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Investigation of the cap layer for improved GeSn multiple quantum well laser performance

Optics Letters 2023年第7期48卷 1626-1629页

作者： Abernathy, Grey Ojo, Solomon Stanchu, Hryhorii Zhou, Yiyin Olorunsola, Oluwatobi Grant, Joshua Du, Wei Jheng, Yue-Tong Chang, Guo-En Li, Baohua Yu, Shui-Qing Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States Materials Science & Engineering Program University of Arkansas FayettevilleAR72701 United States Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States Department of Mechanical Engineering National Chung Cheng University Chiayi County62102 Taiwan Arktonics LLC 1339 South Pinnacle Drive FayettevilleAR72701 United States

The study of all-group-IV SiGeSn lasers has opened a new avenue to Si-based light sources. SiGeSn heterostructure and quantum well lasers have been successfully demonstrated in the past few years. It has been reported that, for multiple quantum well lasers, the optical confinement factor plays an important role in the net modal gain. In previous studies, adding a cap layer was proposed to increase the optical mode overlap with the active region and thereby improve the optical confinement factor of Fabry–Perot cavity lasers. In this work, SiGeSn/GeSn multiple quantum well (4-well) devices with various cap layer thicknesses, i.e., 0 (no cap), 190, 250, and 290 nm, are grown using a chemical vapor deposition reactor and characterized via optical pumping. While no-cap and thinner-cap devices only show spontaneous emission, the two thicker-cap devices exhibit lasing up to 77 K, with an emission peak at 2440 nm and a threshold of 214 kW/cm2 (250 nm cap device). The clear trend in device performance disclosed in this work provides guidance in device design for electrically injected SiGeSn quantum well lasers. © 2023 Optica Publishing Group.

关键词： Semiconductor quantum wells

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Vortex Formation of Active Particles within a Confined Geometry by Velocity Alignment

Vortex Formation of Active Particles within a Confined Geome...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Chen, Zhihan Ding, Hongru Zheng, Yuebing Materials Science & Engineering Program Texas Materials Institute The University of Texas at Austin AustinTX78712 United States Walker Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States

We have developed an optical feedback control system with synchronous control of active particles to study collective motion in nature. Fish-like vortex is observed within a circular confined geometry based on the par... 详细信息

ISBN: (纸本)9781957171258

关键词： Adaptive control systems

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Strong electron correlation-induced Mott-insulating electrides of Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)

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Matter and Radiation at Extremes 2024年第3期9卷 74-82页

作者： Ya Xu Lu Zheng Yunkun Zhang Zhuangfei Zhang QianQian Wang Yuewen Zhang Liangchao Chen Chao Fang Biao Wan Huiyang Gou Key Laboratory of Material Physics of Ministry of Education School of Physics and Laboratory of Zhongyuan LightZhengzhou UniversityZhengzhou 450052China School of Mechanical and Equipment Engineering Hebei University of EngineeringHandan 056038China Center for High Pressure Science and Technology Advanced Research Beijing 100094China

The presence of interstitial electrons in electrides endows them with interesting attributes,such as low work function,high carrier concentration,and unique magnetic *** knowledge and understanding of electrides are thus of both scientific and technological ***,we employ first-principles calculations to investigate Mott-insulating Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)electrides with Mn_(5)Si_(3)-type structure,in which half-filled interstitial electrons serve as ions and are *** Mott-insulating property is induced by strong electron correlation between the nearest interstitial electrons,resulting in spin splitting and a separation between occupied and unoccupied *** half-filled antiferromagnetic configuration and localization of the interstitial electrons are critical for the Mott-insulating properties of these *** with that in intermetallic electrides,the orbital hybridization between the half-filled interstitial electrons and the surrounding atoms is weak,leading to highly localized magnetic centers and pronounced correlation ***,the Mott-insulating electrides Ae_(5)X_(3)have very large indirect bandgaps(0.30 eV).In addition,high pressure is found to strengthen the strong correlation effects and enlarge the *** present results provide a deeper understanding of the formation mechanism of Mott-insulating electrides and provide guidance for the search for new strongly correlated electrides.

关键词： intermetallic filled occupied

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Fine and ultrafine particle- and gas-polycyclic aromatic hydrocarbons affecting southern Thailand air quality during transboundary haze and potential health effects

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Journal of Environmental sciences 2023年第2期124卷 253-267页

作者： Napawan Mahasakpan Phatsarakorn Chaisongkaew Muanfun Inerb Nobchonnee Nim Worradorn Phairuang Surajit Tekasakul Masami Furuuchi Mitsuhiko Hata Thaniya Kaosol Perapong Tekasakul Racha Dejchanchaiwong Air Pollution and Health Effect Research Center Prince of Songkla UniversityHat YaiSongkhla 90110Thailand Energy Technology Program Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90110Thailand Faculty of Environmental Management Prince of Songkla UniversityHat YaiSongkhla 90110Thailand Department of Geography Faculty of Social SciencesChiang Mai UniversityMuangChiang Mai 50200Thailand Department of Chemistry Faculty of SciencePrince of Songkla UniversityHat YaiSongkhla 90110Thailand Faculty of Geoscience and Civil Engineering Institute of Science and EngineeringKanazawa UniversityKakuma-machiKanazawaIshikawa 920-1192Japan Department of Civil and Environmental Engineering Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90110Thailand Department of Mechanical and Mechatronics Engineering Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90110Thailand Department of Chemical Engineering Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90110Thailand

Distribution of PM_(0.1),PM_(1) and PM_(2.5) particle-and gas-polycyclic aromatic hydrocarbons(PAHs)during the 2019 normal,partial and strong haze periods at a background location in southern Thailand were investigated to understand the behaviors and carcinogenic ***1 was the predominant component,during partial and strong haze periods,accounting for 45.1% and 52.9% of total suspended particulate matter,respectively,while during normal period the contribution was only 34.0%.PM_(0.1) concentrations,during the strong haze period,were approximately 2 times higher than those during the normal *** increased levels of particle-PAHs for PM_(0.1),PM_(1) and PM_(2.5) were observed during strong haze period,about 3,5 and 6 times higher than those during normal ***-PAH concentrations were 10 to 36 times higher than those of particle-PAHs for PM_(2.5).Average total Benzo[a]Pyrene Toxic Equivalency Quotients(BaP-TEQ)in PM_(0.1),PM_(1) and PM_(2.5) during haze periodswere about 2–6 times higher than in the normal *** total accumulated Incremental Lifetime Cancer Risks(ILCRs)in PM_(0.1),PM_(1) and PM_(2.5) for all the age-specific groups during the haze effected scenario were approximately 1.5 times higher than those in nonhaze scenario,indicating a higher potential carcinogenic *** observations suggest PM_(0.1),PM_(1) and PM_(2.5) were the significant sources of carcinogenic aerosols and were significantly affected by transboundary haze from peatland *** leads to an increase in the volume of smoke aerosol,exerting a significant impact on air quality in southern Thailand,as well as many other countries in lower southeast Asia.

关键词： Particle-PAH Gas-PAH Ultrafine particle Health risk Source identification

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Oxidation State as a Descriptor in Oxygen Reduction Electrocatalysis

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CCS Chemistry 2022年第11期4卷 3587-3598页

作者： Ning Qin Sicen Yu Zongwei Ji Yanfang Wang Yingzhi Li Shuai Gu Qingmeng Gan Zhenyu Wang Zhiqiang Li Guangfu Luo Kaili Zhang Zhouguang Lu Department of Materials Science and Engineering Shenzhen Key Laboratory of Interfacial Science and Engineering of MaterialsSouthern University of Science and TechnologyShenzhen 518055 Department of Mechanical Engineering City University of Hong KongKowloonHong Kong 999077 Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and TechnologyShenzhen 518055

Electrocatalysts for the oxygen reduction reaction(ORR)are critically important in the development of fuel cells and metal-air *** research interests have been devoted to improving the electrocatalytic performance by tuning the morphology and defect-active ***,we demonstrate that the oxidation state can also serve as an effective strategy for designingORR *** of silver with gradient chemical valence from zero valence to trivalence were successfully *** oxidation states were evaluated by cryo-X-ray photoelectron spectroscopy,X-ray absorptionfinestructure,and electron paramagnetic resonance *** the first time,our results demonstrated that the electrocatalytic activities of silver species can be improved by increasing their valence,conforming the orderofAg

关键词： silver oxides high valence oxygen reduction oxidation state electrocatalysis

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Phase relations of the Ce2Co17-Sm2Co17pseudo-binary system

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International Journal of materials Research 2021年第5期111卷 373-378页

作者： Xu, Chengfu Gu, Zhengfei Yang, Yongquan Ma, Dongdong Cheng, Gang Yao, Qingrong Rao, Guanghui Zhang, Wenfeng Wang, Xian School of Mechanical Engineering Guilin University of Aerospace Technology Guilin Guangxi China School of Material Science and Engineering Guilin University of Electronic Technology Guilin Guangxi China

The phase relations in the Ce2Co17-Sm2Co17 system over the whole concentration range have been studied by means of X-ray powder diffraction, differential thermal analysis and scanning electron microscopy equipped with energy dispersive Xray spectroscopy. The X-ray powder diffraction results reveal that all the alloys (Ce1-xSmx)2Co17 are similar to the end member of the investigated system, Sm2Co17. It is implied that continuous solid solutions are formed in this system. The lattice parameters and unit cell volumes of (Ce1-xSmx)2Co17 solid solutions increase linearly with x increasing from 0 to 1.0. The occurrence of the polymorphic transformation reaction α-(Ce, Sm)2Co17 β-(Ce, Sm)2Co17 is confirmed in the Ce2Co17-Sm2Co17 system, but its transition temperature cannot be determined. The differential thermal analysis measurements show that both the decomposition temperature and the Curie temperature of the (Ce1-xSmx)2Co17 alloys increase gradually with increasing Sm content. Based on the X-ray powder diffraction results and differential thermal analysis data, the tentative vertical section of Ce2Co17-Sm2Co17 pseudobinary system has been constructed. © 2020 Carl Hanser Verlag, München.

关键词： X ray powder diffraction

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Negative thermal expansion in metamaterials made from 4D printed Cu–Al–Ni alloy

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Journal of materials Research and Technology 2025年 37卷 2005-2021页

作者： Daniyal Abolhasani Wook Jin Lee Young Hoon Moon Center for Innovative Technology on Advanced Forming School of Mechanical Engineering Pusan National University Busan 46241 Republic of Korea School of Material Science and Engineering Pusan National University Busan 46241 Republic of Korea

The materials used in precision instruments need to withstand temperature variations that causes dimensional variations due to thermal expansion (TE). To address this issue, mechanical metamaterials made from two materials with different TE have been proposed. However, fabricating such structures using additive manufacturing is challenging because it requires the simultaneous operation of two lasers or nozzles. Advanced materials, such as shape memory alloys (SMA)s, can achieve negative thermal expansion (NTE) through modifications in composition and microstructure, but their development is typically limited to single components. In pursuit of this objective, this study aims to provide valuable insights into the relationship between the shape memory effect (SME) and unit cells designed with straight (stretching-dominated) and curved (bending-dominated) beams at various angles between the beams (2β) ranging from 40° to 60°. The focus is on how these designs impact dimensional variations for NTE applications. NTE lattices made of high-temperature Cu–Al–Ni SMA were subjected to a thermal load of 400 K. The results indicated that larger angles in straight beams led to a softening effect, reducing the SME and size stability. In contrast, curved beams at larger angles demonstrated stable SME and maintained size stability due to the influence of bending moments and the reorientation of martensite. For beams at lower angles, heat radiation initially improved SME and size stability by promoting the reversion of remnant martensite back into austenite. However, the stress gradients in cells with curved beams at these angles resulted in twin disconnection, leading to decreased SME and size stability.

关键词： Metamaterial Negative thermal expansion Shape memory effect Cu–Al–Ni 4d printing

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Beyond Smoothness and Convexity: Optimization via Sampling

arXiv

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arXiv 2025年

作者： Seyoum, Nahom You, Haoxiang Department of Statistics and Data Science Yale University United States Department of Mechanical Engineering and Material Science Yale University United States

This work explores a novel perspective on solving nonconvex and nonsmoothoptimization problems by leveraging sampling based methods. Instead of treatingthe objective function purely through traditional (often deterministic)optimization approaches, we view it as inducing a target *** thendraw samples from this distribution using Markov Chain Monte Carlo (MCMC)techniques, particularly Langevin Dynamics (LD), to locate regions of lowfunction values. By analyzing the convergence properties of LD in both KLdivergence and total variation distance, we establish explicit bounds on howmany iterations are required for the induced distribution to approximate thetarget. We also provide probabilistic guarantees that an appropriately drawnsample will lie within a desired neighborhood of the global minimizer, evenwhen the objective is nonconvex or nonsmooth. © 2025, CC BY.

关键词： Markov chains

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Developing polydopamine modified molybdenum disulfide/epoxy resin powder coatings with enhanced anticorrosion performance and wear resistance on magnesium lithium alloys

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Journal of Magnesium and Alloys 2022年第9期10卷 2534-2545页

作者： Shibo Chen Changqing Yin Yi Wang Shuang Yi Xiang Gao Xujuan Zhang Qiyu Liao Yuxin Zhang Xia Zhao Jinsong Rao Baorong Hou School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004China College of Material Science and Engineering Chongqing UniversityChongqing 400044China Pilot National Laboratory for Marine Science and Technology Open Studio for Marine Corrosion and ProtectionQingdao 266237China Weifang East Steel Pipe Co.LTD. Weifang 261055China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China China Academy of Space Technology(Xi’an) Xi’an 710100China State Key Laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400044China

Epoxy resin powder coating has been successfully applied on the corrosion protection of magnesium lithium ***,poor wear resistance and microcracks formed during the solidification have limited it extensive *** are limited approaches to exploit such anti-corrosion and mechanical properties of magnesium lithium ***,the epoxy resin powder coating with polydopamine modified molybdenum disulfide(MoS_(2)@PDA-EP powder coating with 0,0.1,0.2,0.5,1.0 wt.%loading)was well prepared by melt extrusion to investigate its anticorrosion performance and wear *** results revealed that the addition of MoS_(2)@PDA enhanced the adhesion strength between coatings and alloys,wear resistance and corrosion protection of the powder *** them,the optimum was obtained by 0.2 wt.%MoS_(2)@PDA-EP powder coating which could be attributed to well dispersion and efficient adhesion with coating *** conclude,MoS_(2)@PDA-EP powder coating is meaningfully beneficial for the anticorrosive and wear performance improvement of magnesium lithium alloys.

关键词： Magnesium lithium alloys Epoxy resin powder coating Molybdenum disulfide Polydopamine Anticorrosion performance Wear resistance

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21-Component compositionally complex ceramics: Discovery of ultrahigh-entropy weberite and fergusonite phases and a pyrochlore–weberite transition

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Journal of Advanced Ceramics 2022年第4期11卷 641-655页

作者： Mingde QIN Heidy VEGA Dawei ZHANG Sarath ADAPA Andrew J.WRIGHT Renkun CHEN Jian LUO Department of Nano Engineering University of California San DiegoLa Jolla 92093USA Department of Chemistry and Biochemistry University of California San DiegoLa Jolla 92093USA Program of Materials Science and Engineering University of California San DiegoLa Jolla 92093USA Department of Mechanical and Aerospace Engineering University of California San DiegoLa Jolla 92093USA

Two new high-entropy ceramics(HECs)in the weberite and fergusonite structures,along with the unexpected formation of ordered pyrochlore phases with ultrahigh-entropy compositions and an abrupt pyrochlore–weberite transition,are discovered in a 21-component oxide *** the Gibbs phase rule allows 21 equilibrium phases,9 out of the 13 compositions examined possess single HEC phases(with ultrahigh ideal configurational entropies:~2.7kB per cation or higher on one sublattice in most cases).Notably,(15RE_(1/15))(Nb_(1/2)Ta_(1/2))O_(4) possess a single monoclinic fergusonite(C2/c)phase,and(15RE_(1/15))_(3)(Nb_(1/2)Ta_(1/2))_(1)O_(7) form a single orthorhombic(C222_(1))weberite phase,where 15RE_(1/15) represents Sc_(1/15)Y_(1/15)La_(1/15)Pr_(1/15)Nd_(1/15)Sm_(1/15)Eu_(1/15)Gd_(1/15)Tb_(1/15)Dy_(1/15)Ho_(1/15)Er_(1/15)Tm_(1/15) Yb_(1/15)Lu_(1/15).Moreover,a series of eight(15RE_(1/15))_(2+x)(Ti_(1/4)Zr_(1/4)Ce_(1/4)Hf_(1/4))_(2−2x)(Nb_(1/2)Ta_(1/2))_(x)O_(7) specimens all exhibit single phases,where a pyrochlore–weberite transition occurs within 0.75

关键词： compositionally complex ceramics high-entropy ceramics(HECs) weberite pyrochlore fergusonite ultrahigh-entropy ceramics many-component ceramics

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