Tailoring excitonic states of van der Waals bilayers through stacking configuration, band alignment, and valley spin
Tailoring excitonic states of van der Waals bilayers through stacking configuration, band alignment, and valley spin
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DOI：
10.1126/sciadv.aax7407
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发表时间：
2019-12-01
期刊：
影响因子：
13.6
通讯作者：
Shih, Chih-Kang
中科院分区：
文献类型：
--
作者：
Hsu, Wei-Ting;Lin, Bo-Han;Shih, Chih-Kang
单层半导体中的激子有一个大的光学跃迁偶极子，用于与光的强耦合。异质双层中的层间激子具有一个大的电偶极子，它能够与电场强耦合，并以小的光学偶极为代价实现激子-激子相互作用。我们展示了在异质双分子膜和同双分子膜中创建一类新的激子的能力，它结合了单分子层和层间激子的优点，即具有大的光学和电偶极子。这些激子由限制在单个层中的电子和在两层中延伸的空穴组成，其中依赖于载流子物种的层杂化可以通过旋转、平移、带偏移和谷自旋自由度来控制。我们观察到了不同种类的层杂谷激子，它们可以用来实现强相互作用的极化子气体和层间双向载流子转移的光学量子控制。
Excitons in monolayer semiconductors have a large optical transition dipole for strong coupling with light. Interlayer excitons in heterobilayers feature a large electric dipole that enables strong coupling with an electric field and exciton-exciton interaction at the cost of a small optical dipole. We demonstrate the ability to create a new class of excitons in hetero- and homobilayers that combines advantages of monolayer and interlayer excitons, i.e., featuring both large optical and electric dipoles. These excitons consist of an electron confined in an individual layer, and a hole extended in both layers, where the carrier-species-dependent layer hybridization can be controlled through rotational, translational, band offset, and valley-spin degrees of freedom. We observe different species of layer-hybridized valley excitons, which can be used for realizing strongly interacting polaritonic gases and optical quantum controls of bidirectional interlayer carrier transfer.