Article
Chemistry, Multidisciplinary
Xuewen Fu, Zepeng Sun, Shaozheng Ji, Fang Liu, Min Feng, Byung-Kuk Yoo, Yimei Zhu
Summary: In this study, surface plasmons on a silver film were excited using a femtosecond laser, and the subsequent transient dynamics were investigated using photon-induced near-field electron microscopy (PINEM). The results showed that unlike silver nanowires and nanorods, the PINEM intensity on the silver film did not show any polarization dependence, providing a simple method for identifying the time zero in 4D ultrafast electron microscopy (UEM).
Article
Chemistry, Multidisciplinary
Mingpeng Chen, Andrew C. Grieder, Tyler J. Smart, Kiley Mayford, Samuel McNair, Anica Pinongcos, Samuel Eisenberg, Frank Bridges, Yat Li, Yuan Ping
Summary: Hematite, a transition metal oxide, has the advantages of low cost, high abundance, and good chemical stability, making it a promising material for energy conversion and storage applications. However, its low carrier mobility and electrical conductivity have limited its widespread application. Atomic doping has been considered as a promising approach to improve its electrical conductivity, but the impact on carrier mobility at the atomic level has remained unclear. In this study, we used a kinetic Monte-Carlo sampling approach to calculate the electrical conductivity of doped hematite and investigated how different dopants affect carrier mobility. Our results showed that the local distortion of Fe-Fe pairs caused by dopants is closely related to the change in carrier mobility. Elements that minimize the distortion of Fe-Fe pairs are preferred for higher carrier mobility in hematite. The accuracy of our predictions was further validated by experimental measurements. This work provides practical guidelines for experimentalists on choosing dopants to optimize the electrical conductivity and performance of hematite-based devices.
Article
Chemistry, Physical
S. Aria Hosseini, Giuseppe Romano, P. Alex Greaney
Summary: The addition of porosity to thermoelectric materials can enhance the figure of merit ZT by reducing thermal conductivity, but also has detrimental effects on the power factor. By fine tuning carrier concentration and designing pore size and shape, electrical performance in nanoporous Si can be optimized. Cubic pores show the largest enhancement in Seebeck coefficient, with potential improvements of up to 60% at high carrier populations.
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Multidisciplinary Sciences
Hui-Min Wang, Xin-Bao Liu, Shi-Qi Hu, Da-Qiang Chen, Qing Chen, Cui Zhang, Meng-Xue Guan, Sheng Meng
Summary: Laser-controlled coherent phonon excitation significantly enhances carrier mobility by accelerating polaron transport. Selective excitation of specific phonon modes that overlap with the polaronic lattice deformation can reduce the energy barrier for polaron hopping. Nonadiabatic couplings between the electronic and ionic subsystems promote polaron migration through phonon-phonon scattering.
Article
Chemistry, Physical
Ondrej Dyck, Sinchul Yeom, Sarah Dillender, Andrew R. Lupini, Mina Yoon, Stephen Jesse
Summary: Graphene has unique properties such as ballistic transport, spin selectivity, quantum hall effect, etc., making it of great scientific interest. Nanopatterning and atomic scale modifications of graphene can further control its properties, including electronic properties and defect evolution.
Article
Chemistry, Multidisciplinary
Michael Yannai, Raphael Dahan, Alexey Gorlach, Yuval Adiv, Kangpeng Wang, Ivan Madan, Simone Gargiulo, Francesco Barantani, Eduardo J. C. Dias, Giovanni Maria Vanacore, Nicholas Rivera, Fabrizio Carbone, F. Javier Garcia de Abajo, Ido Kaminer
Summary: The ultrafast dynamics of charge carriers in solids is crucial for emerging optoelectronics, photonics, energy harvesting, and quantum technology applications. However, investigating and visualizing such nonequilibrium phenomena at nanometer-femtosecond scales has been a longstanding challenge. In this study, we propose and demonstrate a new interaction mechanism called charge dynamics electron microscopy (CDEM), which enables nanoscale imaging of the femtosecond dynamics of charge carriers in solids. By exploiting the strong interaction of free-electron pulses with terahertz (THz) near fields created by moving charges, we can directly retrieve the THz near-field amplitude and phase, reconstruct movies of the generated charges, and investigate previously inaccessible spatiotemporal regimes of charge dynamics in solids.
Article
Chemistry, Multidisciplinary
Kirill Kondratenko, David Guerin, Xavier Wallart, Stephane Lenfant, Dominique Vuillaume
Summary: This study investigates the electrical and thermal transport in thin films of a conducting polymer (PEDOT:OTf). The presence of highly conductive nano-domains is revealed by conductive atomic force microscopy (C-AFM). Thermal conductivity in the cross-plane direction is measured by null-point scanning thermal microscopy (NP-SThM). The results show a significant electronic contribution to the thermal transport.
Article
Nanoscience & Nanotechnology
Haili Ma, Sarka Mikmekova, Ivo Konvalina, Xiaozhe Yin, Fei Sun, Jakub Pinos, Nadezda Vaskovicova, Lukas Prucha, Ilona Mullerova, Eliska Materna Mikmekova, Deyang Chen
Summary: The precise control of ferroelectric and multiferroic domain states at the nanoscale is important for the development of low-energy-consumption nanoelectronic components. Scanning low-energy electron microscopy (SLEEM) was used for the first time to simultaneously acquire information on phase variants and ordered ferroelectric nanodomains in BiFeO3 nanoscale films. Electron trajectories simulation allowed for optimization and separation of morphological and polarization contrast in angle-selective backscattered electron imaging with a deceleration field.
ACS APPLIED NANO MATERIALS
(2021)
Article
Chemistry, Physical
Hua Su, Wei Wang
Summary: In situ optical imaging is a promising tool to study the structural complexities and heterogeneous activities of photofunctional materials. It can reveal the spatiotemporal heterogeneities of chemical reactivities at a single (sub)particle level and visually manipulate the photophysical and photochemical processes at the micro/nanoscale.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Maomao Zhang, Qiuxia Lu, Xiaojing Liu, Zhong An
Summary: In this study, the effects of intramolecular disorder on hot exciton dynamics in polymer solar cells are investigated. It is found that off-diagonal disorder has a more significant impact on hot exciton yield compared to diagonal disorder. Furthermore, the intensity of both disorder types has a nonmonotonic relationship with the relaxation time of hot excitons, indicating that intramolecular disorder can modulate the competition between hot exciton dissociation and internal conversion processes. This research provides guidance for enhancing charge generation in polymer solar cells dominated by hot exciton dissociation.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Anamika Barman, Surojit Halder, Shailendra K. Varshney, Gourab Dutta, Aniket Singha
Summary: A triple quantum dot system utilizing Coulomb coupling for nonlocal refrigeration is investigated, derived from the nonlocal thermodynamic engine proposed by Sanchez and Buttiker. Using the quantum master equation approach, it is shown that the maximum cooling power is limited and achieving a target reservoir temperature requires a voltage greater than a threshold voltage. As the target reservoir temperature decreases, the maximum cooling power and coefficient of performance deteriorate. This system combines fabrication simplicity with efficient cooling power for potential practical application in nonlocal cryogenic refrigeration systems.
Article
Chemistry, Multidisciplinary
Garth C. Egan, Edmond Y. Lau, Eric Schwegler
Summary: We directly imaged the laser-induced cavitation of micron and nanoscale bubbles using Movie-Mode Dynamic Transmission Electron Microscopy (MM-DTEM). The collapse of isolated nanobubbles was observed to occur in less than 50 ns, while larger bubbles (approximately 2-3 μm) grew and collapsed in less than 200 ns. Bubbles in close proximity to each other exhibited more complex behavior, with longer lifetimes and a higher likelihood of rebounding after collapse.
Article
Chemistry, Analytical
Olivier De Castro, Jean-Nicolas Audinot, Hung Quang Hoang, Cherif Coulbary, Olivier Bouton, Rachid Barrahma, Alexander Ost, Charlotte Stoffels, Chengge Jiao, Mikhail Dutka, Michal Geryk, Tom Wirtz
Summary: The article introduces the use of magnetic sector secondary ion mass spectrometry (SIMS) on a widely used instrument, focused ion beam (FIB)-scanning electron microscopy (SEM), for nanoscale investigations. It provides a detailed description of the instrument's layout and performance, as well as the research results obtained in various fields. The system demonstrates versatile capability for high-performance correlative studies in materials science and life sciences.
ANALYTICAL CHEMISTRY
(2022)
Article
Multidisciplinary Sciences
Nadezda Varkentina, Yves Auad, Steffi Y. Woo, Alberto Zobelli, Laura Bocher, Jean-Denis Blazit, Xiaoyan Li, Marcel Tence, Kenji Watanabe, Takashi Taniguchi, Odile Stephan, Mathieu Kociak, Luiz H. G. Tizei
Summary: Tracking the lifespan of optical excitations is crucial in understanding the photophysics of materials. In this study, electron spectroscopies were used to explore the creation and decay of excitations in two representative optical materials. The developed cathodoluminescence excitation spectroscopy method allows for imaging energy transfer pathways at the nanometer scale.
Article
Chemistry, Multidisciplinary
Matthew Ellis, Hui Yang, Samuele Giannini, Orestis G. Ziogos, Jochen Blumberger
Summary: The central challenge of organic semiconductor research is to develop cheap, disordered materials with high electrical conductivity. A novel computational methodology has been presented to address the poor fundamental understanding of the relationship between molecular packing structure and charge carrier mobility. Quantum dynamical simulations show a clear correlation between crystallinity, quantum delocalization, and charge carrier mobility, challenging the long-held belief of relatively localized charge carriers in disordered organic materials.
ADVANCED MATERIALS
(2021)
Article
Physics, Applied
Takuma Kobayashi, Maximilian Ruehl, Johannes Lehmeyer, Leonard K. S. Zimmermann, Michael Krieger, Heiko B. Weber
Summary: We studied the generation and transformation of intrinsic luminescent centers in 4H-polytype of silicon carbide through heavy ion implantation and subsequent annealing. Several unidentified luminescent features were observed and characterized under different temperatures and annealing conditions.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
Tobias A. de Jong, Tjerk Benschop, Xingchen Chen, Eugene E. Krasovskii, Michiel J. A. de Dood, Rudolf M. Tromp, Milan P. Allan, Sense Jan van der Molen
Summary: In twisted bilayer graphene, the moire pattern shows smaller spatial variation than previously reported. Thermal fluctuations and edge dislocations are observed, providing insights into the properties of twisted bilayer graphene.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Lipiao Bao, Baolin Zhao, Muhammad Ali, Mhamed Assebban, Bowen Yang, Malte Kohring, Dmitry Ryndyk, Thomas Heine, Heiko B. Weber, Marcus Halik, Frank Hauke, Andreas Hirsch
Summary: Structuring distinct building blocks on graphene opens opportunities for constructing 2D architectures and multifunctional devices. However, such structures are rare and existing examples are limited to small addends without easily accessible anchor points.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Multidisciplinary Sciences
Maria T. Schlecht, Matthias Knorr, Christoph P. Schmid, Stefan Malzer, Rupert Huber, Heiko B. Weber
Summary: This study investigated diodes under intense mid-infrared light-field pulses, providing the possibility of establishing light-field-driven electronics based on their characteristics.
Article
Materials Science, Multidisciplinary
E. Kodolitsch, V Sodan, M. Krieger, Heiko B. Weber, N. Tsavdaris
Summary: In this study, the impact of structural 4H-SiC epitaxial defects on the electrical characteristics and blocking capabilities of SiC power devices was investigated. The correlation between crystal defects and reduced blocking capability mechanism was determined, providing insights for improving the performance of SiC devices for high power applications.
MATERIALS RESEARCH EXPRESS
(2022)
Article
Engineering, Electrical & Electronic
Johannes A. F. Lehmeyer, Timon Citak, Heiko B. Weber, Michael Krieger
Summary: The performance of 4H silicon carbide (SiC) MOSFETs relies on the quality of the SiC/silicon oxide interface, which often has a high density of interface traps. To address this issue, a fast and reliable characterization method is introduced using machine-learning techniques. This method extracts accurate performance parameters, including a quantitative estimate of the interface trap density, from the transfer characteristics of 4H-SiC MOSFETs. It has been successfully validated against Hall-effect measurements and applied to different types of MOSFETs.
ELECTRONICS LETTERS
(2023)
Article
Physics, Applied
E. Kodolitsch, A. Kabakow, V Sodan, M. Krieger, H. Weber, N. Tsavdaris
Summary: In this study, a triangular epitaxial defect is identified as a nucleation source for the growth of recombination-induced bar shaped stacking faults (BSSFs) in forward-biased 4H-SiC p-n diode test structures. Basal plane dislocations that converted into threading screw dislocations, located close to the surface of the epitaxial layer and included in the triangular defect, act as the nucleation source for the BSSFs. These BSSFs expand from the top towards the bottom of the epitaxial layer, which is a newly reported expansion mechanism.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Christian Dolle, Victor Oestreicher, Alberto M. Ruiz, Malte Kohring, Francisco Garnes-Portoles, Mingjian Wu, Gabriel Sanchez-Santolino, Alvaro Seijas-Da Silva, Marta Alcaraz, Yolita M. Eggeler, Erdmann Spiecker, Josep Canet-Ferrer, Antonio Leyva-Perez, Heiko B. Weber, Maria Varela, Jose J. Baldovi, Gonzalo Abellan
Summary: In this study, a few-layers bismuth hybrid material of electronic grade structural quality was synthesized using an unprecedented colloidal photocatalyzed, one-pot redox reaction. The material exhibited a sulfur-alkyl-functionalized reconstructed surface that prevented oxidation and resulted in a tuned electronic structure. The metallic behavior of the hybrid material was supported by ab initio predictions and room temperature transport measurements.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Tobias A. de Jong, Luuk Visser, Johannes Jobst, Ruud M. Tromp, Sense Jan van der Molen
Summary: Terrace-sized, single-orientation graphene can be grown on silicon carbide by thermal decomposition, but exhibits significant variation in electron transport properties. The moire pattern formed by lattice mismatch between the graphene and buffer layer leads to domain boundaries and edge dislocations. The coexistence of anisotropic stripe domains and isotropic trigonal domains causes intrinsic disorder in epitaxial graphene, and the growth process and substrate influence the domain orientation.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Xingchen Chen, Mio Poortvliet, Sense Jan van der Molen, Michiel J. A. de Dood
Summary: Researchers have successfully controlled the type of junction by stacking 2H-NbSe2 flakes and found that the shape of interference patterns is not only determined by the type of junction, but also by the magnetic field orientation and interface geometry.
Article
Materials Science, Multidisciplinary
Peter S. Neu, Makars Siskins, Eugene E. Krasovskii, Rudolf M. Tromp, Sense Jan van der Molen
Summary: In van der Waals (vdW) materials, the electron mean free path (MFP) is influenced by discrete states in the unoccupied band structure. However, measurements on vdW materials lack energy resolution except for graphene. In this study, reflection and transmission spectra of freestanding few-layered molybdenum disulfide (MoS2) samples were obtained, revealing enhanced electron transmissivity states above the vacuum level. A quantum-mechanical calculation confirmed an understanding of elastic scattering in MoS2, and a model was developed to extract the inelastic MFP spectrum.
Article
Materials Science, Multidisciplinary
Tobias A. de Jong, Xingchen Chen, Johannes Jobst, Eugene E. Krasovskii, Ruud M. Tromp, Sense Jan Molen
Summary: Stacking domain boundaries in Van der Waals heterostacks exhibit different contrast in BF-LEEM depending on their depth and size, with amplitude contrast being dominant for shallow boundaries between the top two graphene layers and phase contrast being strong for small domains. We derive a general rule-of-thumb for the expected BF-LEEM contrast of domain boundaries in Van der Waals materials.
Proceedings Paper
Computer Science, Hardware & Architecture
Lena Bergmann, Gregor Pobegen, Daniel Schlogl, Holger Schulze, Heiko B. Weber, Michael Krieger
Summary: A new, simplified and versatile current transient spectroscopy (CTS) measurement setup is demonstrated in this study. The depth profile of the PtH defect in fully processed silicon HV test diodes is investigated using this setup. It is found that a proton field stop (FS) at the backside of the test devices can effectively reduce the PtH defect concentration throughout the diode volume, and a strong correlation between the depth profile of the PtH defect and the leakage current is observed.
2022 IEEE 34TH INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES AND ICS (ISPSD)
(2022)
