Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures
Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures
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DOI：
10.1126/science.abm8511
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发表时间：
2022-04-22
期刊：
影响因子：
56.9
通讯作者：
Heinz, Tony F.
中科院分区：
文献类型：
--
作者：
Barre, Elyse;Karni, Ouri;Heinz, Tony F.
层间激子，电子空穴对绑定在两个单层货车德瓦尔斯半导体，提供了有前途的电调谐性和局域化。由于这种激子显示出弱的电子-空穴重叠，大多数研究仅通过光致发光检查了最低能量的激子。我们直接测量了层间激子的介电响应，我们使用它们的静态电偶极矩来访问。因此，我们确定了0.40纳秒的最低直接间隙层间激子在二硒化钨/二硒化钼异质结构的固有辐射寿命。我们发现，电场和扭转角的差异诱导的激子跃迁强度和能量的趋势，这可能与波函数重叠，莫尔约束，和原子重建。通过与光致发光谱的比较，本研究确定了动量间接发射机制。吸收的表征是依赖于光-物质相互作用的应用的关键。
Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. Because such excitons display weak electron-hole overlap, most studies have examined only the lowest-energy excitons through photoluminescence. We directly measured the dielectric response of interlayer excitons, which we accessed using their static electric dipole moment. We thereby determined an intrinsic radiative lifetime of 0.40 nanoseconds for the lowest direct-gap interlayer exciton in a tungsten diselenide/molybdenum diselenide heterostructure. We found that differences in electric field and twist angle induced trends in exciton transition strengths and energies, which could be related to wave function overlap, moire confinement, and atomic reconstruction. Through comparison with photoluminescence spectra, this study identifies a momentum-indirect emission mechanism. Characterization of the absorption is key for applications relying on light-matter interactions.