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Start Over Author "Gao, Weibo" Journal nano letters
22 results on '"Gao, Weibo"'

3. Room-Temperature Geometrical Circular Photocurrent in Few-Layer MoS2

Author

Li, Ziqi, Liu, Jiayun, Rasmita, Abdullah, Zhang, Zhaowei, Gao, Weibo, and Chia, Elbert E. M.

Abstract

Valleytronics, i.e., the manipulation of the valley degree of freedom, offers a promising path for energy-efficient electronics. One of the key milestones in this field is the room-temperature manipulation of the valley information in thick-layered material. Using scanning photocurrent microscopy, we achieve this milestone by observing a geometrically dependent circular photocurrent in a few-layer molybdenum disulfide (MoS2) under normal incidence. Such an observation shows that the system symmetry is lower than that of bulk MoS2material, preserving the optical chirality–valley correspondence. Moreover, the circular photocurrent polarity can be reversed by applying electrical bias. We propose a model where the observed photocurrent results from the symmetry breaking and the built-in field at the electrode–sample interface. Our results show that the valley information is still retained even in thick-layered MoS2at room temperature and opens up new opportunities for exploiting the valley index through interface engineering in multilayer valleytronics devices.

Published
2024
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11. Chiral Phonon Diode Effect in Chiral Crystals

Author

Chen, Hao, primary, Wu, Weikang, additional, Zhu, Jiaojiao, additional, Yang, Zhengning, additional, Gong, Weikang, additional, Gao, Weibo, additional, Yang, Shengyuan A., additional, and Zhang, Lifa, additional

Published
2022
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12. Donor–Acceptor Pair Quantum Emitters in Hexagonal Boron Nitride

Author

Tan, Qinghai, primary, Lai, Jia-Min, additional, Liu, Xue-Lu, additional, Guo, Dan, additional, Xue, Yongzhou, additional, Dou, Xiuming, additional, Sun, Bao-Quan, additional, Deng, Hui-Xiong, additional, Tan, Ping-Heng, additional, Aharonovich, Igor, additional, Gao, Weibo, additional, and Zhang, Jun, additional

Published
2022
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15. Coherent Manipulation with Resonant Excitation and Single Emitter Creation of Nitrogen Vacancy Centers in 4H Silicon Carbide

Author

Mu, Zhao, primary, Zargaleh, Soroush Abbasi, additional, von Bardeleben, Hans Jürgen, additional, Fröch, Johannes E., additional, Nonahal, Milad, additional, Cai, Hongbing, additional, Yang, Xinge, additional, Yang, Jianqun, additional, Li, Xingji, additional, Aharonovich, Igor, additional, and Gao, Weibo, additional

Published
2020
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19. Robust Room Temperature Valley Hall Effect of Interlayer Excitons

Author

Huang, Zumeng, Liu, Yuanda, Dini, Kévin, Tan, Qinghai, Liu, Zhuojun, Fang, Hanlin, Liu, Jin, Liew, Timothy, and Gao, Weibo

Abstract

The Berry curvature in the band structure of transition metal dichalcogenides (TMDs) introduces a valley-dependent effective magnetic field, which induces the valley Hall effect (VHE). Similar to the ordinary Hall effect, the VHE spatially separates carriers or excitons, depending on their valley index, and accumulates them at opposite sample edges. The VHE can play a key role in valleytronic devices, but previous observations of the VHE have been limited to cryogenic temperatures. Here, we report a demonstration of the VHE of interlayer excitons in a MoS2/WSe2heterostructure at room temperature. We monitored the in-plane propagation of interlayer excitons through photoluminescence mapping and observed their spatial separation into two opposite transverse directions that depended on the valley index of the excitons. Our theoretical simulations reproduced the salient features of these observations. Our demonstration of the robust interlayer exciton VHE at room temperature, enabled by their intrinsically long lifetimes, will open up realistic possibilities for the development of opto-valleytronic devices based on TMD heterostructures.

Published
2020
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21. Spatial Filtering of Interlayer Exciton Ground State in WSe2/MoS2Heterobilayer

Author

Chen, Disheng, Dini, Kevin, Rasmita, Abdullah, Huang, Zumeng, Tan, Qinghai, Cai, Hongbing, He, Ruihua, Miao, Yansong, Liew, Timothy C. H., and Gao, Weibo

Abstract

Long-life interlayer excitons (IXs) in transition metal dichalcogenide (TMD) heterostructure are promising for realizing excitonic condensates at high temperatures. Critical to this objective is to separate the IX ground state (the lowest energy of IX state) emission from other states’ emissions. Filtering the IX ground state is also essential in uncovering the dynamics of correlated excitonic states, such as the excitonic Mott insulator. Here, we show that the IX ground state in the WSe2/MoS2heterobilayer can be separated from other states by its spatial profile. The emissions from different moiré IX modes are identified by their different energies and spatial distributions, which fits well with the rate-diffusion model for cascading emission. Our results show spatial filtering of the ground state mode and enrich the toolbox to realize correlated states at elevated temperatures.

Published
2024
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22. Spectral Fingerprint of Quantum Confinement in Single CsPbBr 3 Nanocrystals.

Author

Amara MR, Said Z, Huo C, Pierret A, Voisin C, Gao W, Xiong Q, and Diederichs C

Abstract

Lead halide perovskite nanocrystals are promising materials for classical and quantum light emission. To understand these outstanding properties, a thorough analysis of the band-edge exciton emission is needed, which is not reachable in ensemble and room-temperature studies because of broadening effects. Here, we report on a cryogenic-temperature study of the photoluminescence of single CsPbBr 3 nanocrystals in the intermediate quantum confinement regime. We reveal the size-dependence of the spectral features observed: the bright triplet exciton energy splittings, the trion and biexciton binding energies, and the optical phonon replica spectrum. In addition, we show that bright triplet energy splittings are consistent with a pure exchange model and that the variety of polarization properties and spectra recorded can be rationalized simply by considering the orientation of the emitting dipoles and the populations of the emitting states.

Published
2023
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