Article
Chemistry, Physical
Alexey Rodin, Ainur Khairullin
Summary: The peculiarities of Ni and Fe diffusion in polycrystalline Cu and Cu-Fe alloys at a temperature range of 650-750 degrees C were studied. The obtained values of the Ni GB diffusion triple product were an order of magnitude less than the values obtained by the radiotracer method. The significant supersaturation of the Cu-based solid solution near the Fe/Cu interface was confirmed as a peculiarity of Fe diffusion.
Article
Materials Science, Multidisciplinary
Qi Chen, Rong Hu, Shenbao Jin, Fei Xue, Gang Sha
Summary: This study investigated the irradiation-induced segregation of solutes at typical grain boundaries in Fe-Mn-Si steel, revealing that Mn and C segregate at grain boundaries and the extent of segregation depends on the characteristics of the boundaries, with the strongest segregation observed at random high-angle boundaries.
Article
Materials Science, Multidisciplinary
Eszter Bodnar, Viktor Takats, Tamas Fodor, Jozsef Hakl, Yuri Kaganovskii, Guang Yang, Xiaogang Yao, Kalman Vad
Summary: This study investigates the grain boundary diffusion of Si in polycrystalline Cu film, revealing the appearance of Si atoms on the copper surface and the depth distribution of Si in Cu grain boundaries. The surface morphology of Cu films and the formation of chemical bonds were analyzed. The diffusion coefficients were estimated and the surface segregation factor was determined, along with the formation of Cu-O-Si atomic bonds on the Cu film surface.
Review
Materials Science, Ceramics
Hidehiro Yoshida
Summary: This paper briefly summarizes recent research on high-temperature mass transport phenomena through grain boundaries in oxide ceramics. Two techniques for controlling grain boundary mass transport in oxide ceramics have been proposed: changing the chemical composition in the grain boundary, and applying an external electric field or current to the material. The former technique improves the sinterability and high-temperature plastic deformability of oxide ceramics through grain boundary segregation of doped cations. The latter technique significantly enhances diffusional mass transport through grain boundaries, and an athermal effect, in addition to the Joule heating effect, seems to exist.
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN
(2022)
Review
Chemistry, Multidisciplinary
Zheng Gao, Chongqian Leng, Hongquan Zhao, Xingzhan Wei, Haofei Shi, Zeyun Xiao
Summary: This review provides an overview of the electrical properties of grain boundaries in polycrystalline optoelectronic materials and discusses the factors influencing the electrical behaviors of grain boundaries. It also explores how modifying the electrical behaviors of grain boundaries can enhance the performance of optoelectronic devices.
ADVANCED MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Joseph Messina, Renjie Luo, Ke Xu, Guanghong Lu, Huiqiu Deng, Mark A. Tschopp, Fei Gao
Summary: Magnesium alloys have advantages in applications due to their high strength-to-weight ratio, but properties like corrosion resistance, formability, and creep are still concerns, especially in magnesium-aluminum alloys. This study quantifies aluminum segregation energetics at grain boundaries using atomistic simulations, showing that the segregation of aluminum is influenced by grain boundary structure and the local atomic environment, which has broad implications for grain boundary science and engineering.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Ceramics
Jingjing Sun, Yu-Wei You, Xuebang Wu, Hong-Yue Song, B. S. Li, C. S. Liu, Vladimir Krsjak
Summary: In SiC ceramics, helium tends to aggregate at grain boundaries, but the interaction mechanisms between helium and grain boundaries are still unclear. In this study, first-principles calculations show that helium easily segregates at grain boundaries with open structures and low charge density, and these grain boundaries significantly enhance helium diffusion.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Yu Liu, Mariano Calcabrini, Yuan Yu, Seungho Lee, Cheng Chang, Jeremy David, Tanmoy Ghosh, Maria Chiara Spadaro, Chenyang Xie, Oana Cojocaru-Miredin, Jordi Arbiol, Maria Ibanez
Summary: This study optimizes the thermoelectric performance of polycrystalline SnSe by surface engineering and consolidating solution-processed SnSe particles. The resulting SnSe-CdSe nanocomposites exhibit high thermoelectric figures of merit due to the presence of CdSe nanoparticles and a large number of defects.
Article
Materials Science, Multidisciplinary
Han Lin Mai, Xiang-Yuan Cui, Daniel Scheiber, Lorenz Romaner, Simon P. Ringer
Summary: This study investigates the segregation, co-segregation, and cohesion effects of various transition metals in ferritic-iron grain boundaries. The results demonstrate that different grain boundary characters affect not only the segregation behavior of transition metals, but also their effects on cohesion. The study also introduces a novel quantitative method for assessing the effects of segregated elements on interfacial cohesion and reveals significant variations in solute-solute interactions at grain boundaries compared to the bulk.
Article
Materials Science, Multidisciplinary
Ting Luo, Federico Serrano-Sanchez, Hanna Bishara, Siyuan Zhang, Ruben Bueno Villoro, Jimmy Jiahong Kuo, Claudia Felser, Christina Scheu, G. Jeffrey Snyder, James P. Best, Gerhard Dehm, Yuan Yu, Dierk Raabe, Chenguang Fu, Baptiste Gault
Summary: The study investigates the correlation between microstructure and electrical conductivity of n-type NbCo1-xPtx Sn half-Heusler alloys, finding that Pt at grain boundaries locally reduces resistivity. The increase in grain size after annealing leads to improved electrical conductivity.
Article
Nanoscience & Nanotechnology
Megan J. McCarthy, Timothy J. Rupert
Summary: This study investigates the migration behavior of a faceted Sigma 11 boundary in Cu doped with Ag atoms, revealing that solute atoms segregate to a facet with more free volume and greatly reduce boundary velocity in one migration direction. However, a directionally-dependent motion mechanism can escape solute pinning and speed up migration in the other direction, uncovering a new mechanism of chemically-induced anisotropy in grain boundary mobility.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Multidisciplinary
Elida I. de Obaldia, Jesus J. Alcantar-Pena, Frederick P. Wittel, Jean Francois Veyan, Salvador Gallardo-Hernadez, Yury Koudriavtsev, Dainet Berman-Mendoza, Orlando Auciello
Summary: This paper investigates the effect of hydrogen atom insertion into the grain boundaries of polycrystalline diamond films, focusing on the H atom concentration and its impact on the properties. The study suggests a simple model where two dangling bonds per unit cell of C atoms serve as the site of hydrogen incorporation. The experiment results show that the concentration of H atoms at the grain boundaries is consistent regardless of grain size. Conductive atomic force microscopy and ultraviolet photoelectron spectroscopy techniques were used to observe the electrical behavior and metallic properties of the films.
APPLIED SCIENCES-BASEL
(2021)
Article
Materials Science, Multidisciplinary
Pulkit Garg, Zhiliang Pan, Vladyslav Turlo, Timothy J. Rupert
Summary: Interfacial segregation and subsequent complexion transitions in polycrystalline Cu-Zr alloys were studied using hybrid Monte Carlo/molecular dynamics simulations. It was found that at moderate temperature, grain boundary segregation is the dominant behavior, with heterogeneous segregation within the boundary network. Changes in physical parameters correlated with dopant concentration. At higher temperature, a significant fraction of originally ordered boundaries transitioned to amorphous complexions, demonstrating the coexistence of different complexion types.
Article
Materials Science, Multidisciplinary
C. J. Marvel, K. D. Behler, J. C. LaSalvia, R. A. Haber, M. P. Harmer
Summary: This study investigates the potential of grain boundary complexion engineering to improve fracture resistance of boron-based ceramics. It reveals the presence of silicon segregation at grain boundaries and quantifies the changes in grain boundary energy due to silicon segregation, leading to improvements in fracture resistance.
Article
Chemistry, Physical
Thomas Defferriere, Dino Klotz, Juan Carlos Gonzalez-Rosillo, Jennifer L. M. Rupp, Harry L. Tuller
Summary: The study shows that grain boundary resistance in solid ionic conductors can be decreased by illuminating with above-bandgap light. Experimental results demonstrate the increase in grain boundary conductance of a 3 mol% Gd-doped ceria thin film by approximately 3.5 times at 250 degrees C, with the reduction of activation energy from 1.12 to 0.68 eV under illumination. The discovered opto-ionic effect could potentially contribute to the development of new electrochemical storage and conversion technologies, as well as fast and contactless control or diagnosis of ionic conduction in polycrystalline solids.
Article
Materials Science, Coatings & Films
Ribhu Sharma, Minghan Xian, Chaker Fares, Mark E. Law, Marko Tadjer, Karl D. Hobart, Fan Ren, Stephen J. Pearton
Summary: Schottky rectifiers fabricated on beta-Ga2O3 have high breakdown voltage and low on-state resistance, making them suitable for power inverters. Utilizing a multiprobe array can mitigate the impact of current spreading on measurements, enabling the measurement of high forward currents.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Materials Science, Coatings & Films
Ribhu Sharma, Minghan Xian, Mark E. Law, Marko Tadjer, Fan Ren, Stephen J. Pearton
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2020)
Article
Engineering, Electrical & Electronic
Nimesh Pokhrel, Thomas A. Weingartner, Miguel A. Sulangi, Erin E. Patrick, Mark E. Law
Summary: This study investigates the influence of process variations on grain formation by modeling the propagation of a seed layer with different crystal orientations. The study focuses on grain boundary formation and the influence of grain structure on device performance.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Engineering, Manufacturing
Thomas A. Weingartner, Chiao-Han Kuo, Andrew Thomas, Scott E. Thompson, Mark E. Law
Summary: Some packaging technologies for electronic devices introduce compressive biaxial stress and variable vertical stress, leading to increased variability in key device parameters. Reducing package-induced compressive stress, or introducing tensile stress, can improve device variability due to local stress variations.
IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Thomas Weingartner, Nimesh Pokhrel, Miguel Sulangi, Lars Bjorndal, Erin Patrick, Mark E. Law
Summary: The development of a process/device simulation platform for modeling superconductor electronics integrates process and device simulation tools to simulate Josephson junction fabrication processes and predict operational figures of merit. This aims to provide an environment for simulating JJ circuits.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Physics, Applied
Miguel Antonio Sulangi, Laetitia Bettmann, T. A. Weingartner, N. Pokhrel, E. Patrick, M. Law, A. Kreisel, P. J. Hirschfeld
Summary: This study explores the effect of grain boundaries on the critical current of a Josephson junction and finds that the presence of grain boundaries can lead to significant drops in critical current, particularly when a tunnel barrier is present. The disorder associated with grain boundaries causes substantial variations in critical currents, which has implications for superconducting electronics applications.
JOURNAL OF APPLIED PHYSICS
(2021)
Review
Materials Science, Coatings & Films
Ribhu Sharma, Mark E. Law, Fan Ren, Alexander Y. Polyakov, Stephen J. Pearton
Summary: The understanding of dopant and impurity diffusion in gallium oxide is still in its early stages, with high diffusion coefficients of impurities like H and F impacting electrical conductivity. Nitrogen annealing suppresses diffusion and loss of dopants, retaining a higher initial dose compared to oxygen annealing.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Materials Science, Coatings & Films
Xinyi Xia, Minghan Xian, Chaker Fares, Ribhu Sharma, Mark E. Law, Fan Ren, Stephen J. Pearton
Summary: In order to maximize the breakdown voltage of vertical geometry beta-Ga2O3 rectifiers, N+ ion implantation was used to form resistive regions for edge termination at the anode contact periphery. Through simulations and experimental implementation, significant increases in breakdown voltage were achieved without affecting the on-state resistance and on/off ratios of the rectifiers. The optimized implanted edge termination structure successfully increased the breakdown voltage without increasing device resistance in vertical geometry Ga2O3 rectifiers.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Nanoscience & Nanotechnology
Chappel S. Thornton, Blair Tuttle, Emily Turner, Mark E. Law, Sokrates T. Pantelides, George T. Wang, Kevin S. Jones
Summary: Oxidation studies of Si/SiGe nanofins have shown that the diffusion rate of Ge along the Si/SiO2 interface is faster than in bulk Si. This finding suggests that the redistribution of Ge occurs through diffusion along the Si/SiO2 interface followed by reintroduction into substitutional positions in the crystalline Si.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Xinyi Xia, Jian-Sian Li, Ribhu Sharma, Fan Ren, Md Abu Jafar Rasel, Sergei Stepanoff, Nahid Al-Mamun, Aman Haque, Douglas E. Wolfe, Sushrut Modak, Leonid Chernyak, Mark E. Law, Ani Khachatrian, S. J. Pearton
Summary: This paper presents a review of experimental and simulation radiation damage results in Ga2O3. Ga2O3 is expected to have similar radiation resistance as GaN and SiC, but with orders of magnitude difference compared to GaAs. The study highlights the importance of examining all types of radiation, as Ga2O3 devices may be used in both space and terrestrial applications.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Thomas Weingartner, Mark E. Law
Summary: Accurate and fast Fermi-Dirac integral approximations are used in semiconductor device simulators for carrier concentration calculation. Similar integrals are used for carrier density computation in the subgap region of a superconductor. The difference lies in the density of states (DOS) functional used. Short series approximations, including Gaussian quadrature, are applied to compute the superconductor DOS integral and its Frechet derivatives. Comparisons with numeric integration solutions demonstrate a 600-fold reduction in integration time. A table of short series approximation roots and weights is provided, along with error plots for different temperatures of the niobium pair-breaking potential energy.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Physics, Applied
Chappel S. Thornton, Xiao Shen, Blair Tuttle, Xuebin Li, Mark E. Law, Sokrates T. Pantelides, George T. Wang, Kevin S. Jones
Summary: This paper investigates the diffusion and electrical activation of phosphorus in Si1-xGex during oxidation. The study reveals that phosphorus mainly diffuses to the SiGe-SiO2 interface and is electrically inactive at the interface. Through a combination of experiments and density functional theory calculations, it is proposed that Ge interstitials generated during SiGe oxidation drive the displacement of phosphorus atoms and a novel hopping mechanism of P-Ge split interstitials.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Lars Bjorndal, Nimesh Pokhrel, Thomas Weingartner, Polina Leger, Erin Patrick, Mark Law
Summary: Technology Computer Aided Design (TCAD) is being developed for superconductor electronics (SCE) with the inclusion of a model for surface roughness and statistical simulations. The AlOx tunnel barriers used in SCE have thicknesses similar to the surface roughness of sputtered niobium. This unique module is necessary for generating process-simulated structures and electrical simulations of the Nb/Al-AlOx/Nb junction stack.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Nanoscience & Nanotechnology
Chappel S. Thornton, Blair Tuttle, Emily Turner, Mark E. Law, Sokrates T. Pantelides, George T. Wang, Kevin S. Jones
Summary: A new Ge diffusion mechanism has been discovered that enables the formation of single-crystal Si nanowires and quantum dots in a defect-free, single-crystal SiGe matrix along the oxidizing interface of Si/SiGe nanostructures. The oxidation studies of Si/SiGe nanofins were conducted to understand this novel mechanism better. It was found that the activation energy for Ge diffusion along the sidewall is much lower than that for Ge diffusion in bulk Si, indicating a different diffusion behavior.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Proceedings Paper
Engineering, Manufacturing
Thomas Weingartner, Mark E. Law, Keith Green, Andrew Thomas, Henry Johnson, Polina Leger
Summary: In this study, a finite element quasi-Fermi implementation of a generalized first principles strain model for silicon is presented. Various strain effects in silicon, such as mobility, bandgap, density of states, piezo-Hall, temperature, and doping models, are encompassed using first principles and the finite element quasi-Fermi method to write a conductivity tensor with appropriate carrier relationships.
2021 INTERNATIONAL CONFERENCE ON SIMULATION OF SEMICONDUCTOR PROCESSES AND DEVICES (SISPAD 2021)
(2021)
