Article
Chemistry, Physical
Zhao Wei, Songyang Xie, Wei Xiong, Shuwen Zen, Dong Chen, Tao Jiang, Da Chen, Jun Zhou, Chenjie Gu
Summary: Surface-enhanced Raman scattering (SERS) is a non-destructive spectral analysis technique with high detectivity and sensitivity. This research demonstrates significantly improved SERS performance using MoS2/MoOx heterostructures. The optimized SERS substrate was obtained after 14 hours of ultraviolet-ozone irradiation, exhibiting a detection limit of 10(-7) M (rhodamine 6G) and an enhancement factor of 7.477 x 10(6) (R6G@10(-7) M). By analyzing the energy band, it was found that the heterostructures enhanced electron-hole separation and promoted molecular polarizability, thereby improving SERS performance.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Soumyajit Sarkar, Peter Kratzer
Summary: In this study, atomic structures at the interface between Au(111) and monolayers of MoS2 and MoSe2 were investigated using first-principles calculations. The focus was on calculating vibrational spectra and comparing them to experimental data. MoSe2 monolayers showed minimal shifts in vibrational modes upon adsorption on Au(111), while MoS2 exhibited the coexistence of two structural models with different characteristics.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Paolo D'Agosta, Francesco Tumino, Valeria Russo, Andrea Li Bassi, Carlo S. Casari
Summary: In this work, the growth of WS2/MoS2 and MoS2/WS2 heterobilayers by pulsed laser deposition (PLD) under ultra-high vacuum conditions was studied. The heterobilayer morphology and structure at the nanoscale were investigated using in situ scanning tunneling microscopy. The experiments showed that the growth of the heterostructure can be controlled by tuning the number of laser pulses, achieving high coverage and thickness sensitivity. Raman spectroscopy revealed the effect of the interaction with the metallic substrate on the TMD vibrational properties and a strong interlayer coupling between the MoS2 and WS2 layers. The transfer of the heterobilayers onto a silica substrate confirmed that the interlayer coupling is not substrate-dependent. This work highlights the potential of PLD technique in growing TMD heterostructures and opens new perspectives in the synthesis of complex 2D layered materials.
Article
Chemistry, Physical
Lishu Wu, Chunxiao Cong, Jingzhi Shang, Weihuang Yang, Yu Chen, Jiadong Zhou, Wei Ai, Yanlong Wang, Shun Feng, Hongbo Zhang, Zheng Liu, Ting Yu
Summary: In twisted WS2/MoS2 heterostructures, the shifts and linewidths of E-2g(Gamma) and A(1g)(Gamma) phonon modes are found to be twist angle dependent, primarily due to spacing-related repulsion between sulfur atoms. Additionally, opposite shift behaviors and broadening of A(1g)(Gamma) modes caused by charge transfer are also observed in the twisted heterostructures. The understanding and controlling of interlayer interaction through the stacking orientation are crucial for the future design of optoelectronic devices based on 2D heterostructures.
Article
Chemistry, Multidisciplinary
Ravindra Kumar, Vikash Mishra, Tejendra Dixit, Prahalad Kanti Barman, Pramoda K. Nayak, M. S. Ramachandra Rao
Summary: Mono-layer transition metal dichalcogenides (TMDCs) are promising materials for studying many-body physics due to their low dimensionality and strong Coulomb interaction. The van der Waals (vdW) heterostructures (HSs) of TMDCs provide an additional degree of freedom for altering the properties of 2D materials. In this study, vdW HSs (& alpha;-MoO3/MoS2) were synthesized and their temperature-dependent photoluminescence (PL) spectra were investigated. The emergence of a new PL peak in the low-energy regime was attributed to the formation of a positive trion, which was confirmed by power and wavelength-dependent Raman and PL studies.
Article
Optics
Jingyu Wang, Weimin Yang, Guoya Sun, Yonglin He, Peiwen Ren, Zhilin Yang
Summary: This work demonstrates a strong coupling between bulk WS2 excitons and anapole modes in the WS2-Si nanodisk heterostructure array. By introducing anapole modes to confine light into subwavelength volumes and achieve large spatial overlapping between excitons and strong optical fields, efficient interaction between light and matter is achieved at the nanoscale.
PHOTONICS RESEARCH
(2022)
Article
Physics, Multidisciplinary
Chenjiang Qian, Viviana Villafane, Marko M. Petric, Pedro Soubelet, Andreas V. Stier, Jonathan J. Finley
Summary: We present resonant Raman spectroscopy of hBN-encapsulated MoS2 monolayer in a nanobeam cavity, revealing the mutual coupling of excitons, lattice phonons, and cavity vibrational phonons through temperature tuning. The enhancement of X0-induced Raman scattering and the suppression for X--induced are explained by the tripartite exciton-phonon-phonon coupling. Phononic hybridization between lattice and nanomechanical modes is found to play a key role in the excitonic photophysics and light-matter interaction in 2D-material nanophotonic systems.
PHYSICAL REVIEW LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Jie Jiang, Zhizhong Chen, Yang Hu, Yu Xiang, Lifu Zhang, Yiping Wang, Gwo-Ching Wang, Jian Shi
Summary: The flexo-photovoltaic effect induced by strain-gradient engineering enables the activation of bulk photovoltaic effect in centrosymmetric semiconductors, expanding material choices for future sensing and energy applications. The experimental demonstration in MoS2 reveals the potential for new optoelectronic phenomena in strain-gradient-engineered materials.
NATURE NANOTECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Yingjiao Zhai, Hui Yang, Sinan Zhang, Jinhua Li, Kaixi Shi, Fangjun Jin
Summary: A controllable material composed of Au nano-disk array and monolayer MoS2 was developed to improve the performance of SERS substrates. The composite showed enhanced Raman signal due to the thermal effect and internal quantum efficiency improvement of MoS2 caused by local surface plasmon resonance of Au. Through electromagnetic and chemical enhancements, the composite was utilized for highly sensitive SERS in detecting antibacterial residues in aquatic products, showcasing its potential for trace detection in food safety applications.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Baoyu Wang, Jr-Hau He, Bin Yu, Xin He, Fei Xue
Summary: The dynamic optical responses to external strains of 2D-3D hybrid heterostructures are rarely studied. In this work, we demonstrate the strain-tuned recombination dynamics of monolayer-MoS2 and thin-film-GaN heterostructures. The optical excitons in the heterostructures can be modulated by strains due to the MoS2 piezoelectric dipoles across the interfaces. The photoluminescence intensity of the heterostructures shows quenched responses with the increase in tensile strains, and the change in photoluminescence spectra strongly depends on the directions of the applied strains.
Article
Chemistry, Physical
Zhuoran Luo, Yunfei Xie, Ziwei Li, Yajuan Wang, Lihui Li, Ziyu Luo, Chenguang Zhu, Xin Yang, Ming Huang, Jianhua Huang, Delang Liang, Xiaoli Zhu, Dong Li, Anlian Pan
Summary: Optoelectronic synaptic elements based on transition metal dichalcogenides (TMDs) have limitations due to poor mobilities and weak light-matter interactions. However, by fabricating Au nanoparticle-coupled MoS2 heterostructures using chemical vapor deposition (CVD), enhanced light absorption and engineered plasmonic effects have been achieved, leading to optoelectronic devices with excellent synaptic behaviors and potential applications in neuromorphic electronics.
Article
Chemistry, Multidisciplinary
Wajid Ali, Ye Liu, Ming Huang, Yunfei Xie, Ziwei Li
Summary: This work systematically investigates the temperature-dependent Raman and photoluminescence (PL) characteristics of MoS2/WSe2 heterostructures. The results show that both the longitudinal and transverse modes of the heterostructure exhibit linear shifts towards low frequencies with increasing temperatures. The peak position and intensity of the PL spectra also show pronounced temperature dependency. The broadening of the Raman and PL peaks with increasing temperature can be attributed to phonon interaction and the expansion of the heterostructure's thermal coefficients.
Article
Chemistry, Multidisciplinary
Yi Wan, Xing Cheng, Yanfang Li, Yaqian Wang, Yongping Du, Yibin Zhao, Bo Peng, Lun Dai, Erjun Kan
Summary: Magneto-optical effects, originating from interactions between light and magnetism, provide a way to characterize magnetic materials and have applications in light modulators, magnetic field sensors, and data storage. Applying a perpendicular magnetic field can produce significant Raman scattering rotation in non-magnetic materials, offering the potential for manipulating inelastically scattered light.
Article
Nanoscience & Nanotechnology
Samar Ali Ghopry, Seyed M. Sadeghi, Yasmine Farhat, Cindy L. Berrie, Mohammed Alamri, Judy Z. Wu
Summary: This study demonstrates the rational design of intermixed WS2 and MoS2 nanodiscs on graphene for ultrasensitive SERS, surpassing the sensitivity limit of metallic plasmonic nanostructures-based SERS substrates. By enabling localized surface plasmonic resonance through dipole-dipole interactions, the enhanced Raman peak sensitivity is significantly increased, showcasing a promising approach for designing high-sensitivity SERS substrates entirely based on 2D atomic materials.
ACS APPLIED NANO MATERIALS
(2021)
Article
Chemistry, Physical
Yan Zhao, Liheng Zheng, Shiyi Han, Bo Xu, Zheyu Fang, Jin Zhang, Lianming Tong
Summary: This study reveals the abrupt enhancement of Raman scattered light at the edges of two-dimensional (2D) materials, which is closely related to the polarization of the incident light. The edge structure also modulates the polarization and selection rule of Raman scattered light.
Article
Nanoscience & Nanotechnology
J. Iwanski, P. Tatarczak, M. Tokarczyk, A. K. Dabrowska, J. Pawlowski, J. Binder, G. Kowalski, R. Stepniewski, A. Wysmolek
Summary: The recent progress in the growth of large-area boron nitride epilayers opens up new possibilities for future applications. However, it remains largely unclear how weakly attached two-dimensional BN layers interact with their substrate and how their properties are influenced by defects. In this work, the character of layer-substrate interaction for hBN layers grown by metal organic vapor phase epitaxy is investigated using Fourier-transform infrared spectroscopy. The results reveal strong differences in the interaction between as-grown and delaminated epitaxial layers, as well as a giant increase in the E (1u) phonon energy in a narrow temperature range.
Article
Physics, Applied
N. Zawadzka, T. Wozniak, M. Strawski, I. Antoniazzi, M. Grzeszczyk, K. Olkowska-Pucko, Z. Muhammad, J. Ibanez, W. Zhao, J. Jadczak, R. Stepniewski, A. Babinski, M. R. Molas
Summary: Photoluminescence from bulk HfS2 grown by the chemical vapor transport method is studied. A series of emission lines are observed at low temperature in the energy range of 1.4-1.5 eV. Intensity correlation analysis distinguishes two groups of observed excitonic transitions and their replicas involving acoustic and optical phonons. The emission is attributed to the recombination of excitons bound to iodine (I-2) molecules intercalated between layers of HfS2. The presence of I-2 molecules in the crystal is confirmed by secondary ion mass spectroscopy.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Johannes Binder, Aleksandra Krystyna Dabrowska, Mateusz Tokarczyk, Katarzyna Ludwiczak, Rafal Bozek, Grzegorz Kowalski, Roman Stepniewski, Andrzej Wysmolek
Summary: Hydrogen is a crucial component of green energy systems, and intense scientific efforts are needed in the field of materials science for this development. Two-dimensional crystals like hBN have shown promise as effective barriers for molecular hydrogen. However, it is uncertain if large-area hBN layers fabricated through industrial methods maintain these excellent properties. This study demonstrates that electron-beam-induced splitting of water creates hBN bubbles that can store molecular hydrogen for long periods, even under extreme mechanical deformation. Additionally, the epitaxial hBN allows for the direct visualization and monitoring of hydrogen generation through radiolysis of interfacial water, suggesting that hBN is not only a potential candidate for hydrogen storage but also for unconventional hydrogen production schemes.
Article
Materials Science, Multidisciplinary
Katarzyna Olkowska Pucko, Elena Blundo, Natalia Zawadzka, Salvatore Cianci, Diana Vaclavkova, Piotr Kapuscinski, Dipankar Jana, Giorgio Pettinari, Marco Felici, Karol Nogajewski, Miroslav Bartos, Kenji Watanabe, Takashi Taniguchi, Clement Faugeras, Marek Potemski, Adam Babinski, Antonio Polimeni, Maciej R. Molas
Summary: By studying the optical properties of WSSe monolayers, the existence of negatively charged excitons and single photon emitters in this material is discovered, providing opportunities for future quantum applications of S-TMDs.
Article
Chemistry, Multidisciplinary
M. Grzeszczyk, S. Acharya, D. Pashov, Z. Chen, K. Vaklinova, M. van Schilfgaarde, K. Watanabe, T. Taniguchi, K. S. Novoselov, M. I. Katsnelson, M. Koperski
Summary: It is discovered that despite similar structural and magnetic configurations, the coupling between excitons and magnetization is qualitatively different in CrBr3 and CrI3 films. Through a combination of optical spin pumping experiments and state-of-the-art theory, it is concluded that the hole-magnetization coupling has the opposite sign in CrBr3 and CrI3, as well as between the ground and excited exciton state. Efficient spin pumping capabilities are demonstrated in CrBr3 driven by magnetization via spin-dependent absorption, and the different origins of the magnetic hysteresis in CrBr3 and CrI3 are unraveled.
ADVANCED MATERIALS
(2023)
Article
Physics, Condensed Matter
Igor Antoniazzi, Natalia Zawadzka, Magdalena Grzeszczyk, Tomasz Wozniak, Jordi Ibanez, Zahir Muhammad, Weisheng Zhao, Maciej R. Molas, Adam Babinski
Summary: The temperature dependence of Raman scattering (RS) in bulk hafnium disulfide (HfS2) is investigated, revealing unexpected energy shifts of the main Raman-active modes at different temperatures, as well as the emergence of a new mode. The optical anisotropy of RS in HfS2 is highly dependent on the excitation energy, and the presence of iodine molecules intercalated in the van der Waals gaps between HfS2 layers is also analyzed for possible effects. The results are discussed in the context of resonant light-phonon interactions.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Arka Karmakar, Tomasz Kazimierczuk, Igor Antoniazzi, Mateusz Raczynski, Suji Park, Houk Jang, Takashi Taniguchi, Kenji Watanabe, Adam Babinski, Abdullah Al-Mahboob, Maciej R. Molas
Summary: Highlight absorption and strong photoluminescence in monolayer transition metal dichalcogenides make them ideal for optoelectronic device applications. Competing interlayer charge transfer and energy transfer processes control the photocarrier relaxation pathways in these TMD heterostructures. Our experiment shows efficient energy transfer between WSe2 and MoS2 in the heterostructure with hexagonal boron nitride, resulting in enhanced MoS2 photoluminescence.
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
Materials Science, Multidisciplinary
Lucja Kipczak, Artur O. Slobodeniuk, Tomasz Wozniak, Mukul Bhatnagar, Natalia Zawadzka, Katarzyna Olkowska-Pucko, Magdalena Grzeszczyk, Kenji Watanabe, Takashi Taniguchi, Adam Babinski, Maciej R. Molas
Summary: Excitons in thin layers of semiconducting transition metal dichalcogenides are highly affected by the modified electron-hole interaction, leading to deviations from the two-dimensional hydrogen atom model. In this study, we experimentally and theoretically investigate excitonic properties in ML and BL MoSe2 encapsulated in hexagonal BN. The magnetic field evolutions of the reflectance contrast spectra were measured, allowing the determination of g-factors for intralayer and interlayer excitons. First principles calculations were used to explain the dependence of g-factors on the number of layers and excitation state. Additionally, the ladder of excitonic s states in the ML could be reproduced using the k.p 2 BL.
Correction
Chemistry, Physical
Iaroslav Lutsyk, Karol Szalowski, Pawel Krukowski, Pawel Dabrowski, Maciej Rogala, Witold Kozlowski, Maxime Le Ster, Michal Piskorski, Dorota A. Kowalczyk, Wojciech Rys, Rafal Dunal, Aleksandra Nadolska, Klaudia Toczek, Przemyslaw Przybysz, Ewa Lacinska, Johannes Binder, Andrzej Wysmolek, Natalia Olszowska, Jacek J. Kolodziej, Martin Gmitra, Takuma Hattori, Yuji Kuwahara, Guang Bian, Tai-Chang Chiang, Pawel J. Kowalczyk
Article
Chemistry, Physical
Iaroslav Lutsyk, Karoli Szalowski, Pawel Krukowski, Pawel Dabrowski, Maciej Rogala, Witold Kozlowski, Maxime Le Ster, Michal Piskorski, Dorota A. Kowalczyk, Wojciech Rys, Rafal Dunal, Aleksandra Nadolska, Klaudia Toczek, Przemyslaw Przybysz, Ewa Lacinska, Johannes Binder, Andrzej Wysmolek, Natalia Olszowska, Jacek J. Kolodziej, Martin Gmitra, Takuma Hattori, Yuji Kuwahara, Guang Bian, Tai-Chang Chiang, Pawel J. Kowalczyk
Summary: The influence of intrinsic defects of 1T-TaS2 on charge density waves (CDWs) was investigated using scanning tunneling microscopy and spectroscopy (STM, STS), angle-resolved photoelectron spectroscopy (ARPES), and density functional theory (DFT). Various structural defects were identified, most of which had a local character limited to a single CDW site. However, one exception acted as a dopant, leading to band-bending and affecting multiple neighboring sites. While only one type of defect could be observed by STM topographic imaging, all defects were easily resolved in STS mapping. The modulation of the Mott band gap commensurate with the CDW and breaking of the three-fold symmetry of electronic states were observed. DFT calculations were used to investigate the electronic structure, focusing on sulfur vacancy and oxygen-sulfur substitution. The sulfur vacancy system showed metallic behavior and was identified as the origin of one of the experimentally observed defects. Moreover, the oxidation of 1T-TaS2 had different effects depending on the substitution site, resulting in electronic property heterogeneity.
Article
Chemistry, Multidisciplinary
K. P. Korona, J. Binder, A. K. Dabrowska, J. Iwanski, A. Reszka, T. Korona, M. Tokarczyk, R. Stepniewski, A. Wysmolek
Summary: Defects in semiconductors play a critical role in their functional properties, and understanding and controlling these defects is essential for their application. This study investigates the UV luminescence of intentionally introduced defects in hexagonal boron nitride grown by MOVPE. Photoluminescence and cathodoluminescence experiments revealed several characteristic lines, including X230, C300, and C380, corresponding to well-known and rarely observed defect bands. The study also found that the color center bands C were replaced by broad bands D in samples grown at high temperatures, indicating a different defect formation mechanism. Time-resolved photoluminescence analysis provided insight into the lifetimes and phonon interaction of the different defect lines.
Article
Chemistry, Multidisciplinary
Mehdi Arfaoui, Natalia Zawadzka, Sabrine Ayari, Zhaolong Chen, Kenji Watanabe, Takashi Taniguchi, Adam Babinski, Maciej Koperski, Sihem Jaziri, Maciej R. Molas
Summary: Investigated the optical properties of anisotropic excitons in GeS encapsulated by h-BN. Found that the exciton behavior is strongly influenced by the Coulomb interaction and exhibits polarization-dependent and anisotropic nature.