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| 3. |
- Han, Delong, et al.
(författare)
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Analysis of Raman scattering from inclined GeSn/Ge dual-nanowire heterostructure on Ge(1 1 1) substrate
- 2019
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 463, s. 581-586
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the Raman spectra of GeSn/Ge dual-nanowire heterostructure grown on Ge(1 1 1) substrate are systematically analyzed within the framework of anisotropic elasticity and lattice dynamical theory. Based on the experimental samples grown by molecular beam epitaxy, the partially covered dual nanowires standing along 〈1 1 0〉 direction are modeled and the heterostructure presents effective elastic strain relaxation due to the free surfaces. The simulations show that the Raman shift of GeSn nanowire is mainly affected by the Sn content while the influences of strain become less important with the increase of thickness ratio. For Ge nanowire, the peak of Raman spectrum merely moves with Sn content, but the spectrum possesses asymmetric broadening induced by the non-uniform strain distribution. The red-shift and intensity reduction of the total Raman spectrum of dual nanowires are observed when the Sn content increases. Moreover, an analytic fitting expression for Raman peak position is obtained based on the numerical results and is expected to serve as a reference to estimate the Sn content in GeSn/Ge dual-nanowire heterostructure.
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| 4. |
- Ye, H., et al.
(författare)
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Dislocation-induced composition profile in alloy semiconductors
- 2010
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098. ; 150:29-30, s. 1275-1278
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel computational method by combining the finite element method and the method of moving asymptotes to study the dislocation-induced composition profile in alloy semiconductors. Segregated cylindrical nanoscale regions appear around the dislocation core. We find that the dominant driving force of non-uniform composition is strain contribution. Moreover, the method can be applied to the dislocated nanoscale heterostructures which are inaccessible by atomic treatment. (C) 2010 Elsevier Ltd. All rights reserved.
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| 5. |
- Wu, Jingnan, et al.
(författare)
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Carboxylate substituted pyrazine: A simple and low-cost building block for novel wide bandgap polymer donor enables 15.3% efficiency in organic solar cells
- 2021
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 82
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Tidskriftsartikel (refereegranskat)abstract
- In addition to high power conversion efficiency (PCE) and good stability, the low-cost of photovoltaic materials is also very important for the practical application of organic solar cells (OSCs). Herein, we synthesized a carboxylate substituted pyrazine-based electron-deficient building block (DTCPz) with a simple structure and low synthetic cost, and then developed a novel wide bandgap polymer donor PFBCPZ. Due to the synergistic electron-withdrawing effects of the fluorination in donor unit (BDT-TF) and esterification and C=N double-bond in DTCPz unit, PFBCPZ shows a deeper HOMO level of −5.60 eV, a strong intermolecular π-π interaction, good crystallinity and stacking, and high hole-mobility of 2.11 × 10−3 cm2 V−1 s−1. Matched with a low bandgap acceptor IT-4F, excellent charge transfer, weak recombination, and small non-radiative energy loss in OSCs was achieved, resulting in an impressive fill factor of 0.785 and a high open-circuit voltage of 0.92 V. As a result, a PCE of up to 15.3% is obtained in OSCs, which is the highest value in the IT-4F-based binary OSCs so far and indicates that low-cost DTCPz with a simple structure is a promising building block to construct high-performance polymer donors for application in efficient OSCs.
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| 6. |
- Ye, X., et al.
(författare)
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Design and implementation of a real-time power management strategy for a parallel hybrid electric bus
- 2014
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070.
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Tidskriftsartikel (refereegranskat)abstract
- A real-time energy management strategy derived from an equivalent consumption minimization strategy for a parallel hybrid electric bus is introduced. Although an equivalent consumption minimization strategy is a near-optimal control strategy for the power management problems of hybrid electric vehicles, the computation cost and the driveability requirements are still barriers for it to be directly implemented on real-time controllers. This paper analyses the controller characteristics of the equivalent consumption minimization strategy based on the Willans line model for an internal-combustion engine and an electric motor. A two-step method is proposed to simplify and approximate the standard equivalent consumption minimization strategy controller. The strategy for the proposed controller, which is calledthe Willans line–equivalent consumption minimization strategy, can reduce the computation cost of optimization and can guarantee near-optimum fuel economy, while improving the vehicle driveability. The proposed controller is then validated by offline simulation and an onboard bench test. A backward simulation is conducted to test the fuel economy performance of the controller simplified from the two steps, together with dynamic programming and an equivalent consumption minimization strategy based on look-up tables. Then the controller is tuned by a high-fidelity forward simulationto explore the trade-off between the fuel economy and the driveability. Finally, a bench test with real powertrain components is presented to illustrate the effectiveness of the proposed methodology.
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| 7. |
- Chen, H., et al.
(författare)
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Unprecedented non-hysteretic superelasticity of [001]-oriented NiCoFeGa single crystals
- 2020
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Ingår i: Nature Materials. - : Nature Research. - 1476-1122 .- 1476-4660.
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Tidskriftsartikel (refereegranskat)abstract
- Superelasticity associated with the martensitic transformation has found a broad range of engineering applications1,2. However, the intrinsic hysteresis3 and temperature sensitivity4 of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we report a large superelasticity up to 15.2% strain in [001]-oriented NiCoFeGa single crystals, exhibiting non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In situ synchrotron X-ray diffraction measurements show that the superelasticity is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the superelasticity. The discovery of the large elasticity related to the entangled structure paves the way for exploiting elastic strain engineering and development of related functional materials.
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| 8. |
- Du, W., et al.
(författare)
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Study into high temperature reliability of isotropic conductive adhesive
- 2011
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Ingår i: Proceedings - 12th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2011, Shanghai, 8-11 August 2011. - 9781457717680 ; , s. 1053-1055
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Konferensbidrag (refereegranskat)abstract
- With the rapid development of technologies for high density assembly and packaging in electronic industry, isotropic conductive adhesive (ICA) has been paid more and more attention as a potential substitute for solder, due to its advantages of low processing temperature, simple processing conditions and good manufacturability. However, studies into the reliability of ICA are not as abundant as those of solder. As a composite material, the failure feasibility of ICA not only depends not only on the variation in performance of different constituent parts, such as high temperature aging of the polymer, aging due to moisture absorption and oxidization of filler particles, but also on interface changes. Thus, the failure mechanism of ICA seems to be complicated and studies into the reliability of ICA are also necessary. Reliability in humidity and heat has been investigated in previous works, and in this paper high temperature reliability will be studied as a comparison. Some reliability tests and results will be given and some failure mechanisms discussed. Finally, we present some discussion about the further optimization of reliability for follow-up studies.
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| 9. |
- Fan, Q., et al.
(författare)
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The effect of functionalized silver on properties of conductive adhesives
- 2011
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Ingår i: Proceedings - 12th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2011, Shanghai, 8-11 August 2011. - 9781457717680 ; , s. 423-425
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Konferensbidrag (refereegranskat)abstract
- This research used low molecular surface modifiers and observed that chemisorptions took place through the formation of a bond between silver surface and an adsorbed molecule, which improved the dispersion of silver flakes in the organic resin. Results of shear viscosity, bulk resistivity etc. showed that by using these low molecular organic functionalizers, isotropic conductive adhesives (ICAs) with lower shear viscosity and better electrical conductivity at high silver fillers content were obtained. Different processing methods and different matrixes were compared.
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| 10. |
- Fan, Q., et al.
(författare)
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The effect of functionalized silver on rheological and electrical properties of conductive adhesives
- 2011
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781607682356 ; 34:1, s. 811-816
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Konferensbidrag (refereegranskat)abstract
- This research used low molecular surface modifiers, and observed that chemisorptions took place through the formation of a bond between silver surface and an adsorbed molecule, which improved the dispersion of silver flakes in the organic resin. Several different functionalizers, such as thioglycolic acid, silane and di-acid, were used to functionalize the silver surface. Results of shear viscosity, bulk resistivity etc. showed that by using these low molecular organic functionalizers, isotropic conductive adhesives (ICAs) with lower shear viscosity and better electrical conductivity at high silver fillers content were obtained. The adipic acid had the greatest effect on the rheological and electrical property of ICAs, so its weight percentage in silver flakes was also optimized; ICAs displayed the maximum electrical conductivity when there was 0.5 wt% of silver flakes.
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