Orientation effects on the resistivity of copper grain boundaries are studied systematically with two different atomistic tight binding methods. A methodology is developed to model the resistivity of grain boundaries using the Embedded Atom Model, tight binding methods and non-equilibrum Green's functions (NEGF). The methodology is validated against first principles calculations for small, ultra-thin body grain boundaries (<5nm) with 6.4% deviation in the resistivity. A statistical ensemble of 600 large, random structures with grains is studied. For structures with three grains, it is found that the distribution of resistivities is close to normal. Finally, a compact model for grain boundary resistivity is constructed based on a neural network.
Development and validation of an electron temperature-dependent interaction potential for silicon and copper for the use in atomistic simulations of laser ablation
Nanoindentation is a powerful tool capable of providing fundamental insights of material elastic and plastic response at the nanoscale. Alloys at nanoscale are particularly interesting as the local heterogeneity and deformation mechanism revealed by atomistic study offers a better way to understand hardening mechanism to build a stronger material. In this work, nanoindentation in Al-Cu alloys are studied using atomistic simulations to investigate the effects of loading direction, alloying percentages of Cu via dislocation-driven mechanisms. Also, a low-fidelity finite element (FE) model has be…
The atomic cluster expansion is a general polynomial expansion of the atomic energy in multi-atom basis functions. Here we implement the atomic cluster expansion in the performant C++ code \verb+PACE+ that is suitable for use in large scale atomistic simulations. We briefly review the atomic cluster expansion and give detailed expressions for energies and forces as well as efficient algorithms for their evaluation. We demonstrate that the atomic cluster expansion as implemented in \verb+PACE+ shifts a previously established Pareto front for machine learning interatomic potentials towards faste…
Accelerated Discovery of Topological Conductors for Nanoscale Interconnects
NORDITA, KTH Royal Institute of Technology and Stockholm University（北欧理论粒子物理研究所，皇家理工学院和斯德哥尔摩大学）；University of Connecticut（康涅狄格大学）；Northwestern University（西北大学）；IBM Thomas J. Watson Research Center（IBM托马斯·J·沃森研究中心）；National Yang Ming Chiao Tung University（国立阳明交通大学）；Academia Sinica（中央研究院）
First-principles high-throughput screening of ruthenium compounds for advanced interconnects
Department of Electronics Engineering, Incheon National University（仁川国立大学电子工程系）；Research Institute for Engineering and Technology, Incheon National University（仁川国立大学工程技术研究院）
The phase behavior of grain boundaries can have a strong influence on interfacial properties. Little is known about the emergence of grain boundary phases in elemental metal systems and how they transform. Here, we observe the nanoscale patterning of a grain boundary by two alternating grain boundary phases with distinct atomic structures in elemental copper by atomic resolution imaging. The same grain boundary phases are found by grain boundary structure search indicating a first-order transformation. Finite temperature atomistic simulations reveal a congruent, diffusionless transition betwee…
Owing to the advances in computational techniques and the increase in computational power, atomistic simulations of materials can simulate large systems with higher accuracy. Complex phenomena can be observed in such state-of-the-art atomistic simulations. However, it has become increasingly difficult to understand what is actually happening and mechanisms, for example, in molecular dynamics (MD) simulations. We propose an unsupervised machine learning method to analyze the local structure around a target atom. The proposed method, which uses the two-step locality preserving projections (TS-LP…
Control of Cu morphology on TaN barrier and combined Ru-TaN barrier/liner substrates for nanoscale interconnects from atomistic kinetic Monte Carlo simulations
本研究利用基于 DFT 能垒的原子尺度 kMC 模拟，考察不同 Ru 掺入量、温度和分压下 TaN 及 Ru-TaN 复合阻挡层/衬垫层上的 Cu 沉积形貌，以优化纳米互连体积。
Revealing the Atomic-Scale Structure of the Copper Sulfuric Acid Interface
Max Planck Institute for Sustainable Materials（马克斯·普朗克可持续材料研究所）；Gyeongsang National University（庆尚国立大学）；Imperial College London（伦敦帝国理工学院）；University of Toronto（多伦多大学）；Univ Rouen Normandie, CNRS, INSA Rouen Normandie, Groupe de Physique des Matériaux（鲁昂诺曼底大学，法国国家科学研究中心，鲁昂诺曼底国立应用科学学院，物质物理研究组）；KU Leuven（荷语鲁汶大学）
Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a di…
Micron-scale single-crystal nanowires of metallic TaSe3, a material that forms -Ta-Se3-Ta-Se3- stacks separated from one another by a tubular van der Waals (vdW) gap, have been synthesized using chemical vapor deposition (CVD) on a SiO2/Si substrate, in a process compatible with semiconductor industry requirements. Their electrical resistivity was found unaffected by downscaling from the bulk to as little as 7 nm in width and height, in striking contrast to the resistivity of copper for the same dimensions. While the bulk resistivity of TaSe3 is substantially higher than that of bulk copper, a…
Anisotropic core-shell model of a nano-grained polycrystal, proposed recently for nanocrystalline copper, is applied to estimate elastic effective properties for a set of crystals of cubic symmetry. Materials selected for analysis differ in the lattice geometry (face-centered cubic vs. body-centered cubic) as well as the value of a Zener factor: a ratio of two shear moduli defining elastic anisotropy of a cubic crystal. The predictions are verified by means of the atomistic simulations. The dependence of the overall bulk and shear moduli on the average grain diameter is analysed. In the mean-f…
Role of defects in the thermodynamic stability of grain boundary phases at asymmetric tilt boundaries in copper
Max Planck Institute for Sustainable Materials（马克斯·普朗克可持续材料研究所）；Interdisciplinary Centre for Advanced Materials Simulation (ICAMS)（先进材料模拟跨学科中心）；Ruhr-Universität Bochum（波鸿鲁尔大学）；Research Center Future Energy Materials and Systems（未来能源材料与系统研究中心）；Faculty of Physics and Astronomy（物理与天文学学院）
Smart energy models for atomistic simulations using a DFT-driven multifidelity approach
KTH Royal Institute of Technology（皇家理工学院）；Università della Svizzera Italiana（瑞士意大利语区大学）；CEA, Université Paris-Saclay（法国原子能委员会（巴黎萨克雷大学））；EDF–-R&D（法国电力公司研发中心）；SCK•CEN（比利时核研究中心（SCK•CEN））
Oriented attachment (OA) has become a well-recognized mechanism for the growth of metal, ceramic, and biomineral crystals. While many computational and experimental studies of OA have shown that particles can attach with some misorientation then rotate to remove adjoining grain boundaries, the underlying atomistic pathways for this "Imperfect OA" process remain the subject of debate. In this study, molecular dynamics and in situ TEM were used to probe the crystallographic evolution of up to 30 gold and copper nanoparticles during aggregation. It was found that Imperfect OA occurs because (1) g…
