Article
Chemistry, Multidisciplinary
E. E. Hernandez-Vazquez, S. Lopez-Moreno, F. Munoz, J. L. Ricardo-Chavez, J. L. Moran-Lopez
Summary: Theoretical study on the adsorption of Mn trimer on Au(111) and Cu(111) surfaces was conducted. The lowest energy configuration for the trimer on both metals was found to be the AF(Delta) configuration, forming an isosceles triangle.
Article
Chemistry, Physical
D. A. Olyanich, T. Utas, L. Bondarenko, A. Y. Tupchaya, D. Gruznev, A. N. Mihalyuk, A. Zotov, A. A. Saranin
Summary: The study investigates the changes in the structural and electronic properties of the quasi-one-dimensional metal-chain Au/Si(111)5 x 2 reconstruction induced by Bi adsorption. Bi atoms substitute Au atoms in the edge rows, leading to increased electronic heterogeneity. Bi adsorption increases the system Fermi energy, providing a way to tune the metallic properties of the system through controlled Bi dosing.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Juan M. Lombardi, Doris Grumelli, Rico Gutzler, H. Fabio Busnengo, Paula Abufager
Summary: We used density functional theory (DFT) calculations to analyze the properties of FeTPyP self-assembled monolayers (SAMs) and FeTPyP+Fec metal-organic coordination networks (MOCNs) on Au(111). The relative importance of multiple competing interactions that determine the optimum structure and stability of both networks was determined through a rigorous step-by-step approach. In the FeTPyP/Au(111) SAMs, we observed a complex energy landscape, with molecules preferring molecule-molecule distances around 13.7 and 14.3 angstrom. Molecule-surface interactions were more prominent in less dense packing (around 14.3 angstrom), while intermolecular interactions favored the compact structure (around 13.7 angstrom). In the FeTPyP-Fec/Au(111) MOCN, the strong Fec-Npy bond between the peripheral iron atom Fec and nitrogen atoms of neighboring pyridyl groups (Npy) was found to drive the network development, with the preferred molecule-molecule distance remaining at around 13.7 angstrom. These findings highlight the necessity of theoretical treatments that consider all relevant interactions to adequately describe surface-supported SAMs and MOCNs.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Robert Bavisotto, Nicholas Hopper, Alejandro Boscoboinik, Quintus Owen, Wilfred T. Tysoe
Summary: Electron and X-ray diffraction, electron microscopy, and reflection-absorption infrared spectroscopy are used to study the structures of thin organic films on metal substrates. The chemical nature and molecular conformations of the film can be determined from the vibrational frequencies, and the film orientation can be obtained using infrared selection rules. The study on furfural adsorbed on gold and palladium substrates shows that the substrate reactivity influences the film structure, with changes in the furfural film's conformation and order observed with variations in film thickness and temperature.
Article
Materials Science, Multidisciplinary
Xingzhi Pang, Jianbing Yang, Anmin Li, Mingjun Pang, Yue Xiao, Hang Nong, Haiqinq Qin, Chengyu Liu
Summary: This study investigated the atomic structures and electronic properties of NbC(111)/Cu (111) interfaces using first-principles calculations. Eight possible interface models were studied, and the most stable configuration was identified as the C-hcp-Cu interfacial structure. Electronic structure analysis revealed that the major interfacial bonds were Cu-Nb covalent bond and Cu-C covalent bond at the Nb-terminal and C-terminal interfaces, respectively.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Juan C. Moreno Hernandez, Rodrigo Ponce-Perez, Gregorio Hernandez Cocoletzi, Do Minh Hoat, Noboru Takeuchi
Summary: In this study, spin-polarized first-principles calculations were performed to investigate the electronic and magnetic properties of the CrN (111) surface. The results showed that the stability of the surfaces varied under different environmental conditions, and demonstrated how to manipulate surface properties for spintronic applications.
SURFACES AND INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Xingzhi Pang, Loujiang Yang, Jianbing Yang, Mingjun Pang, Zhengbing Xu, Anmin Li, Bingly Wei, Hongqun Tang
Summary: Using first-principles calculations, the adsorption and diffusion mechanisms of Si and Zr atoms on the L12 Al3Ti (111) surface have been studied. The most favorable adsorption sites for Si and Zr atoms are H4 and Ti, respectively. The covalent Ti-Si bonds in the Si@Al3Ti(111) system are from the hybridization of Si 3p and Ti 3d orbitals, while the Ti-Zr ionic bond in the Zr@Al3Ti(111) system comes from the contribution of Ti 3d and Zr orbitals. Formation energy calculations show that Si and Zr atoms prefer to incorporate into the Al site of the first layer and the Ti site of the second layer, respectively. The energy barriers for Si and Zr atom diffusion on or into the Al3Ti (111) surface are also evaluated.
Article
Chemistry, Physical
Ling Fu, Longbin Yan, Long Lin, Kun Xie, Linghao Zhu, Chaozheng He, Zhanying Zhang
Summary: The study investigates the catalytic potential of Fe-embedded Au (111) monolayer for N2 fixation, demonstrating its ability to activate inert N2 molecules and identifying the limiting step of the N2 reduction reaction.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Xingzhi Pang, Xiyu Yang, Jianbing Yang, Yanjun Zhao, Mingjun Pang
Summary: The interface structure, interfacial stability, and wettability of ZrC(111)/ diamond(111) interfaces were systematically investigated using first-principles calculations. It was found that the C-termination ZrC(111) surface occupying the bridge of diamond (111) surface is the most stable and favorable structure among six different models, based on calculated results of adhesion work and interface energy.
DIAMOND AND RELATED MATERIALS
(2021)
Article
Physics, Multidisciplinary
Lin Hu, Bing Huang, Feng Liu
Summary: The 7 x 7 reconstruction of the Si(111) surface, discovered sixty years ago, remains unclear in terms of its atomistic formation mechanism. By developing an artificial neural-network potential of DFT quality, researchers were able to accurately simulate the formation process, revealing a step-mediated atom-pop rate-limiting process that leads to the complex reconstruction.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Umamahesh Thupakula, Priya Laha, Gertjan Lippertz, Koen Schouteden, Asteriona-Maria Netsou, Aleksandr Seliverstov, Herman Terryn, Lino M. C. Pereira, Chris Van Haesendonck
Summary: Two-dimensional allotropes of tellurium, known as tellurene, have recently attracted attention in materials research due to their exotic properties in ultrathin form. This study reports the observation of three different 2D superstructures of tellurene on Au(111) surfaces using an alternative experimental deposition approach. The superstructures were characterized using scanning tunneling microscopy and spectroscopy, Auger electron spectroscopy, and field emission AES. The study found that the formation of these superstructures led to changes in the surface reconstruction of Au(111), and the electronic properties of the tellurium atoms showed a strong dependence on their structural arrangement. The emergence of band gaps with a p-type charge character was observed in two of the superstructures on Au(111).
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
A. H. M. Abdul Wasey, G. P. Das
Summary: Metal/semiconductor heterojunctions play a key role in materials physics and electronic device applications. This study investigates the structure-property relationships at the interface of transition metal disilicides/silicon using first principles density functional theory. Different surface barrier heights and the evolution of metal-induced gap states are observed for different types of interfaces, providing important insights for silicon-based device applications.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Chemistry, Physical
Tahereh Mohammadi Hafshejani, Jonas Wohlgemuth, Peter Thissen
Summary: Strain affects the surface reactivity of H-Si(111) by weakening Si-H bonds and causing intensity fluctuations in bending modes, leading to the formation of a new peak associated with the diffusion of hydrogen atoms. The findings suggest that both back bonds and up bonds are easily oxidized under strain, with the direct formation of Si-OH without an energy barrier. Different oxidation pathways predominate when strain is present.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Denghui Ma, Zexing Cao
Summary: The research showed that unsaturated Cu sites have strong adsorption ability towards the nerve agent sarin, and the decomposition of GB on the surface mainly proceeds through the fission of the P-F bond. Compared to the CuO(111) surface, the Cu2O(111) surface has a stronger binding interaction with GB and can effectively degrade GB under mild conditions.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Shijie Sun, Baijin Li, Boyu Fu, Zilin Ruan, Hui Zhang, Wei Xiong, Yong Zhang, Gefei Niu, Jianchen Lu, Xiaoqing Zuo, Lei Gao, Jinming Cai
Summary: Nanoscale low-dimensional chiral architectures have attracted increasing scientific interest due to their potential applications in chiral recognition, separation, and transformation. In this study, large-area two-dimensional chiral networks on Au(111) and one-dimensional metal-liganded chiral chains on Cu(111) were successfully constructed and characterized. The chiral transformation of the chiral networks on Au(111) was analyzed, and the electronic state information was studied using scanning tunneling spectroscopy. The combination of scanning tunneling microscopy and non-contact atomic force microscopy techniques enabled ultra-high-resolution characterization of chiral structures on low-dimensional surfaces.
CHINESE CHEMICAL LETTERS
(2022)
Article
Multidisciplinary Sciences
Elham M. T. Fadaly, Alain Dijkstra, Jens Rene Suckert, Dorian Ziss, Marvin A. J. van Tilburg, Chenyang Mao, Yizhen Ren, Victor T. van Lange, Ksenia Korzun, Sebastian Kolling, Marcel A. Verheijen, David Busse, Claudia Roedl, Juergen Furthmueller, Friedhelm Bechstedt, Julian Stangl, Jonathan J. Finley, Silvana Botti, Jos E. M. Haverkort, Erik P. A. M. Bakkers
Article
Materials Science, Multidisciplinary
Jens Rene Suckert, Claudia Roedl, Juergen Furthmueller, Friedhelm Bechstedt, Silvana Botti
Summary: The study shows that band inversion in hexagonal germanium can be achieved through strain, transitioning from a pseudo-direct band gap to a direct band gap, with moderate tensile uniaxial strain showing the potential to achieve this goal.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Physics, Condensed Matter
Filipe Matusalem, Friedhelm Bechstedt, Ivan Guilhon, Marcelo Marques, Lara K. Teles
Summary: A computationally efficient methodology for calculating Z(2) topological invariants is presented and applied to group-IV graphene-like systems, showing the importance of quasiparticle (QP) effects in predicting the topological or trivial character.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Jakob Genser, Daniele Nazzari, Viktoria Ritter, Ole Bethge, Kenji Watanabe, Takashi Taniguchi, Emmerich Bertagnolli, Friedhelm Bechstedt, Alois Lugstein
Summary: Silicene shows promising potential for high-performance devices due to its unique electronic and optical properties, but its outstanding characteristics are not preserved on certain growth templates.
Article
Materials Science, Multidisciplinary
Abderrezak Belabbes, Friedhelm Bechstedt, Silvana Botti
Summary: By conducting ab initio calculations, it has been demonstrated that perturbed hexagonal germanium is an excellent material for active optoelectronic devices in the infrared region. Perturbing the system through atomic substitution and applying strain can greatly enhance the oscillator strength and energy transition of the material, making it suitable for light emitting devices.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Pedro Borlido, Jens Rene Suckert, Juergen Furthmueller, Friedhelm Bechstedt, Silvana Botti, Claudia Roedl
Summary: Ab initio calculations were performed to study the electronic and optical properties of hexagonal SiGe alloys. It was found that alloying can enhance the optical transitions of hexagonal Ge, making the alloys efficient optical emitters for integrated optoelectronic applications.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Pedro Borlido, Friedhelm Bechstedt, Silvana Botti, Claudia Roedl
Summary: Ge-rich hexagonal SiGe alloys have emerged as new direct-gap semiconductors with potential for integration of photonics on silicon. Optical, transport, and thermoelectric properties of these alloys were investigated using first-principles methods. The alloy band gap remains direct below 45% Si content and optical spectra show tunability with composition. Transport coefficients exhibit similar behaviors in cubic and hexagonal alloys, but the latter display anisotropic response due to reduced symmetry. The Seffbeck coefficients and thermoelectric power factors show nonmonotonous variations with Si content regardless of temperature.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Mousa Bejani, Olivia Pulci, Naser Karimi, Elena Cannuccia, Friedhelm Bechstedt
Summary: In this study, we conducted a detailed analysis of the electronic properties and lattice dynamics of different layers of beta-InSe through theoretical calculations. We found that the few-layers systems are indirect band gap semiconductors with a Mexican-hat-shaped top valence band. The phonon analysis revealed the dynamical stability of mono- and bi-layers, as well as the breakdown of the longitudinal-optical-transverse-optical splitting with an increase to four layers. The Raman and IR spectra were dominated by in-plane and out-of-plane lattice vibrations, and small shifts of the peak positions and variations of the peak intensities were observed as signatures of the number of layers.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Multidisciplinary Sciences
Giancarlo Cappellini, Juergen Furthmueller, Friedhelm Bechstedt, Silvana Botti
Summary: We conducted a systematic investigation on the electronic and optical properties of two crystals of alkaline earth metal fluorides using state-of-the-art techniques. The calculations were performed using density functional theory, many-body perturbation theory, and the Bethe-Salpeter equation. Our results showed distinctive properties for rutile MgF2 compared to cubic SrF2 and other members of the alkaline earth metal fluoride family. The excitonic effects in finite-sized systems were confirmed through a comparison between bulk and cluster calculations.
Article
Materials Science, Multidisciplinary
Martin Keller, Abderrezak Belabbes, Juergen Furthmueller, Friedhelm Bechstedt, Silvana Botti
Summary: In this paper, the energetic, structural, elastic, and electronic properties of hexagonal SiGe are analyzed using density functional theory. The phase diagram shows that the diamond structure is the most stable, but hexagonal modifications are close to the phase boundary. Band structure calculations predict significant changes in electronic states with hexagonality. Si is always a semiconductor with indirect band gaps, while the hexagonal Ge polytypes have direct band gaps. Band alignment based on the branch-point energy leads to type-I heterocrystalline interfaces between Ge polytypes.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Alessia Muroni, Simone Brozzesi, Friedhelm Bechstedt, Paola Gori, Olivia Pulci
Summary: We conducted a comprehensive study on the structural and electronic properties of a graphene/phosphorene heterostructure using density functional theory. We found that by optimizing the lattice constants, the in-plane strain of the heterostructure can be reduced to under 1%. The presence of weak van der Waals interaction between the graphene and phosphorene layers was confirmed. Additionally, we demonstrated that G/P heterostructures can form both n-type and p-type Schottky contacts under external perturbations, suggesting their potential for novel electronics applications and optoelectronic devices.
Article
Materials Science, Multidisciplinary
Abderrezak Belabbes, Silvana Botti, Friedhelm Bechstedt
Summary: This study investigates the natural and true band profiles at heterojunctions formed by hexagonal SixGe1-x alloys. The findings show that the natural band offsets are not significantly affected by different alignment methods or functional choices. Ge-rich alloys exhibit a type-I heterocharacter with direct band gaps, while Si-rich junctions are type-I but with an indirect band gap. The true band lineups at pseudomorphically grown heterostructures are strongly influenced by the biaxial strain generated in the adjacent alloys.
Proceedings Paper
Engineering, Electrical & Electronic
E. M. T. Fadaly, A. Dijkstra, J. R. Suckert, D. Ziss, M. A. J. Tilburg, C. Mao, Y. Ren, V. T. V. Lange, S. Koling, M. A. Verheijen, D. Busse, C. Rodl, J. Furthmuller, F. Bechstedt, J. Stangl, J. J. Finley, S. Botti, J. E. M. Haverkort, E. P. A. M. Bakkers
Summary: The study found that a direct band gap can be created in Si1-xGex alloys by changing the crystal structure from cubic to hexagonal, offering new possibilities for the application of opto-electronic devices.
2021 SILICON NANOELECTRONICS WORKSHOP (SNW)
(2021)
Article
Materials Science, Multidisciplinary
Friedhelm Bechstedt, Simone Grillo, Olivia Pulci, Paola Gori
Summary: The thermal properties and electrical conductance of 2D electron gases in doped Xenes were studied using a four-band model, taking into account spin-orbit interactions and the influence of an electric field. The results showed that the thermal conductance of Xenes increases linearly or quadratically with temperature, with only small variations in electrical conductance, except for plumbene. In addition, for 2D electron gases with nearly Dirac character, the ratio of electron thermal conductance to electric conductance depends on doping level and temperature.
Article
Materials Science, Multidisciplinary
Kaori Seino, Atsushi Oshiyama
