luminescence even in the absence of an external charge source. Our experiments show that QD luminescence is associated with a remarkably high and rapid modulation of the QD band-gap, which is changing by more than 0.5 eV (corresponding to 25% of the unperturbed bandgap energy) within the picosecond timeframe of THz field profile. We show that these colossal energy shifts can be consistently explained by the quantum confined Stark effect. Our work demonstrates a route to extreme modulation of material properties without configurational changes in material sets or geometries. Additionally, we expect that this platform can be adapted to a novel compact THz detection scheme where conversion of THz fields (with meV-scale photon energies) to the visible/near-IR band (with eV-scale photon energies) can be achieved at room temperature with high bandwidth and sensitivity.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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