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Electrically Tunable Localized versus Delocalized Intralayer Moiré Excitons and Trions in a Twisted MoS2 Bilayer
ACS Nano ( IF 15.8 ) Pub Date : 2022-06-09 , DOI: 10.1021/acsnano.2c00145 Medha Dandu 1 , Garima Gupta 1 , Pushkar Dasika 1 , Kenji Watanabe 2 , Takashi Taniguchi 3 , Kausik Majumdar 1
ACS Nano ( IF 15.8 ) Pub Date : 2022-06-09 , DOI: 10.1021/acsnano.2c00145 Medha Dandu 1 , Garima Gupta 1 , Pushkar Dasika 1 , Kenji Watanabe 2 , Takashi Taniguchi 3 , Kausik Majumdar 1
Affiliation
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Moiré superlattice (mSL)-induced sub-bands in twisted van der Waals homo- and heterostructures govern their optical and electrical properties, rendering additional degrees of freedom such as twist angle. Here, we demonstrate the moiré superlattice effects on the intralayer excitons and trions in a twisted bilayer of MoS2 of H-type stacking at marginal twist angles. We identify the emissions from localized and delocalized sub-bands of intralayer moiré excitons and show their electrical modulation by the corresponding trion formation. The electrical control of the oscillator strength of the moiré excitons also results in the strong tunability of resonant Raman scattering. We find that the gate-induced doping significantly modulates the electronic moiré potential; however, leaves the excitonic moiré confinement unaltered. This effect, coupled with variable moiré trap filling by tuning the optical excitation density, allows us to delineate the different phases of localized and delocalized moiré trions. We demonstrate that the moiré excitons exhibit strong valley coherence that changes in a striking nonmonotonic W-shape with gating due to motional narrowing. These observations from the simultaneous electrostatic control of quasiparticle-dependent moiré potential will lead to exciting effects of tunable many-body phenomena in moiré superlattices.
中文翻译：
扭曲的 MoS2 双层中的电可调局部与离域层内莫尔激子和三角子
扭曲范德瓦尔斯同质结构和异质结构中莫尔超晶格 (mSL) 诱导的子带控制着它们的光学和电学特性，从而提供额外的自由度，例如扭曲角。在这里，我们展示了莫尔超晶格对 MoS 2扭曲双层中层内激子和三重子的影响边缘扭转角的 H 型堆叠。我们确定了层内莫尔激子的局域化和离域子带的发射，并通过相应的 trion 形成显示它们的电调制。莫尔激子的振荡器强度的电气控制也导致共振拉曼散射的强可调谐性。我们发现栅极诱导掺杂显着调节了电子莫尔电位；然而，激子云纹限制没有改变。这种效应，加上通过调整光激发密度来填充可变波纹陷阱，使我们能够描绘出局部和离域波纹三重子的不同阶段。我们证明了莫尔激子表现出强烈的谷相干性，由于运动变窄，它以惊人的非单调 W 形变化并带有门控。
更新日期：2022-06-09
中文翻译：
扭曲的 MoS2 双层中的电可调局部与离域层内莫尔激子和三角子
扭曲范德瓦尔斯同质结构和异质结构中莫尔超晶格 (mSL) 诱导的子带控制着它们的光学和电学特性，从而提供额外的自由度，例如扭曲角。在这里，我们展示了莫尔超晶格对 MoS 2扭曲双层中层内激子和三重子的影响边缘扭转角的 H 型堆叠。我们确定了层内莫尔激子的局域化和离域子带的发射，并通过相应的 trion 形成显示它们的电调制。莫尔激子的振荡器强度的电气控制也导致共振拉曼散射的强可调谐性。我们发现栅极诱导掺杂显着调节了电子莫尔电位；然而，激子云纹限制没有改变。这种效应，加上通过调整光激发密度来填充可变波纹陷阱，使我们能够描绘出局部和离域波纹三重子的不同阶段。我们证明了莫尔激子表现出强烈的谷相干性，由于运动变窄，它以惊人的非单调 W 形变化并带有门控。
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