scholarly journals High Fidelity Polycrystalline CdTe/CdS Heterostructures via Molecular Dynamics

MRS Advances ◽  
2017 ◽  
Vol 2 (53) ◽  
pp. 3225-3230 ◽  
Author(s):  
Rodolfo Aguirre ◽  
Jose J. Chavez ◽  
Xiaowang Zhou ◽  
David Zubia
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Small Region ◽  
Composition Analysis ◽  
Cross Sectional ◽  
Solar Cell Efficiency ◽  
Cell Efficiency ◽  
Cds Film ◽  
Dynamics Simulations ◽  
Grain Boundary Motion

ABSTRACTMolecular dynamics simulations of polycrystalline growth of CdTe/CdS heterostructures have been performed. First, CdS was deposited on an amorphous CdS substrate, forming a polycrystalline film. Subsequently, CdTe was deposited on top of the polycrystalline CdS film. Cross-sectional images show grain formation at early stages of the CdS growth. During CdTe deposition, the CdS structure remains almost unchanged. Concurrently, CdTe grain boundary motion was detected after the first 24.4 nanoseconds of CdTe deposition. With the elapse of time, this grain boundary pins along the CdS/CdTe interface, leaving only a small region of epitaxial growth. CdTe grains are larger than CdS grains in agreement with experimental observations in the literature. Crystal phase analysis shows that zinc blende structure dominates over the wurtzite structure inside both CdS and CdTe grains. Composition analysis shows Te and S diffusion to the CdS and CdTe films, respectively. These simulated results may stimulate new ideas for studying and improving CdTe solar cell efficiency.

scholarly journals Grain Boundary Motion under Dynamic Loading: Mechanism and Large-Scale Molecular Dynamics Simulations

2013 ◽  
Vol 1 (4) ◽  
pp. 220-227 ◽  
Author(s):  
Christian Brandl ◽  
Timothy C. Germann ◽  
Alejandro G. Perez-Bergquist ◽  
Ellen K. Cerreta
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Molecular Dynamics Simulations ◽  
Dynamic Loading ◽  
Large Scale ◽  
Boundary Motion ◽  
Dynamics Simulations ◽  
Grain Boundary Motion

Atomic Mechanisms of Grain Boundary Motion

2005 ◽  
Vol 502 ◽  
pp. 157-162 ◽  
Author(s):  
A. Suzuki ◽  
Yuri M. Mishin
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Geometric Model ◽  
Lattice Rotation ◽  
Shear Stresses ◽  
Translation Rate ◽  
Embedded Atom ◽  
Local Lattice ◽  
Symmetrical Tilt ◽  
Grain Boundary Motion

We present results of atomistic computer simulations of spontaneous and stress-induced grain boundary (GB) migration in copper. Several symmetrical tilt GBs have been studied using the embedded-atom method and molecular dynamics. The GBs are observed to spontaneously migrate in a random manner. This spontaneous GB motion is always accompanied by relative translations of the grains parallel to the GB plane. Furthermore, external shear stresses applied parallel to the GB and normal to the tilt axis induce GB migration. Strong coupling is observed between the normal GB velocity vn and the grain translation rate v||. The mechanism of GB motion is established to be local lattice rotation within the GB core that does not involve any GB diffusion or sliding. The coupling constant between vn and v|| predicted within a simple geometric model accurately matches the molecular dynamics observations.

Study on Nanolithography Process of Polycrystalline Copper Using Molecular Dynamic Simulation

2007 ◽  
Vol 340-341 ◽  
pp. 961-966
Author(s):  
Chan Il Kim ◽  
Young Suk Kim ◽  
Sang Il Hyun ◽  
Seung Han Yang ◽  
Jun Young Park ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Molecular Dynamic Simulation ◽  
Molecular Dynamic ◽  
Dynamic Simulation ◽  
Diamond Like Carbon ◽  
Polycrystalline Copper ◽  
Berkovich Indenter ◽  
Contact Surfaces ◽  
Dynamics Simulations

Molecular dynamics simulations are performed to verify the effect of grain boundary on nanolithography process. The model with about two hundred thousand copper (Cu) atoms is composed of two different crystal orientations of which contact surfaces are (101) and (001) planes. The grain boundary is located on the center of model and has 45 degreeangle in xz-plane. The tool is made of diamond-like-carbon with the shape of Berkovich indenter. As the tool is indented and plowed on the surface, dislocations are generated. Moreover, during the plowing process, the steps as well as the typical pile-ups are formed in front of the tool. These defects propagate into the surface of the substrate. As the tool approaches to the grain boundary, the defects are seen to be accumulated near the grain boundary. The shape of the grain boundary is also significantly deformed after the tool passes it. We observed the forces exerted on the tool by the contact with substrate, so that the friction coefficients can be obtained to address the effect of the grain boundary on the friction characteristics.

scholarly journals Deformation Behavior of Nanocrystalline Body-Centered Cubic Iron with Segregated, Foreign Interstitial: A Molecular Dynamics Study

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5351
Author(s):  
Ahmed Tamer AlMotasem ◽  
Matthias Posselt ◽  
Tomas Polcar
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Deformation Behavior ◽  
Large Scale ◽  
Grain Boundary Sliding ◽  
Carbon And Nitrogen ◽  
Embedded Atom ◽  
Boundary Sliding ◽  
Dynamics Simulations

In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type.

Mechanical properties of cellulose nanofibrils determined through atomistic molecular dynamics simulations

2012 ◽  
Vol 27 (2) ◽  
pp. 282-286 ◽  
Author(s):  
Jukka Ketoja ◽  
Sami Paavilainen ◽  
James Liam McWhirter ◽  
Tomasz Róg ◽  
Juha Järvinen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Elastic Modulus ◽  
Molecular Dynamics Simulations ◽  
Elastic Constants ◽  
Cellulose Nanofibrils ◽  
Amorphous Cellulose ◽  
Cross Sectional ◽  
Elementary Fibrils ◽  
Dynamics Simulations

Abstract We have carried out atomistic molecular dynamics simulations to study the mechanical properties of cellulose nanofibrils in water and ethanol. The studied elementary fibrils consisted of regions having 34 or 36 cellulose chains whose cross-sectional diameter across the fibril was roughly 3.4 nm. The models used in simulations included both crystalline and non-crystalline regions, where the latter were designed to describe the essentials parts of amorphous cellulose nanofibrils. We examined different numbers of connecting chains between the crystallites, and found out that the elastic constants, inelastic deformations, and strength of the fibril depend on this number. For example, the elastic modulus for the whole fibril can be estimated to increase by 4 GPa for each additional connecting chain.

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