Article
Nanoscience & Nanotechnology
Po-Liang Chen, Yueyang Chen, Tian-Yun Chang, Wei-Qing Li, Jia-Xin Li, Seokhyeong Lee, Zhuoran Fang, Mo Li, Arka Majumdar, Chang-Hua Liu
Summary: The extension of the operation wavelength of silicon photonics to the mid-infrared band is of great importance for fields such as health care, astronomy, and chemical sensing. However, a major challenge for mid-IR silicon photonics has been the lack of high-speed, high-responsivity, and low noise-equivalent power photodetectors. In this study, researchers demonstrated a van der Waals heterostructure mid-IR photodetector integrated on a silicon-on-insulator waveguide, which exhibited high responsivity and stable switching performance.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Guanghui Wang, Bin Han, Chun Hong Mak, Jialong Liu, Bo Liu, Peng Liu, Xiaodong Hao, Hongyue Wang, Shufang Ma, Bingshe Xu, Hsien-Yi Hsu
Summary: This study demonstrates a photodetector with a mixed-dimensional van der Waals heterostructure of hBN/Gr/1D CH3NH3PbI3, which shows improved carrier extraction, excellent responsivity, and specific detectivity. The device also exhibits high stability when exposed to air due to the atomic encapsulation of hBN.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Yuehui Wang, Yuqing Tang, Haoran Li, Zhibin Yang, Qingyi Zhang, Zhenbei He, Xu Huang, Xianhua Wei, Weihua Tang, Wen Huang, Zhenping Wu
Summary: A solar-blind photodetector is developed by combining GaSe flakes with Ga2O3 epitaxial films, showing high sensitivity to solar-blind ultraviolet light, fast response speed, and superior figures of merit compared to most reported Ga2O3-based photodetectors. The potential of GaSe/Ga2O3 van der Waals heterojunction for next-generation, solar-blind photodetectors is revealed in this work.
Article
Chemistry, Multidisciplinary
Wanhan Su, Sen Zhang, Chang Liu, Qianlei Tian, Xingqiang Liu, Kenli Li, Yawei Lv, Lei Liao, Xuming Zou
Summary: This study demonstrates a 2D PVK and ReS2 heterostructure with high sensitivity and broad spectral response. The strong interlayer coupling and large type-II band offsets contribute to the improved performance of the heterostructure, making it a promising candidate for self-driven photodetectors.
Article
Chemistry, Analytical
Seyedali Hosseini, Azam Iraji Zad, Seyed Mohammad Mahdavi, Ali Esfandiar
Summary: A tunable gain SnS2/InSe Van der Waals heterostructure photodetector was studied, utilizing the favorable properties of two-dimensional materials such as SnS2 and InSe. The device showed high photoresponsivity and detectivity, making it a potential candidate for commercial visible image sensors.
Article
Chemistry, Physical
Jinping Chen, Zhen Zhang, Yi Ma, Jiying Feng, Xiaoyu Xie, Xiaoxuan Wang, Aoqun Jian, Yuanzheng Li, Zhuxin Li, Heng Guo, Yizhi Zhu, Qiannan Cui, Zengliang Shi, Chunxiang Xu
Summary: A WS2/InSe van der Waals heterostructure (vdWH) photodiode was fabricated by stacking InSe and WS2 flakes using an all-dry transfer method. The heterostructure exhibited excellent photovoltaic behavior with a large open voltage, short-circuit current, fast response time, high light on/off ratio, high responsivity, and broadband photoresponse. This study provides a strategy for developing high-performance self-powered broadband photodetectors based on 2D materials.
Article
Chemistry, Physical
Jinping Chen, Zhen Zhang, Yi Ma, Jiying Feng, Xiaoyu Xie, Xiaoxuan Wang, Aoqun Jian, Yuanzheng Li, Zhuxin Li, Heng Guo, Yizhi Zhu, Qiannan Cui, Zengliang Shi, Chunxiang Xu
Summary: This study presents a WS2/InSe vdWH photodiode based on 2D materials, which exhibits excellent photovoltaic behavior and broadband photoresponse due to the precise stacking and energy-band alignment.
Article
Chemistry, Multidisciplinary
Qiao Zhang, Bijun Zhao, Siqi Hu, Ruijuan Tian, Chen Li, Liang Fang, Yong Zhang, Yan Liu, Jianlin Zhao, Xuetao Gan
Summary: In this study, a high-performance photodetector based on a van der Waals heterostructure is proposed, which integrates p-type black phosphorus and n-type molybdenum disulfide on a silicon nitride photonic platform. Efficient carrier separation and dark current suppression at the junction interface of the heterostructure enable high photodetectivity and fast response speed.
Article
Nanoscience & Nanotechnology
Tian-Yun Chang, Po-Liang Chen, Pei-Sin Chen, Wei-Qing Li, Jia-Xin Li, Ming-Yuan He, Jen-Te Chao, Ching-Hwa Ho, Chang-Hua Liu
Summary: This study demonstrates the potential of using band-engineered van der Waals hetero-structures as bias-selectable photodetectors. By tuning the bias polarity, the spectral photoresponse can be switched between different bands, showing high external quantum efficiency and fast operation speed.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Zhiying Dan, Baoxiang Yang, Qiqi Song, Jianru Chen, Hengyi Li, Wei Gao, Le Huang, Menglong Zhang, Mengmeng Yang, Zhaoqiang Zheng, Nengjie Huo, Lixiang Han, Jingbo Li
Summary: In recent years, the development of 2D nonlayered Bi2O2Se-based electronics and optoelectronics has attracted great attention due to their high electron mobility, stability, and narrow band gaps. However, conventional Bi2O2Se-based photodetectors suffer from issues such as high dark current, slow response speed, and persistent photoconductivity effect, limiting their applications in fast-response imaging sensors and low-power broadband detection. In this study, a Bi2O2Se/2H-MoTe2 van der Waals heterostructure is reported, which shows improved performance in terms of responsivity, detectivity, and conversion efficiency. The proposed heterostructure is considered a promising candidate for integrated circuits, image sensors, and low-power detection.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Multidisciplinary Sciences
Long Zhang, Fengcheng Wu, Shaocong Hou, Zhe Zhang, Yu-Hsun Chou, Kenji Watanabe, Takashi Taniguchi, Stephen R. Forrest, Hui Deng
Summary: Controlling matter-light interactions with cavities is crucial in modern science and technology. By integrating MoSe2-WS2 heterobilayers in a microcavity, cooperative coupling between moire-lattice excitons and microcavity photons has been established, providing versatile control of both matter and light. This moire polariton system combines strong nonlinearity and microscopic-scale tuning of matter excitations, offering a platform to study collective phenomena from tunable arrays of quantum emitters.
Article
Chemistry, Physical
Huide Wang, Yonghong Zeng, FanXu Meng, Rui Cao, Yi Liu, Zhinan Guo, Tingting Wang, Haiguo Hu, Sidi Fan, Yatao Yang, S. Wageh, Omar A. Al-Hartomy, Abul Kalam, Yonghong Shao, Yu-Jia Zeng, Dianyuan Fan, Han Zhang
Summary: A black phosphorus/rhodamine 6G/molybdenum disulfide (BP/R6G/MoS2) photodiode with high responsivity has been achieved by utilizing interfacial charge transfer of R6G molecules between heterojunction layers. The formed vdWs interface efficiently separates the additional photogenerated electrons and holes generated by R6G molecules, resulting in high-performance photoresponse. By sensitizing the devices with the dye molecule R6G, enhanced photodetection performance is obtained without sacrificing the photoresponse speed, with R increasing by 14.8-20.4 times and specific detectivity (D*) increasing by 24.9-34.4 times. The proposed strategy of interlayer assembly of dye molecules may pave a new way for high-performance photodetection based on 2D vdWs heterojunctions with high responsivity and fast response speed.
Article
Chemistry, Multidisciplinary
Ha-Leem Kim, Feng Wang
Summary: Reflective phase-contrast microscopy provides high contrast for imaging transparent 2D monolayers and allows direct observation of embedded monolayers in thick heterostructures that are invisible in conventional microscopy. It achieves this by flexibly controlling the intensity and phase of both the illumination and reflected light using spatial light modulators.
Article
Chemistry, Multidisciplinary
Shuangjie Liu, Ling Liu, Yue Zhao, Yang Wang, Yingpeng Wu, Xiao-Dong Zhang, Dong Ming
Summary: A neural electrode based on the graphene/Ag heterostructure has been developed to improve the detection sensitivity and signal-to-noise ratio of neural signals. Experimental results show that the impedance of the graphene/Ag electrode is reduced and the charge-storage capacity is increased, leading to significant improvement in in vivo detection sensitivity and SNR.
Article
Chemistry, Multidisciplinary
Yafei Yan, Minxin Li, Kai Xia, Kemeng Yang, Dun Wu, Liang Li, Guangtao Fei, Wei Gan
Summary: Researchers fabricated a van der Waals heterostructure (vdWH) photodetector composed of rhenium disulfide (ReS2) and tellurium (Te), which exhibited a sensitive and broadband photoresponse with high on/off ratios. The photodetector achieved high responsivity and specific detectivity, as well as a fast photoresponse speed. Additionally, it showed a photovoltaic effect and could be used as a self-powered photodetector (SPPD).
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.