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Rare Metals 2006年第z1期25卷 557-561页

作者： YANG Qinghui zhang huaiwu LIU Yingli School of Micro-Electronic University of Electronic Science and Technology of China Chengdu 610054 China School of Micro-Electronic University of Electronic Science and Technology of China Chengdu 610054 China School of Micro-Electronic University of Electronic Science and Technology of China Chengdu 610054 China

The magnetic and magneto-optical properties of heavily doped Bi∶YIG film were studied. The film was deposited by radio frequency magnetron sputtering method and crystallized by rapid recurrent thermal annealing (RRTA). The results show that the RRTA treated film has good properties both in microwave and optical wave band. The saturation magnetization of the film on different substrates varies from 135.7 to 138.6 kA·m-1. The coercive field of the film on GGG substrate is about 0.32 kA·m-1, while about 0.8-1.43 kA·m-1 on YAG substrate and 1.75 kA·m-1 on Al2O3 substrate. The Faraday angle is about 3-5 (°)·μm-1 when optical wavelength ranges at 450-600 nm. The transmission spectra of the Bi∶YIG films on three substrates has similar change as annealing temperature below 800 ℃. Specially, when annealing temperature is above 800 ℃ a step is observed between 550 and 650 nm wavelength for the film deposited on Al2O3 *** results are very useful in magneto-optical recording application and integrated microwave devices.

关键词： magneto-optical effect rapid recurrent thermal annealing (RRTA) Faraday effect radio frequency magnetron sputtering

Low-temperature sintering and microwave dielectric properties of CaMg1−xLi2xSi2O6(x=0−0.3)ceramics

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Journal of Advanced Ceramics 2020年第4期9卷 471-480页

作者： Fangyi Huang Hua Su Yuanxun Li huaiwu zhang Xiaoli Tang State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China Jiangxi Guo Chuang Industrial Park Development Co. Ltd.Ganzhou341000China

In this study, low-temperature fired CaMg1−xLi2xSi2O6 microwave dielectric ceramics were prepared via the traditional solid-state reaction method. In this process, 0.4 wt% Li2CO3-B2O3-SiO2-CaCO3-Al2O3 (LBSCA) glass was added as a sintering aid. The results showed that ceramics consisted of CaMgSi2O6 as the main phase. The second phases were CaSiO3 always existing and Li2SiO3 occurring at substitution content x > 0.05. Li+ substitution effectively lowered sintering temperature due to 0.4 wt% LBSCA and contributed to grain densification, and the most homogeneous morphology could be observed at x = 0.05. The effects of relative density, the second phase, and ionic polarizability on dielectric constant (εr) were investigated. The quality factor (Q × f) varied with packing fraction that concerned the second phase. Moreover, the temperature coefficient of the resonant frequency (τf) was influenced by MgO6 octahedral distortion and bond valence. Excellent dielectric properties of the CaMg1−xLi2xSi2O6 ceramic was exhibited at x = 0.05 with εr = 7.44, Q × f = 41,017 GHz (f = 15.1638 GHz), and τf = −59.3 ppm/°C when sintered at 900 °C. It had a good application prospect in the field of low-temperature co-fired ceramic (LTCC) substrate and devices.

关键词： low permittivity low-temperature sintering crystal structure microwave dielectric properties

Investigation of Antimony ions doping on crystal structure and enhanced microwave dielectric performance of MgTa_(2)O_(6)ceramics

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Journal of Materiomics 2023年第4期9卷 701-708页

作者： Liang Shi Kui Liu Cheng Liu Dainan zhang huaiwu zhang School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu610054China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

Dielectric ceramics are promising in large-scale commercial millimeter-wave communication technology,such as 5G and the upcoming 6G,thanks to their excellent frequency selection characteristics and environmental *** this work,various contents of SbeO bonds were introduced into the MgTa_(2)O_(6)lattice using the solid-phase reaction method to investigate the effects on the lattice and microwave dielectric *** confirms that Sb ions successfully occupy Ta sites in the lattice and cause lattice shrinkage and crystallinity deterioration,which leads to a slight decrease in the quality ***,DFT calculations reveal that the doping leads to electron-biased aggregation toward O atoms,causing higher SbeO ionicity,but also attenuates the degree of ionization of Ta and Mg ions,which makes the dielectric constant of the doped samples vary non-monotonically with gradient ***,Sb doping substantially enhanced the thermal stability of the ceramics,with TCF values reduced from 36×10^(-6)℃^(-1)to 15×10^(-6)℃^(-1).

关键词： MgTa_(2)O_(6)ceramics Dielectric Raman DFT calculation

Characterization of sputtering CoFe-ITO junction for spin injection

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Rare Metals 2006年第z1期25卷 536-539页

作者： WEN Qiye SONG Yuanqiang YANG Qinghui zhang huaiwu Key Laboratory of Electronic Film and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China

The combination of ferromagnetic metal(FM)and semiconductor(SC)for spin injection was studied and demonstrated with FM-SC-FM *** semiconductor was chosen to be doped Indium-Tin-Oxide(ITO).Both ITO single-layer film and CoFe-ITO-CoFe junction were sputtering *** ITO single-layer film was n-type with a small resistance of about 100Ω/Square.I-V curves and Magnetoresistance(MR)effect of the CoFe-ITO-CoFe junction were measured at room temperature and 77 *** show that the CoFe forms an ohmic contact to ITO *** at low temperature,the I-V curves show a Schottky-like characteristic,which is strongly affect by applied magnetic *** MR effect was measured to be 1%at 77 K,which indicates a spin injection into semiconductor to be realized in this sandwich junction.

关键词： ferromagnetic semiconductor junction I-V characteristic magnetoresistance spin injection

Design and application of active sites in g-C_(3)N_(4)-based photocatalysts

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Journal of Materials Science & Technology 2020年第21期56卷 69-88页

作者： Yang Li Xin Li huaiwu zhang Jiajie Fan Quanjun Xiang State Key Laboratory of Electronic Thin Film and Integrated Devices School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu610054China College of Resources and Environment Huazhong Agricultural UniversityWuhan430070China College of Forestry and Landscape Architecture Key Laboratory of Energy Plants Resource and UtilizationMinistry of AgricultureKey Laboratory of Biomass Energy of Guangdong Regular Higher Education InstitutionsSouth China Agricultural UniversityGuangzhou510642China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450002China

With the development in photocatalysis field,photocatalysts have received increasing attention due to their important role in environmental pollution and energy *** a nonmetallic photocatalyst,graphitic carbon nitride(g-C3N4)has been widely recognized because of its excellent optical properties,low cost,and environment *** the g-C3N4 intrinsic frameworks,carbon atom tends to be the reducing active site,while nitrogen atom tends to be the oxidizing active site and reducing active site according to the difference of ***,the quantity and quality of these active sites are affected by many factors,including C N covalent bonds,surface properties,*** sites play an important role in photocatalysis;however,this role is not detailed in most *** this review,we proposed the following possible mechanisms of active sites in improving the photocatalytic activity of traditional g-C_(3)N_(4) based on its intrinsic:morphology regulation,carrier migration,surface active treatment,and substrate *** following factors affecting the active sites of g-C_(3)N_(4),including basal engineering and hybrid engineering,were also *** roles of these active sites in improving the photocatalytic activity of g-C_(3)N_(4)-based photocatalytic materials,including morphology regulation,surface treatment,heteroatom doping,and interfacial interaction,were also *** challenges and future development of g-C_(3)N_(4)-based photocatalysts that are rich in active surface sites were also *** review provides an in-depth understanding of g-C_(3)N_(4)-based photocatalysts.

关键词： Graphitic carbon nitride Active sites Photocatalyst Solar fuels

Nucleation field,reversal mechanism and coercivity paradox in two-phased magnetic nanosystem

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Science China(Physics,Mechanics & Astronomy) 2011年第7期54卷 1249-1253页

作者： ZHAO GuoPing zhang huaiwu ZHONG ZhiYong CHEN Lang College of Physics and Electronic Engineering Sichuan Normal University Chengdu 610066 China State Key Laboratory of Electronic Thin Films and lntegrated Devices University of Electronic Science and Technology of China Chengdu 610054 China School of Materials Science and Engineering Nanyang Technological University Singapore 639798 Singapore

The magnetic reversal mechanism has been determined within a micromagnetic model reliably for a two-phased magnetic nanosystem, with the formulae for nucleation fields derived analytically. It is found that the nucleation field HN decreases uni- formly as the size of the soft phase Ls increases whereas it increases with the size of the hard phase Lh. The analysis shows that whilst the effect of Lh could be ignored in most cases, where the nucleation field is dominated by the Ls and the calculation could be significantly simplified, the overly simple inverse square law between Hu and the soft layer thickness Ls adopted by the previous researchers is not a good approximation. While nucleation is the beginning of the magnetic reversal, pinning is the dominant coercivity mechanism in both two-phased and single-phased magnetic materials, where the crystalline defects exist. Comparison with the experimental data confirms this conclusion, indicating that Brown＇s paradox results from the much lower effective anisotropy in both single-phased and composite materials, as speculated in the literature.

关键词： coercivity mechanism multilayers micromagnetic calculation

Bond, vibration and microwave dielectric characteristics of Zn_(1- x)(Li_(0.5)Bi_(0.5))_(x)WO_(4) ceramics with low temperature sintering

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Journal of Materiomics 2022年第2期8卷 392-400页

作者： Qin zhang Hua Su huaiwu zhang Xiaoli Tang State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China Yangtze River Delta Research Institute of UESTC(Huzhou) Huzhou313000China

The bond,vibration and microwave dielectric characteristics of Zn_(1- x)(Li_(0.5)Bi_(0.5))_(x)WO_(4)(x=0-0.12)ce-ramics were investigated by XRD refinement,Raman and FT-IR spectroscopy and complex bond valence *** results showed that proper substitution of(Li_(0.5)Bi_(0.5))2þcan improve the sintering charac-teristics and microwave dielectric properties of ZnWO_(4).The increase of Q×f value was mainly attributed to dense and uniform microstructure,and the subsequent decrease resulted from the deterioration of structural stability and relative *** to the complex bond valence theory,the chemical bond characteristics of ZnWO_(4) and Bi_(2)WO_(6) played an important role in the dielectric properties of the ***,the samples(x=0.02)sintered at 900℃ showed satisfactory properties:ε_(r)=15.332,Q×f=35,762 GHz,and t_(f)=-65 ppm/℃,making it a potential candidate material for LTCC applications.

关键词： Zn_(1-x)(Li_(0.5)Bi_(0.5))_(x)WO_(4) Complex bond valence theory Raman and FT-IR spectroscopy Microwave dielectric properties

Relationship between structure and properties of microwave dielectric ceramic Li_((1+x))2MgTi3O8 based on Li non-stoichiometry

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Journal of Materiomics 2023年第2期9卷 279-288页

作者： Kui Liu Cheng Liu Jie Li Lichuan Jin huaiwu zhang School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu610054China State Key Laboratory of Electronic Thin Film and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

Li(_(1+x))2MgTi3O8(0.0≤x≤0.10)ceramics with Li non-stoichiometric ratios were prepared by the solidstate reaction method to inhibit the volatilization of *** effects of the Li non-stoichiometric ratios on the sintering behavior,crystal structure,microscopic morphology,Raman vibrations,electron density,and dielectric properties of Li(_(1+x))2MgTi3O8 ceramics were systematically *** Li(1+0.06)_(2)MgTi_(3)O_(8)ceramics demonstrate the best dielectric properties withεr=26.33,Q×f=69435 GHz(@6.87 GHz,54%improvement),tf=2.95×10^(-6)℃^(-1).For the non-intrinsic factors,the high relative density(97.15%)and larger grain size(16.78 mm)allow the dielectric properties to be *** for the intrinsic factors,a reasonable excess of Li improves the bond ionicity of the MgdO bond,the lattice energy of the TidO bond,and the electron cloud density,thus optimizing the dielectric *** spectroscopy leads to the same result from the point of view of lattice *** the same time,the distortion of the polyhedra is also improved,so that tf also approaches *** improved Li(1+0.06)2MgTi3O8 has potential applications in microwave communication technology.

关键词： Li(1+x)_(2)MgTi_(3)O_(8) Raman vibration First-principles P-V-L theory Microwave dielectric

Molecular-beam epitaxy-grown HgCdTe infrared detector:Material physics, structure design, and device fabrication

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Science China(Physics,Mechanics & Astronomy) 2023年第3期66卷 32-57页

作者： Xiaohui Wang Mengbo Wang Yulong Liao huaiwu zhang Baohui zhang Tianlong Wen Jiabao Yi Liang Qiao State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 611731China Yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou 313001China Kunming Institute of Physics Kunming 650223China Global Innovative Centre for Advanced Nanomaterials School of EngineeringThe University of NewcastleCallaghan NSW 2308Australia School of Physics University of Electronic Science and Technology of ChinaChengdu 611731China

Infrared(IR) detectors have important applications in numerous civil and military sectors. Hg Cd Te is one of the most important materials for IR detector manufacture. This review systematically discusses the progress of Hg Cd Te materials grown via molecular-beam epitaxy(MBE) for IR detection in terms of material physics, structure design, and fabrication. The material physics of Hg Cd Te includes crystal information, band structure, and electrical and optical properties. The characterization methods of the As-grown Hg Cd Te materials are also summarized. Then, four design structures of Hg Cd Te for IR detectors, with multilayer, superlattice, double-layer heterojunction, and barrier properties, which significantly improve the device performance,are discussed. The third section summarizes the studies on Hg Cd Te MBE-grown on different substrates, including Cd Zn Te, Si,and Ga Sb, in recent decades. This review discusses the factors influencing the growth of the Hg Cd Te film and their relationships and optimal conditions. Finally, we present the prospects and challenges associated with the fabrication and applications of Hg Cd Te materials for IR detectors.

关键词： HgCdTe infrared detector MBE etch pit density

Characterization of the charge transport and electrical properties in solution-processed semiconducting polymers

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Science China(Physics,Mechanics & Astronomy) 2012年第5期55卷 786-791页

作者： WANG LiGuo zhang huaiwu TANG XiaoLi LI YuanXun ZHONG ZhiYong State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China

The conventional charge transport models based on density- and field-dependent mobility, only having a non-Arrhenius tem- perature dependence, cannot give good current-voltage characteristics of poly （2-methoxy-5-（2＇-ethylhexyloxy）-p-phenylene vinylene）（MEH-PPV） hole-only devices. In this paper, we demonstrate that the current-voltage characteristics can give a good unified description of the temperature, carrier density mad electric field dependence of mobility based on both the Arrhenius temperature dependence and the non-Arrhenius temperature dependence. Fu^hermore, we perform a systematic study of charge transport and electrical properties for MEH-PPV. It is shown that the boundary carrier density has an important effect on the current-voltage characteristics. Too large or too small values of boundary carrier density will lead to incorrect cur- rent-voltage characteristics. The numerically calculated carrier density is a decreasing function of the distance to the interface, and the numerically calculated electric field is an increasing function of the distance. Both the maximum of carrier density and the minimum of electric field appear near the interface.

关键词： charge transport electrical properties semiconducting polymers