The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Ju Li - One of the best experts on this subject based on the ideXlab platform.
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achieving 5 9 Elastic Strain in kilograms of metallic glasses nanoscopic Strain engineering goes macro
Materials Today, 2020Co-Authors: Junsong Zhang, Daqiang Jiang, Hong Yang, Zhigang Wu, Sam Bakhtiari, Fakhrodin Motazedian, Ju LiAbstract:Abstract The ideal Elastic limit is the upper bound of the achievable strength and Elastic Strain of solids. However, the Elastic Strains that bulk materials can sustain are usually below 2%, due to the localization of inElastic deformations at the lattice scale. In this study, we achieved >5% Elastic Strain in bulk quantity of metallic glass, by exploiting the more uniform and smaller-magnitude atomic-scale lattice Strains of martensitic transformation as a loading medium in a bulk metallic nanocomposite. The self-limiting nature of martensitic transformation helps to prevent lattice Strain transfer that leads to the localization of deformation and damage. This lattice Strain egalitarian strategy enables bulk metallic materials in kilogram-quantity to achieve near-ideal Elastic limit. This concept is verified in a model in situ bulk amorphous (TiNiFe)-nanocrystalline (TiNi(Fe)) composite, in which the TiNiFe amorphous matrix exhibits a maximum tensile Elastic Strain of ∼5.9%, which approaches its theoretical Elastic limit. As a result, the model bulk composite possesses a large recoverable Strain of ∼7%, a maximum tensile strength of above 2 GPa, and a large Elastic resilience of ∼79.4 MJ/m3. The recoverable Strain and Elastic resilience are unmatched by known high strength bulk metallic materials. This design concept opens new opportunities for the development of high-performance bulk materials and Elastic Strain engineering of the physiochemical properties of glasses.
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deep Elastic Strain engineering of bandgap through machine learning
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Evgenii Tsymbalov, S Suresh, Alexander V Shapeev, Ju LiAbstract:Nanoscale specimens of semiconductor materials as diverse as silicon and diamond are now known to be deformable to large Elastic Strains without inElastic relaxation. These discoveries harbinger a new age of deep Elastic Strain engineering of the band structure and device performance of electronic materials. Many possibilities remain to be investigated as to what pure silicon can do as the most versatile electronic material and what an ultrawide bandgap material such as diamond, with many appealing functional figures of merit, can offer after overcoming its present commercial immaturity. Deep Elastic Strain engineering explores full six-dimensional space of admissible nonlinear Elastic Strain and its effects on physical properties. Here we present a general method that combines machine learning and ab initio calculations to guide Strain engineering whereby material properties and performance could be designed. This method invokes recent advances in the field of artificial intelligence by utilizing a limited amount of ab initio data for the training of a surrogate model, predicting electronic bandgap within an accuracy of 8 meV. Our model is capable of discovering the indirect-to-direct bandgap transition and semiconductor-to-metal transition in silicon by scanning the entire Strain space. It is also able to identify the most energy-efficient Strain pathways that would transform diamond from an ultrawide-bandgap material to a smaller-bandgap semiconductor. A broad framework is presented to tailor any target figure of merit by recourse to deep Elastic Strain engineering and machine learning for a variety of applications in microelectronics, optoelectronics, photonics, and energy technologies.
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approaching the ideal Elastic Strain limit in silicon nanowires
Science Advances, 2016Co-Authors: Hongti Zhang, Ju Li, J Tersoff, Shang Xu, Huixin Chen, Qiaobao Zhang, Kaili Zhang, Yong Yang, K N Tu, Yang LuAbstract:Achieving high Elasticity for silicon (Si) nanowires, one of the most important and versatile building blocks in nanoelectronics, would enable their application in flexible electronics and bio-nano interfaces. We show that vapor-liquid-solid–grown single-crystalline Si nanowires with diameters of ~100 nm can be repeatedly stretched above 10% Elastic Strain at room temperature, approaching the theoretical Elastic limit of silicon (17 to 20%). A few samples even reached ~16% tensile Strain, with estimated fracture stress up to ~20 GPa. The deformations were fully reversible and hysteresis-free under loading-unloading tests with varied Strain rates, and the failures still occurred in brittle fracture, with no visible sign of plasticity. The ability to achieve this “deep ultra-strength” for Si nanowires can be attributed mainly to their pristine, defect-scarce, nanosized single-crystalline structure and atomically smooth surfaces. This result indicates that semiconductor nanowires could have ultra-large Elasticity with tunable band structures for promising “Elastic Strain engineering” applications.
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tailoring exciton dynamics by Elastic Strain gradient in semiconductors
Advanced Materials, 2014Co-Authors: Xuewen Fu, Cong Su, Qiang Fu, Zhimin Liao, Jun Xu, Ji Feng, Ju Li, Dapeng YuAbstract:: In purely bent ZnO microwires, the excitons can be effectively driven and concentrated by the Elastic Strain-gradient towards the tensile outer side of the purely bent wire. Experimental and theoretical approaches are combined to investigate the dynamics of excitons in an inhomogeneous Strain field with a uniform Elastic Strain-gradient. Cathodoluminescence spectroscopy analysis on purely bent ZnO microwires verifies that excitons can be effectively driven and concentrated along the Elastic Strain-gradient.
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Elastic Strain engineering for unprecedented materials properties
Mrs Bulletin, 2014Co-Authors: Ju Li, Zhiwei ShanAbstract:“Smaller is stronger.” Nanostructured materials such as thin films, nanowires, nanoparticles, bulk nanocomposites, and atomic sheets can withstand non-hydrostatic (e.g., tensile or shear) stresses up to a significant fraction of their ideal strength without inElastic relaxation by plasticity or fracture. Large Elastic Strains, up to ∼10%, can be generated by epitaxy or by external loading on small-volume or bulk-scale nanomaterials and can be spatially homogeneous or inhomogeneous. This leads to new possibilities for tuning the physical and chemical properties of a material, such as electronic, optical, magnetic, phononic, and catalytic properties, by varying the six-dimensional Elastic Strain as continuous variables. By controlling the Elastic Strain field statically or dynamically, a much larger parameter space opens up for optimizing the functional properties of materials, which gives new meaning to Richard Feynman’s 1959 statement, “there’s plenty of room at the bottom.”
Michael S. Shur - One of the best experts on this subject based on the ideXlab platform.
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piezoelectric doping and Elastic Strain relaxation in algan gan heterostructure field effect transistors
Applied Physics Letters, 1998Co-Authors: A. D. Bykhovski, R Gaska, Michael S. ShurAbstract:We calculate the sheet electron density induced by the piezoelectric effect in AlxGa1−xN–GaN heterostructure field effect transistors. This density is limited by the Elastic Strain relaxation, which depends on AlGaN barrier layer thickness and on the Al molar fraction in the barrier layer. Piezoelectric doping is more important in structures with larger Al content and thinner barrier layers. These results agree with our experimental data.
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Elastic Strain relaxation and piezoeffect in gan aln gan algan and gan ingan superlattices
Journal of Applied Physics, 1997Co-Authors: A. D. Bykhovski, B.l. Gelmont, Michael S. ShurAbstract:We calculated the Elastic Strain relaxation in (GaN)n-(AlN)n, (GaN)n(AlxGa1−xN)n and (GaN)n(InxGa1−xN)n superlattices where n is the number of layers in the superlattice cell. This calculation and a similar calculation for a semiconductor–insulator–semiconductor structure allowed us to determine the lower and upper bounds for the Elastic Strain relaxation in (GaN)m(AlN)n superlattices with arbitrary n/m ratios, i.e., we determine a full range of the critical thicknesses for GaNm(AlN)n superlattices. The obtained theoretical results can also be applied to other superlattices based on III nitrides and their solid solutions. Our theory agrees with the experimental data for GaN-AlN superlattices. Also, we show that the piezoelectric effect may cause a large shift of the absorption edge in defect-free GaNm(AlxGa1−xN)n superlattices.
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Elastic Strain relaxation and piezoeffect in GaN-AIN, GaN-AIGaN and GaN-InGaN superlattices
Journal of Applied Physics, 1997Co-Authors: A. D. Bykhovski, B.l. Gelmont, Michael S. ShurAbstract:We calculated the Elastic Strain relaxation in (GaN)n-(AlN)n, (GaN)n(AlxGa1−xN)n and (GaN)n(InxGa1−xN)n superlattices where n is the number of layers in the superlattice cell. This calculation and a similar calculation for a semiconductor–insulator–semiconductor structure allowed us to determine the lower and upper bounds for the Elastic Strain relaxation in (GaN)m(AlN)n superlattices with arbitrary n/m ratios, i.e., we determine a full range of the critical thicknesses for GaNm(AlN)n superlattices. The obtained theoretical results can also be applied to other superlattices based on III nitrides and their solid solutions. Our theory agrees with the experimental data for GaN-AlN superlattices. Also, we show that the piezoelectric effect may cause a large shift of the absorption edge in defect-free GaNm(AlxGa1−xN)n superlattices. © 1997 American Institute of Physics. © 1997 American Institute of Physics
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Elastic Strain relaxation in GaN–AlN–GaN semiconductor–insulator–semiconductor structures
Journal of Applied Physics, 1995Co-Authors: A. D. Bykhovski, B.l. Gelmont, Michael S. ShurAbstract:We calculated the Elastic Strain relaxation in wurtzite GaN–AlN–GaN semiconductor–insulator–semiconductor (SIS) structures. Elastic Strain tensor components, Elastic energy, the density of the misfit dislocations, and the other parameters of the system were obtained as functions of the AlN layer thickness. Theoretical values of the Elastic Strain relaxation are in satisfactory agreement with experimental data extracted from the capacitance‐voltage (C‐V) characteristics of GaN–AlN–GaN SIS structures. Our results confirm that the gradual relaxation process starts from 30 A AlN film thickness. The uniform contributions to the Elastic Strain tensor components decrease by approximately an order of magnitude when the film thickness increases from 30 to 100 A. Commensurate with this decrease is an increase in a nonuniform contribution of the misfit dislocations. The dislocation interactions lead to redistribution of dislocations within the 30–60 A range of AlN film thicknesses.
Dapeng Yu - One of the best experts on this subject based on the ideXlab platform.
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tailoring exciton dynamics by Elastic Strain gradient in semiconductors
Advanced Materials, 2014Co-Authors: Xuewen Fu, Cong Su, Qiang Fu, Zhimin Liao, Jun Xu, Ji Feng, Ju Li, Dapeng YuAbstract:: In purely bent ZnO microwires, the excitons can be effectively driven and concentrated by the Elastic Strain-gradient towards the tensile outer side of the purely bent wire. Experimental and theoretical approaches are combined to investigate the dynamics of excitons in an inhomogeneous Strain field with a uniform Elastic Strain-gradient. Cathodoluminescence spectroscopy analysis on purely bent ZnO microwires verifies that excitons can be effectively driven and concentrated along the Elastic Strain-gradient.
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Tailoring exciton dynamics by Elastic Strain-gradient in semiconductors
arXiv: Materials Science, 2013Co-Authors: Xuewen Fu, Cong Su, Qiang Fu, Jun Xu, Ji Feng, Ju Li, Dapeng YuAbstract:As device miniaturization approaches the atomic limit, it becomes highly desirable to exploit novel paradigms for tailoring electronic structures and carrier dynamics in materials. Elastic Strain can in principle be applied to achieve reversible and fast control of such properties, but it remains a great challenge to create and utilize precisely controlled inhomogeneous deformation in semiconductors. Here, we take a combined experimental and theoretical approach to demonstrate that Elastic Strain-gradient can be created controllably and reversibly in ZnO micro/nanowires. In particular, we show that the inhomogeneous Strain distribution creates an effective field that fundamentally alters the dynamics of the neutral excitons. As the basic principles behind these results are quite generic and applicable to most semiconductors, this work points to a novel route to a wide range of applications in electronics, optoelectronics, and photochemistry.
Cong Su - One of the best experts on this subject based on the ideXlab platform.
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tailoring exciton dynamics by Elastic Strain gradient in semiconductors
Advanced Materials, 2014Co-Authors: Xuewen Fu, Cong Su, Qiang Fu, Zhimin Liao, Jun Xu, Ji Feng, Ju Li, Dapeng YuAbstract:: In purely bent ZnO microwires, the excitons can be effectively driven and concentrated by the Elastic Strain-gradient towards the tensile outer side of the purely bent wire. Experimental and theoretical approaches are combined to investigate the dynamics of excitons in an inhomogeneous Strain field with a uniform Elastic Strain-gradient. Cathodoluminescence spectroscopy analysis on purely bent ZnO microwires verifies that excitons can be effectively driven and concentrated along the Elastic Strain-gradient.
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Tailoring exciton dynamics by Elastic Strain-gradient in semiconductors
arXiv: Materials Science, 2013Co-Authors: Xuewen Fu, Cong Su, Qiang Fu, Jun Xu, Ji Feng, Ju Li, Dapeng YuAbstract:As device miniaturization approaches the atomic limit, it becomes highly desirable to exploit novel paradigms for tailoring electronic structures and carrier dynamics in materials. Elastic Strain can in principle be applied to achieve reversible and fast control of such properties, but it remains a great challenge to create and utilize precisely controlled inhomogeneous deformation in semiconductors. Here, we take a combined experimental and theoretical approach to demonstrate that Elastic Strain-gradient can be created controllably and reversibly in ZnO micro/nanowires. In particular, we show that the inhomogeneous Strain distribution creates an effective field that fundamentally alters the dynamics of the neutral excitons. As the basic principles behind these results are quite generic and applicable to most semiconductors, this work points to a novel route to a wide range of applications in electronics, optoelectronics, and photochemistry.
A. D. Bykhovski - One of the best experts on this subject based on the ideXlab platform.
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piezoelectric doping and Elastic Strain relaxation in algan gan heterostructure field effect transistors
Applied Physics Letters, 1998Co-Authors: A. D. Bykhovski, R Gaska, Michael S. ShurAbstract:We calculate the sheet electron density induced by the piezoelectric effect in AlxGa1−xN–GaN heterostructure field effect transistors. This density is limited by the Elastic Strain relaxation, which depends on AlGaN barrier layer thickness and on the Al molar fraction in the barrier layer. Piezoelectric doping is more important in structures with larger Al content and thinner barrier layers. These results agree with our experimental data.
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Elastic Strain relaxation and piezoeffect in gan aln gan algan and gan ingan superlattices
Journal of Applied Physics, 1997Co-Authors: A. D. Bykhovski, B.l. Gelmont, Michael S. ShurAbstract:We calculated the Elastic Strain relaxation in (GaN)n-(AlN)n, (GaN)n(AlxGa1−xN)n and (GaN)n(InxGa1−xN)n superlattices where n is the number of layers in the superlattice cell. This calculation and a similar calculation for a semiconductor–insulator–semiconductor structure allowed us to determine the lower and upper bounds for the Elastic Strain relaxation in (GaN)m(AlN)n superlattices with arbitrary n/m ratios, i.e., we determine a full range of the critical thicknesses for GaNm(AlN)n superlattices. The obtained theoretical results can also be applied to other superlattices based on III nitrides and their solid solutions. Our theory agrees with the experimental data for GaN-AlN superlattices. Also, we show that the piezoelectric effect may cause a large shift of the absorption edge in defect-free GaNm(AlxGa1−xN)n superlattices.
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Elastic Strain relaxation and piezoeffect in GaN-AIN, GaN-AIGaN and GaN-InGaN superlattices
Journal of Applied Physics, 1997Co-Authors: A. D. Bykhovski, B.l. Gelmont, Michael S. ShurAbstract:We calculated the Elastic Strain relaxation in (GaN)n-(AlN)n, (GaN)n(AlxGa1−xN)n and (GaN)n(InxGa1−xN)n superlattices where n is the number of layers in the superlattice cell. This calculation and a similar calculation for a semiconductor–insulator–semiconductor structure allowed us to determine the lower and upper bounds for the Elastic Strain relaxation in (GaN)m(AlN)n superlattices with arbitrary n/m ratios, i.e., we determine a full range of the critical thicknesses for GaNm(AlN)n superlattices. The obtained theoretical results can also be applied to other superlattices based on III nitrides and their solid solutions. Our theory agrees with the experimental data for GaN-AlN superlattices. Also, we show that the piezoelectric effect may cause a large shift of the absorption edge in defect-free GaNm(AlxGa1−xN)n superlattices. © 1997 American Institute of Physics. © 1997 American Institute of Physics
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Elastic Strain relaxation in GaN–AlN–GaN semiconductor–insulator–semiconductor structures
Journal of Applied Physics, 1995Co-Authors: A. D. Bykhovski, B.l. Gelmont, Michael S. ShurAbstract:We calculated the Elastic Strain relaxation in wurtzite GaN–AlN–GaN semiconductor–insulator–semiconductor (SIS) structures. Elastic Strain tensor components, Elastic energy, the density of the misfit dislocations, and the other parameters of the system were obtained as functions of the AlN layer thickness. Theoretical values of the Elastic Strain relaxation are in satisfactory agreement with experimental data extracted from the capacitance‐voltage (C‐V) characteristics of GaN–AlN–GaN SIS structures. Our results confirm that the gradual relaxation process starts from 30 A AlN film thickness. The uniform contributions to the Elastic Strain tensor components decrease by approximately an order of magnitude when the film thickness increases from 30 to 100 A. Commensurate with this decrease is an increase in a nonuniform contribution of the misfit dislocations. The dislocation interactions lead to redistribution of dislocations within the 30–60 A range of AlN film thicknesses.