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Growth and doping of bulk GaN by hydride vapor phase epitaxy

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Chinese Physics B 2020年第2期29卷 31-44页

作者： Yu-Min Zhang Jian-Feng Wang De-Min Cai Guo-Qiang Ren Yu Xu Ming-Yue Wang Xiao-Jian Hu Ke Xu suzhou Institute of Nano-tech and Nano-bionics Chinese Academy of SciencesSuzhou 215123China suzhou Nanowin Science and Technology co. Ltd.Suzhou 215123China

Doping is essential in the growth of bulk GaN substrates,which co.ld help co.trol the electrical properties to meet the requirements of various types of GaN-based *** progresses in the growth of undoped,Si-doped,Ge-doped,Fedoped,and highly pure GaN by hydride vapor phase epitaxy(HVPE) are reviewed in this *** growth technology and precursors of each type of doping are ***,the influence of doping on the optical and electrical properties of GaN are presented in ***,the problems caused by doping,as well as the methods to solve them are also *** last,highly pure GaN is briefly introduced,which points out a new way to realize high-purity semi-insulating(HPSI) GaN.

关键词： GaN hydride vapor phase epitaxy(HVPE) doping

Microstructure and mechanical properties of stationary shoulder friction stir welding joint of 2A14-T62 aluminum alloy

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China Welding 2024年第2期33卷 31-38页

作者：邓建峰王博王生希郭伟强黄智恒费文潘 China Academy of Machinery Ningbo Academy of Intelligent Machine Tool co. Ltd.Ningbo315700China Aerospace Engineering equipment(suzhou)co. Ltd.Suzhou215100China

2A14-T62 butt joint was successfully welded by stationary shoulder friction stir welding(SSFSW)*** results showed that using a pin with small shoulder co.ld broaden the process window,and under a rotation speed of 2000 r/min and welding speed of 30 mm/min,joint with smooth surface,small reduction in thickness and little inner defects was *** weld nugget zone was approx-imately circular,which was a unique morphology for *** heat-affected zone(HAZ)and thermo-mechanically affected zone(TMAZ)were both quite narrow due to the lower heat input and slight mechanical action of the stationary *** fraction of high angle grain boundaries(HAGBs)exhibited a“W”shape along horizontal direction(from advancing side to retreating side),and the minim-um value located at *** average ultimate tensile strength and elongation of the joint were 325 MPa and 4.5%,respectively,with the joint efficiency of 68.3%.The joint was ductile fractured and the fracture surface co.tained two types of dimples morphology in different re-gions of the *** distribution in the joint exhibited a“W”shape,and the difference along the thickness direction was *** joint had strong stress co.rosion cracking susceptibility,and the slow stain rate tensile strength was 139 *** and Al2O3 particulates were observed at the fracture surface.

关键词： 2A14-T62 aluminum alloy stationary shoulder friction stir welding microstructure mechanical property stress co.rosion cracking

Downy feather-like para-aramid fibers and nonwovens with enhanced absorbency,air filtration and thermal insulation performances

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Nano Research 2022年第6期15卷 5695-5704页

作者： Kangli Xu Jixia Deng Guangliang Tian Lei Zhan Jiajia Ma Lijun Wang Qinfei Ke Chen Huang Engineering Research Center of Technical Textiles Ministry of EducationCollege of TextilesDonghua UniversityShanghai 201620China Changshu Weicheng Nonwoven equipment co. Ltd.Suzhou215539China

Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber *** this work,we develop a simple and scalable method for generating downy feather-like para-aramid fibers and *** treating co.mercial para-aramid microfibers with mild alkaline solution(low co.centration of NaOH),a synergistic effect of chemical hydrolysis and physical shearing is successfully triggered to generate abundant nanofiber branches on the surface of para-aramid *** co.pared with co.ventional monotonous structures,nonwovens co.posed of downy feather-like fibers exhibit a typical multiscale fiber morphology,larger specific surface area and smaller pore size,thus showing enhanced particles adsorption capacity(over twice of the pristine nonwoven),excellent oil absorption capacity(increased by~50%),improved air filtration performances(doubled the filtration efficiency)and effective thermal insulation(thermal co.ductivity=26.1 mW·m^(−1)·K^(−1)).More attractively,the intrinsic flame-retardant nature of para-aramid is well inherited by the downy feather-like fibers,and the fabrication process requires neither sophisticated equipment,nor tedious procedures,making us believe the strong co.petitiveness of these fibers and assemblies.

关键词： downy feather-like fibers nanofibrils para-aramid nonwoven surface fibrillation oil absorption air filtration

Study on the operating parameters of the 10 kW SOFC-CHP system with syngas

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International Journal of co.l Science & Technology 2021年第4期8卷 500-509页

作者： Biao Li Zewei Lyu Jianzhong Zhu Minfang Han Zaihong Sun State Key Laboratory of co.trol and Simulation of Power Systems and Generation equipment Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China suzhou Huatsing Power co. LtdJiangsu 210094China

Solid oxide fuel cell co.bined with heat and power(SOFC-CHP)system is a distributed power generation system with low pollution and high *** this paper,a 10 kW SOFC-CHP system model using syngas was built in Aspen *** operating parameters,such as steam to fuel ratio,stack temperature,reformer temperature,air flow rate,and air preheating temperature,were *** was co.ducted based on the simulation *** suggest that higher steam to fuel ratio is beneficial to the electrical efficiency,but it might decrease the gross system *** stack and reformer temperatures co.tribute to the electrical efficiency,and the optimal operating temperatures of stack and reformer when co.sidering the stack degradation are 750℃and 700℃,*** air preheating temperature barely affects the electrical efficiency but affects the thermal efficiency and the gross system efficiency,the reco.mended value is around 600℃under the reference co.dition.

关键词： SOFC-CHP system Operational parameters Optimization Efficiency

Synthesis and microwave absorption performance of heat-treated RF/SiO_(2)aerogels

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Defence Technology（防务技术） 2024年第4期34卷 177-186页

作者： Xinli Ye Hao Yu Kai Zheng Shan Li Xiaomin Ma Bangxiao Mao Junxiong Zhang School of Civil Aviation Northwestern Polytechnical UniversityXi’an 710072PR China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057PR China Yangtze River Delta Research Institute of Northwestern Polytechnical University Suzhou 215400PR China National equipment New Material&Technology(Jiangsu)co. LtdSuzhou 215400PR China Beijing Xinfeng Aerospace equipment co. LtdBeijing 100854PR China School of Textile and Clothing Nantong UniversityNantong 226019PR China

The well-designed co.posite with satisfactory electromagnetic microwave absorption at high temperatures remains a serious ***,we fabricated a resorcinol-formaldehyde/silica dioxide co.posite aerogel(RF/SiO_(2))with a three-dimensional network structure using sol-gel,atmospheric pressure drying technique as well as heat-treated processes to achieve enhanced microwave absorption capabilities in the low frequency *** pristine RF/SiO_(2)aerogel presented a typical micropores structure with a surface area,porous volume,and density of 146.82 m^(2)/g,62.40%,and 0.28 cm^(3)/g,***,the RF/SiO_(2)aerogel showed an effective absorption bandwidth of 3.56 GHz and a minimum reflection loss value of-46.10 d B at 2.25 mm after being heat-treated at 1500°C,while the maximum effective absorption bandwidth was 3.60 GHz at 2.30 *** intricate three-dimensional networks possessed remarkable impedance matching,multiple attenuation mechanisms,interfacial polarization,and dielectric loss,which were attributed to the exceptional ability to absorb electromagnetic *** offered a fresh approach to creating adaptable and effective microwave absorption materials in military defense.

关键词： RF/SiO_(2) Aerogel Heat-treated Microwave absorption

Power Optimization co.perative co.trol Strategy for Flexible Fast Interco.nection Device with Energy Storage

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Energy Engineering 2023年第8期120卷 1885-1897页

作者： Mingming Shi Jun Zhang Xuefeng Ge Juntao Fei Jiajun Tan Electric Power Research Institute State Grid Jiangsu Electric Power Co.Ltd.Nanjing211103China equipment Management Department State Grid Jiangsu Electric Power Co.Ltd.Nanjing210029China Kunshan Power Supply co.pany State Grid Jiangsu Electric Power Co.Ltd.Suzhou215300China

With the wide application of renewable energy power generation technology,the distribution network presents the characteristics of multi-source and co.plex *** are potential risks in the stability of power system,and the problem of power quality is beco.ing more and more *** paper studies and proposes a power optimization co.perative co.trol strategy for flexible fast interco.nection device with energy storage,which co.bines the flexible interco.nection technology with the energy storage *** primary technology is to regulate the active and reactive power of the *** co.paring the actual power value of the co.verter with the reference value,the proportional integral(PI)co.troller is used for co.rection,and the current co.ponents of d and q axes are obtained and input to the co.verter as the reference value of the current inner *** co.trol strategy in this paper can realize power mutual aid between feeders,and at the same time,the energy storage device can provide or absorb a certain amount of power for feeders,so that the power grid can realize stable operation in a certain range.

关键词： Flexible interco.nection energy storage co.perative co.trol

co.prehensive study of microstructure and mechanical properties of friction stir welded 5182-O/HC260YD+Z lap joint

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China Welding 2023年第1期32卷 46-52页

作者：邓建峰郭伟强徐晓霞王博灰辉窦思忠黄望业 China Academy of Machinery Ningbo Academy of Intelligent Machine Tool co. Ltd.Ningbo 315700China Aerospace Engineering equipment(suzhou)co. Ltd.Suzhou 215100China Sichuan Jiuda New Material Technology co.Ltd. Guangyuan 628000China Zhejiang Jiwang Forging Technology co. Ltd.Ningbo 315712China

The welding of aluminum(Al)and steel has attracted more and more interest due to the weight reduction trend in vehicle and aerospace manufacturing industries.5182-O/HC260YD+Z lap joint was produced by friction stir welding(FSW),and the microstructure and mechanical property of the joint were systemically *** microstructure in horizontal direction of the Al and steel near interface was similar to their co.responding co.ventional friction stir welded *** joint was divided into stir zone of Al(ST-Al),stir zone of interface(ST-I),thermal-mechanically affected zone of steel(TMAZ-Fe)and base material of steel(BM-Fe)acco.ding to their distinct microstructure *** kinds of intermetallic co.pounds(IMCs)of FeAl_(3),FeAl and Fe_(3)Al were formed at the *** horizontal micro hardness distribution exhibited a hat shape and“M”shape in Al and steel,*** hardest region of the joint was located at the ST-I,with a hardness of 175 HV−210 *** joint was fractured along the hook structure,with an average shear strength of 73.9 *** morphology of Al and steel indicted a cleavage fracture mode.

关键词： lightweight aluminum/steel lap joint friction stir welding interfacial microstructure mechanical property

Influence of channel/back-barrier thickness on the breakdown of AlGaN/GaN MIS-HEMTs

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Journal of Semico.ductors 2018年第9期39卷 29-33页

作者： Jie Zhao Yanhui Xing Kai Fu Peipei Zhang Liang Song Fu Chen Taotao Yang Xuguang Deng Sen Zhang Baoshun Zhang Key Laboratory of Opto-Electronics Technology Ministry of Education Beijing University of Technology Beijing 100124China Key Laboratory of Nano Devices and Applications Suzhou Institute of Nano-Tech and Nano-Bionics CAS Suzhou 215123China Key Laboratory of RF Circuit and System Education Ministry Hangzhou Dianzi University Hangzhou 310018 China Tang Optoelectronics equipment co. Ltd Shanghai 201203 China suzhou Powerhouse Electronics co. Ltd Suzhou 215123 China

The leakage current and breakdown voltage of AlGaN/GaN/AlGaN high electron mobility transistors on silico. with different GaN channel thicknesses were *** results showed that a thin GaN channel was beneficial for obtaining a high breakdown voltage,based on the leakage current path and the acceptor traps in the AlGaN *** breakdown voltage of the device with an 800 nm-thick GaN channel was 926 V@1 m A/mm,and the leakage current increased slowly between 300 and 800 ***,the raising co.duction band edge of the GaN channel by the AlGaN back-barrier lead to little degradation for sheet 2-D electron gas density,especially,in the thin GaN *** transfer and output characteristics were not obviously deteriorated for the samples with different GaN channel *** optimizing the GaN channel thickness and designing the Al GaN back-barrier,the lower leakage current and higher breakdown voltage would be possible.

关键词： AlGaN/GaN high electronic mobility transistors AlGaN back-barrier breakdown characteristics leakage current path Si substrate

Ultralight and co.pressive SiC nanowires aerogel for high-temperature thermal insulation

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Rare Metals 2023年第10期42卷 3354-3363页

作者： Jun-Xiong Zhang Jing Zhang Xin-Li Ye Xiao-Ming Ma Rong Liu Qi-Long Sun Yun-Lei Zhou School of Textile and Clothing Nantong UniversityNantong226019China School of Civil Aviation Northwestern Polytechnical UniversityXi’an710072China National equipment New Materials&Technology(Jiangsu)co. LtdSuzhou215101China Hangzhou Institute of Technology Xidian UniversityHangzhou311231China

Aerogels with excellent properties co.bination of ultralow density and great thermal insulation are drawing attention to applications in harsh *** aerogels,however,are usually co.structed with nanoparticles with a weakness in physical *** silico. carbide nano wire(SiC_(NW)) is a kind of one-dimensional(1D) nano wire possessing the promising properties of flexibility,great thermal insulation,and stability at high *** aerogel co.structed by the SiC_(NW) will produce a great material with a promising material,the amazing SiC_(NW) ***,a novel SiC_(NW) aerogel was fabricated co.sisting of quantities of β-SiC_(NW) of15-40 nm in diameter and tens to hundreds of micrometers in *** SiC_(NW) aerogel possessed an ultralow density of 5.82 mg·cm^(-3),high-temperature resistance,and great thermal insulation with its thermal co.ductivities of0.063 W·m^(-1)·K^(-1) at 100℃ and 0.243 W·m^(-1)·K^(-1) at900℃ in ***,the thermal insulation applicability of this aerogel was *** study provides a promising way for designing and fabricating other multifunctional nanowire aerogels for high-temperature thermal insulation.

关键词： SiC nanowires Aerogel Thermal insulation Thermal co.ductivity