Article
Chemistry, Multidisciplinary
Veronica R. Policht, Mattia Russo, Fang Liu, Chiara Trovatello, Margherita Maiuri, Yusong Bai, Xiaoyang Zhu, Stefano Dal Conte, Giulio Cerullo
Summary: This study utilized two-dimensional electronic spectroscopy (2DES) to resolve interlayer electron and hole transfer processes in WS2/MoS2 heterostructures, while simultaneously uncovering optoelectronic processes such as band gap renormalization and intralayer exciton coupling.
Article
Chemistry, Multidisciplinary
Arka Karmakar, Abdullah Al-Mahboob, Christopher E. Petoukhoff, Oksana Kravchyna, Nicholas S. Chan, Takashi Taniguchi, Kenji Watanabe, Keshav M. Dani
Summary: This study shows that nonradiative energy transfer dominates over interlayer charge transfer in type-II heterostructures formed by transition metal dichalcogenides. It also demonstrates an innovative way to increase the photoluminescence intensity of desired materials by carefully choosing the right material combination.
Article
Chemistry, Multidisciplinary
Daniel Hernangomez-Perez, Amir Kleiner, Sivan Refaely-Abramson
Summary: In this study, the effect of defects on the electronic and optical properties of WS2-graphene and MoS2-graphene van der Waals heterobilayers was investigated using many-body perturbation theory. It was found that chalcogen defects and the graphene interface significantly alter the optical properties of the transition-metal dichalcogenide in the heterobilayer. The introduction of defects leads to low-energy optical transitions and excitons with non-negligible oscillator strength, while decreasing the optical response of the pristine-like transition-metal dichalcogenide intralayer excitons. These findings provide insights into interface design for defect engineering in photovoltaic and transport applications.
Article
Multidisciplinary Sciences
Elyse Barre, Ouri Karni, Erfu Liu, Aidan L. O'Beirne, Xueqi Chen, Henrique B. Ribeiro, Leo Yu, Bumho Kim, Kenji Watanabe, Takashi Taniguchi, Katayun Barmak, Chun Hung Lui, Sivan Refaely-Abramson, Felipe H. da Jornada, Tony F. Heinz
Summary: Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. The dielectric response of interlayer excitons was directly measured using their static electric dipole moment, and an intrinsic radiative lifetime and transition characteristics were determined. This study identifies a momentum-indirect emission mechanism and emphasizes the importance of characterizing absorption for applications relying on light-matter interactions.
Article
Chemistry, Physical
Xu Wu, Jingsi Qiao, Liwei Liu, Yan Shao, Zhongliu Liu, Linfei Li, Zhili Zhu, Cong Wang, Zhixin Hu, Wei Ji, Yeliang Wang, Hongjun Gao
Summary: The study proposed a technique to suppress carrier traps at the interface of TMD heterostructures by using enhanced interlayer hybridization, effectively addressing the issue of charge flow in the two-dimensional electronic community.
Article
Chemistry, Physical
Biao Wu, Haihong Zheng, Junnan Ding, Yunpeng Wang, Zongwen Liu, Yanping Liu
Summary: Vertically stacked transition metal dichalcogenide (TMD) heterostructures provide an opportunity to explore optoelectronic properties within the two-dimensional limit. In this study, we observed interlayer excitons (IXs) in trilayer type-II staggered band alignment heterostructures. We studied the properties and dependence of IXs through experiments and calculations, and also investigated their polarization characteristics.
Review
Chemistry, Physical
Jian Tang, Yue Zheng, Ke Jiang, Qi You, Zhentian Yin, Zihao Xie, Henan Li, Cheng Han, Xiaoxian Zhang, Yumeng Shi
Summary: Stacking single layers of atoms to create novel material systems and engineer their physical properties is a fundamental approach. Transition metal dichalcogenide (TMDC) heterostructures, with their tightly-bonded interlayer excitons, offer promising opportunities for unique optoelectronic devices. This review summarizes recent advances in understanding the behavior of interlayer excitons in TMDC heterostructures under electric fields, with emphasis on their emission modulation, valley Hall transport, and correlation physics. Challenges and perspectives for future optoelectronics using TMDC heterostructures are discussed.
Article
Chemistry, Multidisciplinary
Simrjit Singh, Weiyi Gong, Christopher E. Stevens, Jin Hou, Aditya Singh, Huiqin Zhang, Surendra B. Anantharaman, Aditya D. Mohite, Joshua R. Hendrickson, Qimin Yan, Deep Jariwala
Summary: This article investigates the interlayer exciton phenomenon in two-dimensional heterostructures, and demonstrates the observation of helicity-resolved interlayer excitons through spin-valley layer coupling. This method does not require a specific geometric arrangement, such as twist angle or thermal annealing. The research shows that there are spin-valley-dependent optical selection rules in two-dimensional perovskites and monolayer transition metal dichalcogenides.
Article
Chemistry, Multidisciplinary
Amir Muhammad Afzal, Muhammad Zahir Iqbal, Ghulam Dastgeer, Aqrab ul Ahmad, Byoungchoo Park
Summary: A novel vdWH FET composed of MoTe2 and PdSe2 has been studied for highly sensitive photodetection performance in the visible and near-infrared region, showing high rectification ratio, photoresponsivity, detectivity, and external quantum efficiency. The device exhibits rapid rise and decay times under incident light due to inter-TMD charge transfer transition, representing an outcome one order of magnitude faster than current literature values. These TMD-based vdWH FETs would improve photo-gating characteristics and provide a platform for highly sensitive photodetectors in the broad VNIR region.
Article
Chemistry, Multidisciplinary
Saloni Kakkar, Aniket Majumdar, Tanweer Ahmed, Aparna Parappurath, Navkiranjot Kaur Gill, Kenji Watanabe, Takashi Taniguchi, Arindam Ghosh
Summary: Researchers have utilized the bidirectionality of interlayer charge transfer in binary van der Waals heterostructures of graphene and transition metal dichalcogenide to detect sub-band gap photons, achieving fast and repeatable detection of low energy photons with a photoresponsivity of approximately 3000 A W-1.
Article
Chemistry, Multidisciplinary
Shuangyan Liu, Dawei He, Congwei Tan, Shaohua Fu, Xiuxiu Han, Mohan Huang, Qing Miao, Xiaoxian Zhang, Yongsheng Wang, Hailin Peng, Hui Zhao
Summary: Research on the interlayer charge transfer properties of heterostructures formed by Bi2O2Se and WS2/MoS2 showed photoluminescence quenching and ultrafast charge transfer processes. These results demonstrate the feasibility of integrating 2D Bi2O2Se with other 2D semiconductors to fabricate heterostructures with novel charge transfer properties.
Article
Materials Science, Multidisciplinary
S. J. Magorrian, A. J. Graham, N. Yeung, F. Ferreira, P. Nguyen, A. Barinov, V. Fal'ko, N. R. Wilson, N. D. M. Hine
Summary: In this work, the relative alignment and hybridization of bands in van der Waals heterostructures of transition metal dichalcogenides (TMDs) and hexagonal boron nitride (hBN) are studied. By comparing density functional calculations with experimental angle-resolved photoemission spectroscopy (ARPES) results, the hybridization between TMD and hBN valence states and its effects on band crossings are explored.
Article
Chemistry, Multidisciplinary
Ting Zheng, Yu-Chuan Lin, Neema Rafizadeh, David B. Geohegan, Zhenhua Ni, Kai Xiao, Hui Zhao
Summary: The charge transfer properties of van der Waals heterostructures formed by Janus and regular transition metal dichalcogenide monolayers have been studied. It is found that the charge transfer from regular to Janus monolayers is ultrafast, regardless of the direction of the Janus field. However, the charge transfer from Janus to regular layers is directional and controlled by the Janus field. The transferred carriers form interlayer excitons with extended lifetimes compared to intralayer excitons. These findings indicate that Janus structures can be utilized to create 2D heterostructures with efficient and directional charge transfer properties.
Article
Nanoscience & Nanotechnology
Ting Zheng, Pavel Valencia-Acuna, Peymon Zereshki, Katherine M. Beech, Lier Deng, Zhenhua Ni, Hui Zhao
Summary: The study reveals a strong thickness dependence for charge transfer from MoSe2 to MoS2, with longer transfer times and extended interlayer exciton recombination lifetimes observed in thicker heterostructures. The results suggest that layer thickness is an important parameter for controlling the CT properties of van der Waals heterostructures, providing valuable insights for understanding the physical mechanisms of charge transfer in these systems.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Haihong Zheng, Hongli Guo, Shula Chen, Biao Wu, Shaofei Li, Jun He, Zongwen Liu, Gang Lu, Xidong Duan, Anlian Pan, Yanping Liu
Summary: WSe2/WSe2 homobilayers with different twist angles were synthesized using a heteroatom-assisted chemical vapor deposition (CVD) technique. The uniformity of the moire superlattices in the homobilayers fabricated by CVD was mapped using low-frequency Raman scattering, demonstrating strong interfacial coupling. The moire potential depths of the CVD-grown and artificially stacked homostructures with a twist angle of 1.5 degrees were 115 and 45 meV (an increase of 155%), indicating the modulation of moire potential depth through interfacial coupling.
ADVANCED MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Aditya Sood, Jonah B. Haber, Johan Carlstrom, Elizabeth A. Peterson, Elyse Barre, Johnathan D. Georgaras, Alexander H. M. Reid, Xiaozhe Shen, Marc E. Zajac, Emma C. Regan, Jie Yang, Takashi Taniguchi, Kenji Watanabe, Feng Wang, Xijie Wang, Jeffrey B. Neaton, Tony F. Heinz, Aaron M. Lindenberg, Felipe H. da Jornada, Archana Raja
Summary: In this study, lattice dynamics in photoexcited WSe2/WS2 heterostructures were directly visualized using femtosecond electron diffraction. It was found that both WSe2 and WS2 were heated simultaneously on a picosecond timescale, which cannot be explained by phonon transport across the interface. First-principles calculations revealed a fast channel involving layer-hybridized electronic states, enabling phonon-assisted interlayer transfer of photoexcited electrons. Phonons were emitted in both layers on the femtosecond timescale via this channel, consistent with the simultaneous lattice heating observed experimentally. Strong electron-phonon coupling via layer-hybridized electronic states was identified as a novel route for controlling energy transport across atomic junctions.
NATURE NANOTECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Jonas D. D. Ziegler, Yeongsu Cho, Sophia Terres, Matan Menahem, Takashi Taniguchi, Kenji Watanabe, Omer Yaffe, Timothy C. C. Berkelbach, Alexey Chernikov
Summary: 2D hybrid perovskites have attracted significant attention in material research for light-harvesting and -emitting applications. In this study, a method of interfacing ultrathin sheets of perovskites with few-layer graphene and hexagonal boron nitride is demonstrated, enabling gate-tunable control of light emission and absorption. The findings reveal the emergence of both negatively and positively charged excitons, with high binding energies and excellent mobility. This research introduces the physics of interacting mixtures of optical and electrical excitations to the broad family of 2D inorganic-organic nanostructures, highlighting the potential of 2D perovskites as a promising material platform for electrically modulated light-emitters and exciton transistors.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Minwook Kim, Yeonjae Lee, Sunil Kumar, Dongwoon Kang, Sohee Lee, Van Huy Nguyen, Dinh Cong Nguyen, Syed Hassan Abbas Jaffery, Jongwan Jung, Takashi Taniguchi, Kenji Watanabe, Yongho Seo
Summary: In recent years, there has been extensive research on 2D materials-based heterostructures for fabricating nanodevices. Transition metal dichalcogenides (TMDC), hexagonal boron nitride (hBN), and graphene (Gr) are commonly used materials in these devices. Optoelectronic memory devices based on 2D materials are of particular interest due to their structural flexibility and small device size. This study focuses on the fabrication of a non-volatile optoelectronic memory device using tungsten diselenide (WSe2) and hBN-encapsulated Gr-based heterostructures. The device can be easily controlled by both UV light and an electric field.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Multidisciplinary
Valerie Hsieh, Dorri Halbertal, Nathan R. . Finney, Ziyan Zhu, Eli Gerber, Michele Pizzochero, Emine Kucukbenli, Gabriel R. Schleder, Mattia Angeli, Kenji Watanabe, Takashi Taniguchi, Eun-Ah Kim, Efthimios Kaxiras, James Hone, Cory R. Dean, D. N. Basov
Summary: Twisted van der Waals multilayers are regarded as a rich platform for accessing novel electronic phases. This study proposes that naturally formed stacking domains due to relative twist between layers can act as an additional control knob. The researchers observe selective adhesion of metallic nanoparticles and liquid water at domains with specific stacking configurations and demonstrate the manipulation of nanoparticles can locally reconfigure the moire superlattice.
Article
Chemistry, Multidisciplinary
Yu-Chiang Hsieh, Zhen-You Lin, Shin-Ji Fung, Wen-Shin Lu, Sheng-Chin Ho, Siang-Ping Hong, Sheng-Zhu Ho, Chiu-Hua Huang, Kenji Watanabe, Takashi Taniguchi, Yang-Hao Chan, Yi-Chun Chen, Chung-Lin Wu, Tse-Ming Chen
Summary: By creating atomically flat surface nanostructures in hexagonal boron nitride, we achieve an arbitrary on-chip control of both the strain distribution and magnitude on high-quality molybdenum disulfide. The phonon and exciton emissions vary according to our strain field designs, enabling us to write and draw any photoluminescence color image in a single chip. Our strain engineering also offers a powerful means to alter the strengths and energies of interlayer excitons at room temperature, promising for functional excitonic devices.
Article
Chemistry, Physical
Benjamin A. Foutty, Jiachen Yu, Trithep Devakul, Carlos R. Kometter, Yang Zhang, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Benjamin E. Feldman
Summary: By studying twisted double-bilayer WSe2, we have identified charge-ordered phases at multiple integer and fractional moire fillings. Through experiments with magnetic fields and displacement fields, we have observed spin-polarized ground states and a metal-insulator transition. These results demonstrate the control over spin and valley character in this system.
Article
Multidisciplinary Sciences
Kaining Yang, Xiang Gao, Yaning Wang, Tongyao Zhang, Yuchen Gao, Xin Lu, Shihao Zhang, Jianpeng Liu, Pingfan Gu, Zhaoping Luo, Runjie Zheng, Shimin Cao, Hanwen Wang, Xingdan Sun, Kenji Watanabe, Takashi Taniguchi, Xiuyan Li, Jing Zhang, Xi Dai, Jian-Hao Chen, Yu Ye, Zheng Han
Summary: The authors report the evidence of unconventional correlated insulating states in bilayer graphene/CrOCl heterostructures and demonstrate their application for low-temperature logic inverters. They investigate the heterostructures based on Bernal-stacked bilayer graphene atop few-layered CrOCl, which exhibit an over-1-G omega-resistance insulating state in a widely accessible gate voltage range. By applying an in-plane electric field, heating, or gating, the insulating state can be switched into a metallic state with an on/off ratio up to 10(7).
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Salvatore Cianci, Elena Blundo, Federico Tuzi, Giorgio Pettinari, Katarzyna Olkowska-Pucko, Eirini Parmenopoulou, Djero B. L. Peeters, Antonio Miriametro, Takashi Taniguchi, Kenji Watanabe, Adam Babinski, Maciej R. Molas, Marco Felici, Antonio Polimeni
Summary: This paper reports the formation of regular arrays of strained hydrogen-filled one-layer-thick micro-domes by H-ion irradiation and lithography-based approaches. By depositing thin hBN flakes on the domes, the dome structure can be preserved, leading to the appearance of intense emission lines from localized excitons, which behave as quantum emitters.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Michael D. Randle, Masayuki Hosoda, Russell S. Deacon, Manabu Ohtomo, Patrick Zellekens, Kenji Watanabe, Takashi Taniguchi, Shota Okazaki, Takao Sasagawa, Kenichi Kawaguchi, Shintaro Sato, Koji Ishibashi
Summary: Systems combining superconductors with topological insulators provide a platform for studying Majorana bound states and realizing fault tolerant topological quantum computation. Monolayers of WTe2 possess rare properties, such as being a quantum spin Hall insulator and easily transitioning into a superconducting state. Measurements on gate-defined Josephson weak-link devices made from monolayer WTe2 demonstrate the critical role of 2D superconducting leads in interpreting magnetic interference in the resulting junctions. The reported fabrication procedures offer a straightforward means of producing more devices from this technically challenging material and mark the first step towards versatile all-in-one topological Josephson weak-links using monolayer WTe2.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Rafael Battistella Nadas, Andreij C. Gadelha, Tiago C. Barbosa, Cassiano Rabelo, Thiago de Lourenco e Vasconcelos, Vitor Monken, Ary V. R. Portes, Kenji Watanabe, Takashi Taniguchi, Jhonattan C. Ramirez, Leonardo C. Campos, Riichiro Saito, Luiz Gustavo Cancado, Ado Jorio
Summary: The coherence length (L(c)) of the Raman scattering process in graphene, as determined by spatially coherent tip-enhanced Raman spectroscopy, decreases when the Fermi energy is brought to the neutrality point. This observation is consistent with the concept of the Kohn anomaly within a ballistic transport regime. The observed results can be attributed to either an unusually large variation in the longitudinal optical phonon group velocity (v(g)), which reaches twice the value of the longitudinal acoustic phonon, or changes in the electron energy uncertainty. These properties are important for understanding optical and transport phenomena that may not be observable with other techniques.
Editorial Material
Multidisciplinary Sciences
Qian Song, Connor A. Occhialini, Emre Ergecen, Batyr Ilyas, Danila Amoroso, Paolo Barone, Jesse Kapeghian, Kenji Watanabe, Takashi Taniguchi, Antia S. Botana, Silvia Picozzi, Nuh Gedik, Riccardo Comin
Article
Optics
Tianqi Liu, Qiang Fu, Yuanzhe Li, Xu Han, Shixuan Wang, Takashi Taniguchi, Kenji Watanabe, Dongyang Wan, Qi Zhang, Yingbo Zhao, Zhenhua Ni, Fei Ding, Zhenliang Hu, Xueyong Yuan, Junpen Lu
Summary: In this study, the brightness of WS2-based LEDs is enhanced by introducing self-assembled silver nanoparticles (NPs) on top of the LED. With the assistance of effective transient-mode charge injection, a 2.9-fold electroluminescence (EL) enhancement is observed in the experiment. Full-wave simulations confirm that the improvement comes from the scattering capability of silver NPs.
Article
Optics
Garima Gupta, Kenji Watanabe, Takashi Taniguchi, Kausik Majumdar
Summary: In monolayer transition metal dichalcogenide semiconductors, valley coherence degrades rapidly due to scattering and inter-valley exchange interaction. However, by using a sandwich structure of monolayer MoS2 between top and bottom graphene, fully valley-coherent excitons with high degree of linear polarization are achieved. This is attributed to the suppression in exchange interaction, reduction in exciton lifetime, and operating in the motional narrowing regime.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Shaochun Zhang, Mina Maruyama, Susumu Okada, Mengsong Xue, Kenji Watanabe, Takashi Taniguchi, Kazuki Hashimoto, Yasumitsu Miyata, Ruben Canton-Vitoria, Ryo Kitaura
Summary: This study reports the observation of the photovoltaic effect in a WS2/MoS2 van der Waals heterostructure. Light excitation of WS2/MoS2 at a wavelength of 633 nm leads to a photocurrent without applying bias voltages.
Article
Chemistry, Multidisciplinary
Aparna Parappurath, Bhaskar Ghawri, Saisab Bhowmik, Arup Singha, K. Watanabe, T. Taniguchi, Arindam Ghosh
Summary: The ability to tune the twist angle between different layers of 2D materials has led to the creation of electronic flat bands artificially. In this study, the photoresponse of a few-layer WSe2/tBLG heterostructure was measured, and it was found that the photoresponse is sensitive to the band structure of tBLG. When the Fermi energy is within the low-energy moiré bands, the photoresponse is strongly suppressed, but it can be recovered when the Fermi energy exceeds the moiré band edge due to the photogating effect.