Nonequilibrium 2D-3D materials: strain, defects, kinetics for better functionality
Abstract
Recent years brought the ever-growing family of 2D materials from theory or experimental discovery to industrially-viable wafer-scal,e syntheses. Structurally flawless materials, although still sought after, were found to be somewhat limited in property modulation., While non-equilibrium materials, kept in strained, deformed states, or even rapidly quenched from far non-equilibrium, do gain risi,ng scientific interest. A promising yet simple avenue to non-equilibrium 2D materials is a static deformation, controlling the p,roperties. Growing or placing a 2D layer on a substrate with non-Euclidean topography, of non-zero local Gaussian curvature, can pr,oduce a variety of effects ? from elastic strain fields to the formation of individual topological lattice defects or long-range gra,in boundaries (GB) ? all driving material-layer away from the ground-s,to explore the processes and results, we have previously developed an on-the-fly off-lattice kinetic Monte Carlo (kMC) simulator, wi,ce the kMC framework in efficiency, refine the layer-substrate interaction, and add non-carbon layers. The methodology would enable,the large-scale study of the precise defect patterns formed to comply with 3D substrate topography. (ii) Expanding on the previous s,s route. Even purely elastic deformations hold great potential for functionality (iii). To enable simulations of the larger def,ormation levels beyond the applicability of the Foppl-von Karman equation (>13%), the elasticity terms within the phase field model,(PFM) will be modified. This will be applied to further study graphene electron-optics devices, such as lenses and collimators that,rely on the alteredelectron dynamics (with K and K? valleys separation) in strain-induced pseudo-magnetic field, as well as anisotro,pic confinement and the formation of flat bands within single-layer 2D semiconductors (instead of hard-to-control twisted bilayer sy,stems). With monolayer h-BN on a bi-sinusoidal (egg-crate) surface the flat bands for electrons can be achieved; a merely sine-undul,ated bilayer h-BN is also a promising platform for new physics to be optimized and explored. The collected data will be used to, try and tackle challenge of an inverse design problem (iv): for a desired property the algorithm (commonly ML) should determine the, necessary defect and/or strain configuration, finally identifying the required substrate topography. An entirely different app,roach to the non-equilibrium material creation is via flash processes providing rapid energy to the system as electric current, or l,ight (v). We aim to bring the value of comprehensive ab initio models of flash sintering by revealing the key mechanisms. This will, include evaluating ionic charges in the system, with a focus on charged and neutral defects, followed by consideration of the bulk,and surface diffusion in presence of excessive charges, doping, or non-equilibrium e? and h+ ?modified Fermi? distribution, far from, equilibrium. Atomistic insight will be obtained into the mechanism of the recent flash syntheses of the metastable 2D and 3D materi,als. The project will quantify nano?engineering of the low-D materials into non-equilibrium forms, by means of non-tri,vial, expressly non-planar topography substrates-templates. We will further establish topography effects on physical properties: con,trol of electronic transport, flat bands for correlated phases, surface catalysis, optics, etc. Non-equilibrium effects from hot ele,ctrons to ion-diffusion will be explored to assist in the understanding of important flash-sintering processes.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 07, 2022
- Source ID
- N000142212788
Entities
People
- Boris I Yakobson
Organizations
- Office of Naval Research
- Rice University
- United States Navy