Article
Chemistry, Physical
Chao Hou, Jingwen Deng, Jianxin Guan, Qirong Yang, Zhihao Yu, Yilin Lu, Zihan Xu, Zefan Yao, Junrong Zheng
Summary: The research reveals that laser irradiation can enhance the photoluminescence of monolayer MoS2, with different effects observed under different atmospheres, being more significant in the presence of oxygen. Additionally, physically adsorbed water also plays a role in enhancing the photoluminescence of monolayer MoS2.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Ram Kumar, Aditya H. Kelkar, Rahul Singhal, Vasant G. Sathe, Ram Janay Choudhary, Neeraj Shukla
Summary: We studied the effects of 1.5 MeV proton ion irradiation on thin MoS2 flakes. XRD analysis revealed a shift in the crystalline phase and the presence of defects and strain in the irradiated samples. XPS analysis confirmed the absence of impurities and transition metal elements, and further confirmed the presence of sulfur vacancies in the irradiated sample. Raman spectroscopy showed a red shift in the vibrational modes, indicating the presence of tensile strain. The observed ferromagnetism is attributed to locally aligned magnetic dipole moments induced by sulfur vacancies and strain caused by proton beam irradiation.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Ajit Kumar Dash, Hariharan Swaminathan, Ethan Berger, Mainak Mondal, Touko Lehenkari, Pushp Raj Prasad, Kenji Watanabe, Takashi Taniguchi, Hannu-Pekka Komsa, Akshay Singh
Summary: Control of defect spatial location and density in two-dimensional materials is achieved through electron beam irradiation. We found evidence of defect creation in monolayer MoS2 at ultralow accelerating voltages (? 5 kV), despite the absence of expected defect formation during surface morphology measurements. By studying the evolution of E' and A(1)' Raman modes and the appearance of defect-activated peaks, we confirm the formation of defects. Simulated Raman spectra of MoS2 with realistic defect distributions match experimental results, with sulphur vacancies identified as suggested defects. Studies involving control samples decouple defects, doping, and carbonaceous contamination. Cryogenic photoluminescence quenching and the presence of defect peaks are observed, while carbonaceous contamination does not affect defect formation. These findings have implications in the fields of photonics and quantum emitters.
Article
Engineering, Chemical
Kehui Xue, Lianqing Yu, Huihua Luo, Xiaomeng Ji, Xiang Li, Haifeng Zhu, Yaping Zhang
Summary: Phase control and defect engineering were used to fabricate metallic 1T-phase molybdenum disulfide quantum dots (1T-MoS2 QDs) decorated 2D g-C3Nx nanosheets (1T-MoS2 QDs@g-C3Nx) for efficient photocatalytic hydrogen evolution reaction (HER). The introduction of nitrogen defects and the presence of MoS2 QDs improved the charge carrier transport and reaction dynamics, leading to superior H2 production performance. The resulting 1T-MoS2 QDs@g-C3Nx exhibited a high and stable cycling and durability under continuous visible light irradiation.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Wonbong Choi, Junyoung Kim, Eunho Lee, Gayatri Mehta, Vish Prasad
Summary: The study demonstrates that meticulous defect engineering can significantly enhance the piezoelectric effect of large-scale sputtered, asymmetric 2D MoS2, resulting in outstanding piezoelectric performance and excellent stability. The sulfur vacancy density is positively correlated with the piezoelectric strength, which increases with the annealing temperature.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Jing Li, Shike Hu, Shuang Wang, He Kang, Zhiying Chen, Sunwen Zhao, Yanhui Zhang, Yanping Sui, Guanghui Yu
Summary: The study reports the degradation of MoS2 grown by CVD in atmospheric environment, showing that moisture accelerates oxidation of MoS2. Isolating oxygen and moisture is beneficial for improving the long-term stability of TMDCs.
Article
Chemistry, Multidisciplinary
Yolanda Manzanares-Negro, Guillermo Lopez-Polin, Kazunori Fujisawa, Tianyi Zhang, Fu Zhang, Ethan Kahn, Nestor Perea-Lopez, Mauricio Terrones, Julio Gomez-Herrero, Cristina Gomez-Navarro
Summary: The study demonstrates that introducing atomic vacancies in MoS2 monolayers can effectively prevent catastrophic failure and increase the material's fracture toughness.
Article
Chemistry, Multidisciplinary
Ke Xu, Ting Liang, Zhisen Zhang, Xuezheng Cao, Meng Han, Ning Wei, Jianyang Wu
Summary: The study explores the critical role of misorientation angle in thermal transport characteristics across 5|7 polar dislocation-dominated GBs in monolayer MoS2. Results show a U-shaped thermal conductance with varying misorientation angle, influenced by GB energy, 5|7 dislocation type, and grain size. This unique thermal transport phenomenon is primarily attributed to rising phonon-boundary softening and scattering, as well as an increase in localized phonon modes at GBs.
Article
Chemistry, Physical
Samuel J. Brooke, Mark R. Waterland
Summary: We report resonantly enhanced defect modes in the Raman spectrum of molybdenum disulfide (MoS2), which are similar to the D mode in graphene. These modes become active at edges under indirect resonance conditions and can be used for sensitive defect quantification and differentiation of edge structures. The technique also allows characterization of the structure-dependent properties of MoS2 nanomaterials and provides insights into the low energy landscape of the conduction band.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Kory Burns, Anne Marie Z. Tan, Jordan A. A. Hachtel, Anikeya Aditya, Nitish Baradwaj, Ankit Mishra, Thomas Linker, Aiichiro Nakano, Rajiv Kalia, Eric J. J. Lang, Ryan Schoell, Richard G. G. Hennig, Khalid Hattar, Assel Aitkaliyeva
Summary: Ultrathin MoS2 shows remarkable characteristics at the atomic scale and is resistant to weak external stimuli. Ion beam modification can selectively adjust the size, concentration, and morphology of defects in 2D materials. By combining experiments, calculations, simulations, and transfer learning, this study demonstrates that irradiation-induced defects can create a rotation-dependent moire pattern and surface acoustic waves in vertically stacked homobilayers of MoS2. The direct correlation between stress and lattice disorder is also demonstrated. This research sheds light on the engineering of defects to tailor the angular mismatch in van der Waals solids.
Article
Chemistry, Multidisciplinary
Sebastian Calderon, Rafael V. Ferreira, Deepyanti Taneja, Jayanth T. Raghavendrarao, Langyan Zhou, Ricardo M. Ribeiro, Deji Akinwande, Paulo J. Ferreira
Summary: This study used scanning transmission electron microscopy images and computer simulations to map the atomic electrostatic fields of MoS2 monolayers, revealing the impact of sulfur monovacancies and divacancies on the electric field and total charge distribution. The results showed a significant redistribution of the electric field in regions containing defects, with a decrease in field strength as sulfur atoms are removed and a polarity inversion in total charge distribution due to the absence of sulfur atoms.
Article
Chemistry, Multidisciplinary
Harikrishnan Ravichandran, Theresia Knobloch, Andrew Pannone, Alexander Karl, Bernhard Stampfer, Dominic Waldhoer, Yikai Zheng, Najam U. Sakib, Muhtasim Ul Karim Sadaf, Rahul Pendurthi, Riccardo Torsi, Joshua A. A. Robinson, Tibor Grasser, Saptarshi Das
Summary: This study provides a comprehensive insight into the defect dynamics observed in monolayer MoS2 FETs at varying gate biases and temperatures. The measured source-to-drain currents exhibit random telegraph signals (RTS) due to charge transfer between the semiconducting channel and individual defects. Oxygen vacancies or aluminum interstitials are identified as probable defect candidates based on temperature and gate bias dependence. The study reveals local current crowding effects and rich defect dynamics, including anomalous RTS and giant RTS, in monolayer MoS2 FETs.
Article
Chemistry, Physical
Wenwen Wang, Hao Zhao, Hong Liu, Lu Wang, Youyong Li
Summary: In this study, the mechanical behavior and fracture resistance of MoS2 bilayers with grain boundaries (GBs) were investigated using first-principles calculations. The results showed that the MoS2 bilayers with GBs exhibited anisotropic mechanical properties, with better strength in the zigzag direction compared to the armchair direction. Additionally, GBs containing 8-membered rings showed higher fracture resistance than those containing 4-membered rings.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Engineering, Electrical & Electronic
Jun Zhang, Zixian Lian, Pengfei Hou
Summary: 2-D material-based photodetectors have great potential for various applications due to their unique properties. This article explores the use of electron irradiation engineering to improve the photo detection performance of MoS2-based phototransistors. The effectiveness of this engineering depends on the specific irradiation strategy employed.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2023)
Article
Physics, Applied
Bo Liu, Ying Chen, Chao Ma, Ying Jiang, Danliang Zhang, Zheyuan Xu, Ziyu Luo, Huawei Liu, Junyu Qu, Xin Yang, Yushuang Zhang, Dong Li, Weihao Zheng, Biyuan Zheng, Shula Chen, Anlian Pan
Summary: Two-dimensional transition metal dichalcogenides have attracted significant attention due to their unique photo-physics and excellent optoelectronic properties. However, the presence of defects greatly affects their optoelectronic properties. Researchers have developed a defect repair strategy using gallium doping, which significantly enhances the photoluminescence of monolayer molybdenum disulfide.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Kimmo Mustonen, Christoph Hofer, Peter Kotrusz, Alexander Markevich, Martin Hulman, Clemens Mangler, Toma Susi, Timothy J. Pennycook, Karol Hricovini, Christine Richter, Jannik C. Meyer, Jani Kotakoski, Viera Skakalova
Summary: Researchers have successfully stabilized a 2D structure composed of copper and iodine at room temperature by using graphene oxide as the template material, providing a new method for producing more exotic phases of materials for experiments.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Alberto Trentino, Kenichiro Mizohata, Georg Zagler, Manuel Laengle, Kimmo Mustonen, Toma Susi, Jani Kotakoski, E. Harriet Ahlgren
Summary: This study demonstrates an efficient method to implant individual gold atoms into graphene, with the ability to control the concentration of gold atoms introduced. Covalently bound gold atoms in graphene can withstand high-intensity electron irradiation during microscopy experiments.
Article
Materials Science, Multidisciplinary
Georg Zagler, Maximilian Stecher, Alberto Trentino, Fabian Kraft, Cong Su, Andreas Postl, Manuel Laengle, Christian Pesenhofer, Clemens Mangler, E. Harriet Ahlgren, Alexander Markevich, Alex Zettl, Jani Kotakoski, Toma Susi, Kimmo Mustonen
Summary: Substituting heteroatoms into graphene can tune its properties for various applications. Recent discovery shows that covalent impurities in graphene can be manipulated at atomic precision. This study reports the vacancy-mediated substitution of aluminium into laser-cleaned graphene and investigates their dynamics under electron irradiation. The results show good agreement with predictions and reveal interesting findings.
Article
Chemistry, Physical
Andreas Postl, Pit Pascal Patrick Hilgert, Alexander Markevich, Jacob Madsen, Kimmo Mustonen, Jani Kotakoski, Toma Susi
Summary: We estimated the migration barrier of carbon adatoms on freestanding monolayer graphene to be (0.33 ± 0.03) eV by quantifying its temperature-dependent electron knock-on damage.
Article
Nanoscience & Nanotechnology
Kelotchi S. Figueroa, Natalya A. Zimbovskaya, Nicholas J. Pinto, Chengyu Wen, A. T. Charlie Johnson
Summary: Charge transport in graphene far from the Dirac point under ferroelectric gating was studied. Non-monotonic/monotonic/non-monotonic behavior in conductivity was observed. The gate polarization compensated impurity charges and reduced charge scattering. The non-monotonic response in conductivity reappeared far from the Dirac point due to phonon scattering.
Article
Physics, Multidisciplinary
Anna Niggas, Janine Schwestka, Karsten Balzer, David Weichselbaum, Niclas Schluenzen, Rene Heller, Sascha Creutzburg, Heena Inani, Mukesh Tripathi, Carsten Speckmann, Niall McEvoy, Toma Susi, Jani Kotakoski, Ziyang Gan, Antony George, Andrey Turchanin, Michael Bonitz, Friedrich Aumayr, Richard A. Wilhelm
Summary: We compared the ion-induced electron emission from freestanding monolayers of graphene and MoS2 and found that graphene emitted six times more electrons, despite both materials having similar work functions. This can be explained by a charge-up in MoS2 that prevents low energy electrons from escaping the surface within a few femtoseconds after ion impact.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
E. Harriet Ahlgren, Alexander Markevich, Sophie Scharinger, Bernhard Fickl, Georg Zagler, Felix Herterich, Niall McEvoy, Clemens Mangler, Jani Kotakoski
Summary: Oxidation is the main cause of degradation in 2D materials, especially transition metal dichalcogenides (TMDs). This study investigates the chemical effects of oxygen on single-layer MoS2 and MoTe2 under controlled low-pressure oxygen environments using in situ electron microscopy. It is found that MoTe2 is reactive to oxygen and undergoes significant degradation, while MoS2 is inert. Additionally, hydrocarbon contamination accelerates the degradation rate of TMDs. The findings provide important insights into the oxygen-related deterioration of 2D materials.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Rajendra Singh, Daniel Scheinecker, Ursula Ludacka, Jani Kotakoski
Summary: Graphene, the best known 2D material, is prone to corrugations. Factors such as the size of the free-standing area, preparation method, surface contamination, and electron-beam-induced disorder affect the corrugation in graphene.
Article
Nanoscience & Nanotechnology
Kenan Elibol, Toma Susi, Clemens Mangler, Dominik Eder, Jannik C. Meyer, Jani Kotakoski, Richard G. Hobbs, Peter A. van Aken, Bernhard C. Bayer
Summary: The presence of metal atoms at the edges of graphene nanoribbons (GNRs) allows for tailoring their physical properties. In this study, indium (In) chains were formed on the edges of graphene-supported GNRs through laser heating and physical vapor deposition. Aberration-corrected scanning transmission electron microscopy (STEM) revealed that multiple In atoms preferred to decorate the edges of the GNRs. Electron-beam irradiation induced the migration of In atoms along the edges and the formation of longer chains. Theoretical calculations confirmed the metallic character of these structures. This research provides insights into the formation and properties of long linear metal atom chains at graphitic edges.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Analytical
Vidia A. Gokool, Janet Crespo-Cajigas, Amritha Mallikarjun, Amanda Collins, Sarah A. Kane, Victoria Plymouth, Elizabeth Nguyen, Benjamin S. Abella, Howard K. Holness, Kenneth G. Furton, Alan T. Charlie Johnson, Cynthia M. Otto
Summary: In this study, the performance of trained detection dogs and a noninvasive analytical instrumentation method were compared in identifying COVID-19 positive individuals. The results showed that dogs performed better than the computational model when faced with non-ideal samples.
Article
Multidisciplinary Sciences
Qicheng Zhang, Li He, Eugene J. Mele, Bo Zhen, A. T. Charlie Johnson
Summary: Integrated phononics plays a crucial role in fundamental physics and technology. This study investigates the use of piezomagnetic materials to break time-reversal symmetry and achieve topological phases and non-reciprocal devices. The authors develop a theoretical framework that combines linear elasticity with Maxwell's equations and demonstrate the existence of phononic Chern insulators based on piezomagnetism.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Erick Arguello Cruz, Pedro Ducos, Zhaoli Gao, Alan T. Charlie Johnson, Dario Niebieskikwiat
Summary: In this study, the effect of ferromagnetic nickel nanoparticles on the magnetotransport properties of chemical-vapor-deposited graphene was characterized. It was found that these nanoparticles greatly suppressed the zero-field peak of resistivity caused by weak localization and enhanced the high-field magnetoresistance. The interaction between the graphene and the nickel nanoparticles was attributed to a local exchange coupling, which did not affect the intrinsic transport parameters of graphene, indicating that the changes in magnetotransport properties were purely magnetic in origin.
Article
Nanoscience & Nanotechnology
Nishal Shah, Vasant Iyer, Zhiping Zhang, Zhaoli Gao, Juhwan Park, Venkata Yelleswarapu, Firooz Aflatouni, A. T. Charlie Johnson, David Issadore
Summary: We developed CMOS-compatible graphene Hall sensors integrated with PDMS microfluidics for magnetic sensing in blood, which can overcome the limitations of traditional technologies in clinical applications, and show high sensitivity and reliability. They can also be integrated with microfluidics and sensing electronics for in-flow detection of magnetic beads.
MICROSYSTEMS & NANOENGINEERING
(2023)
Article
Nanoscience & Nanotechnology
Anis Chiout, Cleophanie Brochard-Richard, Laetitia Marty, Nedjma Bendiab, Meng-Qiang Zhao, A. T. Charlie Johnson, Fabrice Oehler, Abdelkarim Ouerghi, Julien Chaste
Summary: A study has found that the frequency of nanomechanical resonators can be effectively tuned at the nanoscale using a suspended MoS2 membrane heated by the Joule effect, with a significantly larger modulation amplitude compared to other approaches. This research is crucial for fully harnessing the potential of two-dimensional materials.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Alexandru Chirita, Alexander Markevich, Mukesh Tripathi, Nicholas A. Pike, Matthieu J. Verstraete, Jani Kotakoski, Toma Susi
Summary: This study presents a comprehensive three-dimensional first-principles theory of knock-on displacements in materials, describing the dynamics of irradiation-induced damage. The model is validated using precise measurements of knock-on damage in graphene, and is applied to study reversible jumps of pyridinic nitrogen atoms. The results indicate stronger inelastic effects at defects compared to pristine graphene.
