Article
Materials Science, Multidisciplinary
Yuki Nagai
Summary: A numerical study reveals the presence of vortex pinning in a superconducting quasicrystal without impurities and defects, attributed to the lack of translational symmetry leading to intrinsic inhomogeneity in the superconducting order parameter. Experimental detection of atomic-scale inhomogeneous superconducting order parameter in quasicrystals influenced by vortex pinning effects is proposed.
Article
Chemistry, Multidisciplinary
Mianli Huang, Jiafeng Lian, Ruiru Si, Lingling Wang, Xiaoyang Pan, Ping Liu
Summary: Spatial separation of electrons and holes is critical for improving photocatalytic performance. In this study, a ZnO-Au-MnOx heterogeneous nanostructure photocatalyst was prepared by photodepositing Au and MnOx on ZnO crystal facets. The ZnO-Au-MnOx exhibited higher photocatalytic activity than ZnO and ZnO-Au, attributed to efficient photoinduced carrier separation.
Article
Chemistry, Multidisciplinary
Mianli Huang, Jiafeng Lian, Ruiru Si, Lingling Wang, Xiaoyang Pan, Ping Liu
Summary: Spatial separation of electrons and holes is crucial for improving photocatalytic performance. In this study, a ZnO-Au-MnOx heterogeneous nanostructure photocatalyst was prepared by selectively depositing Au and MnOx on different crystal facets. The efficient photoinduced carrier separation of ZnO-Au-MnOx resulted in enhanced photocatalytic performance.
Article
Engineering, Electrical & Electronic
Ewelina Zdanowicz, Artur P. Herman, Marta Sobanska, Zbigniew R. Zytkiewicz, Wojciech Olszewski, Detlef Hommel, Robert Kudrawiec
Summary: Combining mature technology like GaN with emerging materials is an important path in applied science research. In this study, the vulnerability of surface barriers on temperature for Ga-polar GaN surface was investigated for the first time using spectroscopy. The results showed that the density of GaN surface states exhibited a strong temperature dependence.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Christopher J. Clymore, Subhajit Mohanty, Zhe (Ashley) Jian, Athith Krishna, Stacia Keller, Elaheh Ahmadi
Summary: The study indicates that well-behaved CV profiles can be achieved by depositing HfO2 directly on GaN or SiN dielectric, while deposition of HfO2 on the AlGaN cap layer results in Fermi level pinning.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2021)
Article
Optics
Ying-Yen Liao
Summary: In this study, the dynamic entanglement between two molecules in a polar-molecule array under static electric fields is investigated. The research focuses on the evolution of entanglement under the influence of intrinsic decoherence, the stability of entanglement between arbitrary molecules in the array, and the induction of high end-to-end concurrence through state transfer. The study demonstrates the fragile and robust behavior of entanglement under different initial states, and reveals the cyclic peaks of concurrence corresponding to different Bell-like states during the state transfer processes.
Article
Physics, Applied
Jochen Bruckbauer, Yipin Gong, Ling Jiu, Michael J. Wallace, Anja Ipsen, Sebastian Bauer, Raphael Muller, Jie Bai, Klaus Thonke, Tao Wang, Carol Trager-Cowan, Robert W. Martin
Summary: The study found that using stripe structures during overgrowth of non-polar GaN can significantly reduce extended defects and improve emission uniformity. Additionally, the combination of stripes and microrods provides a promising approach for defect reduction and emission uniformity in non-polar GaN.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Baodan Liu, Zongyi Ma, Cai Zhang, Yonghui Ma, Liu Yang, Wenjin Yang, Jing Li, Xinglai Zhang
Summary: This study discusses the simultaneous nucleation and growth of horizontal nonpolar nanowires and vertical polar nanorods on GaN substrate, emphasizing the importance of the initial premature nucleus for this process. Microstructure analysis and cathodoluminescence characterization confirm the crystalline nature and single-peak luminescence emission in the visible range of the nanostructures.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Construction & Building Technology
Frederico G. P. Moreira, Lucas E. C. Silva, Victor I. M. dos Santos
Summary: The Brazilian housing program "Minha Casa, Minha Vida" aims to address the housing deficit issue by distributing contracted housing units. The findings of this study suggest that there is a positive relationship between urban housing deficit and contracted housing units from a temporal perspective, but a negative relationship from a spatial perspective, indicating heterogeneity among states.
Article
Physics, Applied
Hirohisa Hirai, Yoshinao Miura, Akira Nakajima, Shinsuke Harada, Hiroshi Yamaguchi
Summary: The flatband voltage (V-fb) on m-face trenches was found to be significantly higher compared to a-face trenches, and the variation in V-fb among different trench directions was suppressed after treating trench sidewalls with a TMAH solution. This indicates that the origin of V-fb variation is attributed to the GaN crystal face dependence of fixed charge density at SiO2/GaN interfaces.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Ryota Ochi, Takuya Togashi, Yoshito Osawa, Fumimasa Horikiri, Hajime Fujikura, Kazunari Fujikawa, Takashi Furuya, Ryota Isono, Masamichi Akazawa, Taketomo Sato
Summary: To investigate the influence of the near-surface region on the electrical properties of AlGaN/GaN HEMTs, transmission line method and X-ray photoelectron spectroscopy (XPS) measurements were conducted on three samples. One sample exhibited poor ohmic properties. XPS results showed that the surface-Fermi-level (E FS) position of the poor-ohmic sample was deeper than others. Removal of a 5 nm thick surface layer through contactless photo-electrochemical etching resulted in a shift of E FS to the same position as the other samples, improving the contact resistance.
APPLIED PHYSICS EXPRESS
(2023)
Article
Chemistry, Physical
Alexey Yu Aladyshkin, Anna S. Aladyshkina, Sergey Bozhko
Summary: This study experimentally investigates the local electronic properties of quasi-two-dimensional Pb(111) islands with different types of screw dislocations on their surfaces. The findings show that screw dislocations and hidden dislocation lines affect the local electronic properties by connecting or generating independent hidden lines, leading to non-quantized variation in the local thickness of the Pb terraces.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Applied
Zhenjiang Li, Kesheng Gao, Ying Han, Shiqi Ding, Yanglansen Cui, Minmin Hu, Jian Zhao, Meng Zhang, Alan Meng, Jimmy Yun, Zhiming Liu, Da-Wei Wang, Changlong Sun
Summary: Electronic engineering of GaN is enhanced by Cu cation substitution, which improves electrode performance for Li ion storage. The Cu-GaN electrode exhibits high capacity and stability, attributed to impurity electronic states and efficient electron migration introduced by Cu substitution. This research provides insights for advanced energy storage applications.
JOURNAL OF ENERGY CHEMISTRY
(2022)
Article
Physics, Applied
Li Zhang
Summary: This study deduced and analyzed the polar optical phonon modes of a wurtzite nitride triangular quantum dot using the dielectric continuum model. The exact and analytical phonon states of exact confined modes were derived, and it was found that the frequency of these modes in the nitride triangular quantum dot systems could take both the longitudinal optical phonons in the z-direction and in the xy-plane. The spatial distribution and electron-phonon coupling strength of these modes were discussed, showing that their potential is strictly confined within the triangular quantum dot ranges.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2022)
Article
Physics, Multidisciplinary
Chung-Jong Bong, Chang Wan Ahn, Sung-Bum Bae, Eun Kyu Kim
Summary: The study showed that using GaN substrates can significantly improve the structural properties of GaN epitaxial structures and enhance their quality. Four traps were identified through optical conductance deep level transient spectroscopy analysis, with H4 and H1 possibly related to gallium and nitrogen vacancies.
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Paolo Rosi, Alexander Clausen, Dieter Weber, Amir H. Tavabi, Stefano Frabboni, Peter Tiemeijer, Rafal E. Dunin-Borkowski, Enzo Rotunno, Vincenzo Grillo
Summary: This article reports on the automatic alignment of a transmission electron microscope with an orbital angular momentum sorter using a convolutional neural network. The neural network can control all relevant parameters of the microscope and the sorter to optimize spectral resolution, compensating for mechanical and optical misalignments. The alignment process is completed over a few frames and can be kept stable using the fast fitting time of the neural network.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Materials Science, Multidisciplinary
Ping-Luen Ho, Zhihao Huang, Lei Jin, Si-Young Choi, Rafal E. Dunin-Borkowski, Joachim Mayer, Shik Chi Edman Tsang, Xiaoyan Zhong
Summary: Aberration-corrected analytical transmission electron microscopy (TEM) is used to determine the atomic-scale cation order in a nanosized Sr3Fe2ReO9 phase, revealing tripled-layered repeats of Fe and Re cations along [111](pc) and an ordering vector of 1/3[111]*. Density functional theory calculations based on a relaxed theoretical model consistent with the experimental images determine the magnetic ground states and exchange parameters of the newly discovered Sr3Fe2ReO9 phase, where nearest-neighbour Fe and Re cations are coupled antiferromagnetically.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Materials Science, Multidisciplinary
Michael Oberaigner, Alexander Clausen, Dieter Weber, Gerald Kothleitner, Rafal E. Dunin-Borkowski, Daniel Knez
Summary: Position averaged convergent beam electron diffraction (PACBED) is a convenient and precise technique for determining thickness in a scanning transmission electron microscope. The method can be automated using convolutional neural networks (CNNs) to enhance speed and ease of application, but simulation and training can be computationally expensive. To simplify the process, a server-based database of pretrained CNN models accessed through a web service is proposed. A working prototype with a shared CNN database for three material systems demonstrates the usability of the method, allowing microscope operators to determine specimen thickness quickly and reproducibly during a session, without prior knowledge of machine learning or multislice modeling. The service can also be integrated into other software and workflows through the API.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Materials Science, Multidisciplinary
Marc Heggen, Michael Feuerbacher, Rafal E. Dunin-Borkowski
Summary: Metadislocations, novel defects in complex metallic alloys, have been observed on the atomic scale in the T-Al-Mn-Fe phase using in-situ high-resolution transmission electron microscopy. Their motion is characterized by discrete jumps between low-energy configurations and a mixed glide/climb process.
MATERIALS RESEARCH LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Andras Kovacs, Nithin B. Venkataraman, Varun Chaudhary, Sriswaroop Dasari, Thibaud Denneulin, R. V. Ramanujan, Rajarshi Banerjee, Rafal E. Dunin-Borkowski
Summary: The microstructural features significantly affect the coercivity of magnetic alloys. While the influence of homophase boundaries on magnetic domain wall pinning is well understood, the role of heterophase interfaces on domain wall motion is complex and not well known. This study used advanced electron microscopy techniques to reveal the dramatic changes in the magnetization reversal process in an Al0.3CoFeNi magnetic complex concentrated alloy (CCA) and its impact on coercivity. The heterophase FCC/BCC interfaces were found to have a stronger effect on coercivity compared to isostructural chemically ordered/disordered interfaces, providing valuable insights for the rational design of microstructure in magnetic alloys.
Article
Chemistry, Physical
Maurice Vennewald, Nina Michelle Sackers, Andree Iemhoff, Isabella Kappel, Claudia Weidenthaler, Ansgar Meise, Marc Heggen, Rafal E. Dunin-Borkowski, Luke Keenan, Regina Palkovits
Summary: Single-atoms on carbon-nitrogen supports are considered catalysts for various reactions, but it's uncertain if these species or subnanometer clusters formed during reactions are the active species. This study investigates the behavior of palladium single-atoms on graphitic carbon nitride during ethylene hydrogenation and H2-D2 exchange. The results suggest that palladium aggregates to clusters at 100 degrees C in the presence of ethylene and hydrogen, and these clusters are the active species in catalytic reactions. This research highlights the importance of analyzing the dynamics of catalysts during reactions to identify the active species and understand the influence of gas atmosphere on metal speciation.
JOURNAL OF CATALYSIS
(2023)
Article
Chemistry, Physical
Kun Zhang, Qiang Guo, Yehong Wang, Pengfei Cao, Jian Zhang, Marc Heggen, Joachim Mayer, Rafal E. Dunin-Borkowski, Feng Wang
Summary: In this work, selective ethylene carbonylation to 3-pentanone was achieved using in situ produced hydrogen via a water-gas shift (WGS) reaction on a defective ceria-supported Rh catalyst. The interface of Rh/CeO2 activates water, CO, and ethylene, facilitating the WGS reaction and ethylene carbonylation. A redox pathway for the WGS reaction was proposed based on in situ FTIR results, and water was confirmed as the hydrogen source for ethylene carbonylation through mass spectrometry (MS) study.
Article
Nanoscience & Nanotechnology
Enzo Rotunno, Simone Gargiulo, Giovanni M. Vanacore, Chen Mechel, Amir H. Tavabi, Rafal E. Dunin-Borkowski, Fabrizio Carbone, Ivan Madan, Stefano Frabboni, Tugrul Guner, Ebrahim Karimi, Ido Kaminer, Vincenzo Grillo
Summary: Entanglement and correlation play a crucial role in quantum mechanics and have been successfully applied in optics for ghost imaging. In this study, we propose a similar scheme in electron microscopy, which exploits the correlation between electrons and collective mode excitations in a sample. This concept allows us to form an image of the sample on an electron camera without direct illumination, enabling high-resolution imaging beyond the wavelength of collective modes.
Article
Engineering, Electrical & Electronic
D. S. Rosenzweig, M. Schnedler, R. E. Dunin-Borkowski, Ph. Ebert, H. Eisele
Summary: Hydrogen exposure and annealing at 400 degrees C cause layer-by-layer etching of n-doped GaAs(110) surface, leading to the formation of step edge sections with [001] normal vector. It also results in the formation of negatively charged point defects, causing Fermi level pinning in the lower part of the bandgap. The desorption of adatoms is primarily attributed to hydrogen bonding and subsequent Ga-H desorption, while the electronic properties of the initially grown nanowires cannot be revealed from the hydrogen-cleaned surface.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Chemistry, Multidisciplinary
Yue Zhang, J. Paul van Schayck, Adriain Pedrazo-Tardajos, Nathalie Claes, Willem E. M. Noteborn, Peng-Han Lu, Hans Duimel, Rafal E. Dunin-Borkowski, Sara Bals, Peter J. Peters, Raimond B. G. Ravelli
Summary: Cryogenic electron microscopy can produce high-resolution reconstructions of macromolecules in ice, but the electron beam can cause motion and distortion. Sample charging is a contributing factor, which can be alleviated by using a conductive film. In this study, a layer of graphene was used to mitigate sample charging, resulting in high-resolution reconstructions and reduced particle movement. This approach may have broad implications for various electron microscopy techniques and the study of radiation damage.
Article
Chemistry, Inorganic & Nuclear
Georgia Gkouzia, Damian Guenzing, Ruiwen Xie, Teresa Wessels, Andraas Kovacs, Alpha T. N'Diaye, Maïrton Major, J. P. Palakkal, Rafal E. Dunin-Borkowski, Heiko Wende, Hongbin Zhang, Katharina Ollefs, Lambert Alff
Summary: This study investigates the effect of copper substitution on the magnetic properties of SmCo5 thin films synthesized by molecular beam epitaxy. The results show that copper substitution not only stabilizes the formation of the SmCo5 structure but also enhances magnetic anisotropy and coercivity. X-ray magnetic circular dichroism and scanning transmission electron microscopy reveal the nanoscale inhomogeneities in the distribution of copper and cobalt.
INORGANIC CHEMISTRY
(2023)
Article
Microscopy
David Landers, Ian Clancy, Rafal E. Dunin-Borkowski, Dieter Weber, Andrew Stewart
Summary: This paper introduces the free and open-source software TEMGYM Advanced, which calculates the electron beam trajectory in an electron microscope using ray tracing methods. It validates the accuracy of aberration coefficient calculations and demonstrates parallelised electron ray tracing through magnetic components. TEMGYM Advanced is a valuable resource for the electron microscopy community and complements the growing ecosystem of free and open-source software in this field.
Article
Microscopy
Jean Felix Dushimineza, Janghyun Jo, Rafal E. Dunin-Borkowski, Knut Mueller-Caspary
Summary: Stray electric fields generated by biased gold needles in free space were analyzed through finite-element simulations, scanning TEM, and electron holography experiments. Numerical solutions of the electrostatic potential and electric field were obtained for different needle geometries. An analytical model based on line charges provided a qualitative understanding that differed from the simulations. Experimental measurements using scanning TEM and electron holography initially showed a discrepancy of about 60%. However, the discrepancy was resolved by including the long-range potential landscape from the simulations into the reference wave in electron holography.
Article
Multidisciplinary Sciences
Deli Kong, Andras Kovacs, Michalis Charilaou, Fengshan Zheng, Lihua Wang, Xiaodong Han, Rafal E. Dunin-Borkowski
Summary: In this study, nanoscale observations were conducted to investigate how tensile strain modifies magnetic domains in a ferromagnetic Ni thin plate. Formation and dissociation of strain-induced periodic 180° magnetic domain walls perpendicular to the strain axis were observed. The magnetization transformation showed stress-determined directional sensitivity and was reversible and tunable through the size of the nanostructure. This work provides direct evidence for magnetoelasticity and allows quantifiable local measurements of strain-induced changes in the magnetic states of nanomaterials.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
Shengbo You, Peng-Han Lu, Thomas Schachinger, Andras Kovacs, Rafal E. Dunin-Borkowski, Andrew M. Maiden
Summary: Electron ptychography has the ability to recover high contrast and ultra-high resolution images. It can also quantitatively map phase variations resulting from magnetic and electric fields over extended fields of view.
APPLIED PHYSICS LETTERS
(2023)
