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Influence of thickness on strain state and surface morphology of AlN grown by HVPE

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Journal of Semiconductors 2016年第12期37卷 18-21页

作者：孙茂松张纪才黄俊李雪威王林军刘雪华王建峰徐科 School of Materials Science and Engineering Shanghai University platform for characterization and test Suzhou Institute of Nano-Tech and Nano-BionicsCAS Suzhou Nanowin Science and Technology Co Ltd

AIN thick films were grown on c-plane sapphire substrates by hydride vapor phase epitaxy at high temperature. The evolution of the strain state and crystal quality of AIN with increase of thickness were investigated by transmission electron microscopy, field-emission scanning electron microscopy, Raman spectra and atomic force microscopy （AFM）. As the thickness increased, the stress in the epilayers decreased gradually, which was attributed to the reaction of dislocations at the first several microns in thickness. When the thickness was more than 20 μm, the stress was almost fully relaxed due to the formation of cracks. Wet etching experiments indicated that the dislocation density decreased with the increase of thickness. The AFM images showed that the density of dark spots on the surface obviously decreased and the atomic steps became straight as the thickness increased.

关键词： AIN HVPE surface morphology strain state

Microstructural Stability of a Single Crystal Superalloy DD8 during Thermal Exposure

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Journal of Materials Science & Technology 2008年第1期24卷 127-130页

作者： K.Y.Cheng D.H.Kim Y.S.Yoo C.Y.Jo T.Jin Z.Q.Hu SuperalloyDivision Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China High Temperature Materials Group KIMS Changwon Korea Materials test and characterization Group KIMS Changwon Korea

Microstructural stability of a nickel base single crystal alloy DD8 has been *** heat treated specimen showed good microstructural stability at 950℃.While under the as-cast condition,a kind of rod-like phase precipitated in the interdendritic region of as-cast specimen during thermal *** phase,which has bcc structure,was enriched with ***-calc also predicted precipitation of a bcc phase at around 950℃.The Cr-rich bcc phase was considered asα-Cr and formed due to the segregation of Cr under the as-cast condition.

关键词： DD-8 Single crystal alloy Microstructural stability Alpha chromium

Effect of annealing temperature on Ti/Al/Ni/Au ohmic contacts on undoped AlN films

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Journal of Semiconductors 2017年第11期38卷 109-112页

作者： Xuewei Li Jicai Zhang Maosong Sun Binbin Ye Jun Huang Zhenyi Xu Wenxiu Dong Jianfeng Wang Ke Xu platform for characterization and test Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou 215123 China Suzhou Nanowin Science and Technology Co. Ltd Suzhou 215123 China University of Chinese Academy of Sciences Beijing 100049 China

The Ti/Al/Ni/Au metals were deposited on undoped AlN films by electron beam evaporation. The influence of annealing temperature on the properties of contacts was investigated. When the annealing temperatures were between 800 and 950 ℃, the AlN-Ti/Al/Ni/Au contacts became ohmic contacts and the resistance decreased with the increase of annealing temperature. A lowest specific contacts resistance of 0.379 Ω·cm^2 was obtained for the sample annealed at 950 ℃. In this work, we confirmed that the formation mechanism of ohmic contacts on Al N was due to the formation of Al-Au, Au-Ti and Al-Ni alloys, and reduction of the specific contacts resistance could originate from the formation of Au2Ti and AlAu2 alloys. This result provided a possibility for the preparation of Al N-based high-frequency, high-power devices and deep ultraviolet devices.

关键词： ohmic contacts AlN annealing temperature Ti/Al/Ni/Au

VNIR image simulation based on low-level flight image data

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Chinese Optics Letters 2010年第4期8卷 345-347页

作者：张冬英易维宁洪津杜丽丽方薇乔延利 Key Laboratory of Optical Calibration and characterization Chinese Academy of Sciences Information Department Artillery Academy of PLA Key Laboratory of Optical Calibration and characterization Chinese Academy of Sciences Institute of Intelligent Machines Chinese Academy of Sciences Key Laboratory of Optical Calibration and characterization

A simulation method for visible and near infrared（VNIR） image is *** VNIR image obtained by low-level flight is adopted as data *** atmospheric correction,the ground reflectivity can be *** simulation method consists of four steps：radiative transfer,spatial resolution,modulation transfer function,and noise *** image of satellite-borne or high-level air-borne sensor could be generated by the simulation method from VNIR *** is carried out to test the method using an airship as *** resulting simulated image is compared to the image with quickbird panchromatic *** result shows that simulation images enables one to effectively reproduce the entire process of remote sensing of the *** method can be used to simulate VNIR image at satellite level at the same area and the same wavelength.

关键词： Remote sensing

Synthesis of ZrC Nanoparticles in the ZrO_2–Mg–C–Fe System Through Mechanically Activated Self-Propagating High-Temperature Synthesis

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Acta Metallurgica Sinica(English Letters) 2014年第6期27卷 1144-1151页

作者： Abdollah Hajalilou Mansor Hashim Halimah Mohamed kamari Kazem Javadi Samikannu Kanagesan Mohammad Parastegari Materials Synthesis and characterization Laboratory Institute of Advanced Technology (ITMA) University Putra Malaysia Physics Department University Putra Malaysia Irankhodrow Industry Mechanical Testing Laboratory Materials Synthesis and characterization Laboratory Isfahan University of Technology

ZrC nanoparticles in the matrix of Fe were produced by the mechanically activated self-propagating hightemperature method using ZrO2/C/Mg/Fe powder mixtures. The effects of milling time, Fe content, and combustion temperature as well as the formation route for synthesizing ZrC powder particles were studied. The samples were characterized by XRD, SEM, TEM, and DTA. The XRD results revealed that, after 18 h of mechanical activation, ZrO2/ZC/Mg/Fe reacted with the self-propagating combustion（SHS） mode at 870 °C producing the ZrC–Fe nanocomposite. It was also found that both mechanical activation and Fe content played key roles in the ZrC synthesis temperature. With a Fe content of（5–40） wt%, the SHS reaction proceeded favorably and both the ZrC formation temperature and the adiabatic temperature（Tad） decreased. The Mg O content was removed from the final products using a leaching test process by dissolving in hydrochloric and acetic acids.

关键词： Mechanical activation(MA) Combustion synthesis Fe–ZrC composite Leaching process

Hydrothermal Synthesis and characterization of Nd Doped One-dimensional Hexagonal CePO_4 Nanowires

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Chinese Journal of Structural Chemistry 2012年第5期31卷 718-722页

作者：张新奇 test Center Fuzhou University

One-dimensional Nd doped CePO4 hexagonal nanowires have been synthesized for the first time at 140 ℃ for 24 hours via a hydrothermal method using P123 surfactant as the *** products were characterized by X-ray diffraction,transmission electron microscopy,photoluminescence and high-resolution transmission electron *** with CePO4,one-dimensional nanomaterials we have synthesized,Nd doped CePO4 nanomaterials remain their hexagonal one-dimensional morphology and smooth ***,their photoluminescence emissions are greatly enhanced at the wavelength of 348 *** their novel fluorescence-emission property,the Nd doped CePO4 nanomaterials are potential in many fields such as optics and electronics.

关键词： hydrothermal crystal growth one-dimensional structures P123 surfactant Nd dopant

Ultrahigh-performance planar β-Ga2O3 solar-blind Schottky photodiode detectors

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Science China(Technological Sciences) 2021年第1期64卷 59-64页

作者： LIU Zeng ZHI YuSong ZHANG ShaoHui LI Shan YAN ZuYong GAO Ang ZHANG ShiYu GUO DaoYou WANG Jun WU ZhenPing LI PeiGang TANG WeiHua Laboratory of Information Functional Materials and Devices School of ScienceBeijing University of Posts and TelecommunicationsBeijing 100876China Division of Interdisciplinary and Comprehensive Research&platform for characterization and test Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China Center for Optoelectronics Materials and Devices&Key Laboratory of Optical Field Manipulation of Zhejiang Province Department of PhysicsZhejiang Sci-Tech UniversityHangzhou 310018China China Telecom Huzhou Branch Huzhou 313000China

The low dark current, high responsivity and high specific detectivity could be preferably achieved in detectors based on junctions, owing to the efficient constraint of carriers. Compared with the other junctions, planar Schottky junctions have simple structures and technological demands and are easy integrated. Herein, in this work, we prepared the β-Ga_(2)O_(3) thin film by metalorganic chemical vapor deposition method to construct planar Ti/β-Ga2O3/Ni Schottky photodiode detectors with different onstate resistances. Fortunately, all the devices exhibit state-of-the-art performances, such as responsivity of 175–1372 A W^(-1),specific detectivity of 10^(14) Jones and external quantum efficiency of 85700%–671500%. In addition, the dependences of device performances on the on-state resistances indicate that the higher dark currents, photocurrents and photoresponsivities may well be obtained when on-state resistance is smaller, due to the less external power is used to overcome the impendence and condensance at the Ti/β-Ga_(2)O_(3) and Ni/β-Ga_(2)O_(3) interfaces, but contributing to higher electric current flow both in the dark and under illuminations.

关键词： β-Ga2O3 Schotttky photodiode solar-blind device scale on-state resistance

Catalytic Oxidative Properties and characterization of CuO/CeO_2 Catalysts

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Journal of Rare Earths 2003年第1期21卷 55-59页

作者：蒋晓原周仁贤袁骏吕光烈郑小明 Institute of Catalysis State Key Laboratory of Silicon M aterial Science Analysis and test Center Zhejiang University

The oxidative properties and characterization of CuO, CeO 2 and CuO/CeO 2 cata lysts were examined by means of a CO micro-reactor GC system, TPR, XPS and X-r ay diffraction Rietveld methods. The results show that either CuO or CeO 2 ac tivity is quite low for CO oxidation. However, when CuO and CeO 2 are mixed, the oxidative activity of the catalyst increases significantly, probably owing to the valency status of copper species (Cu 2+ and Cu+) on the CeO 2 surfa ce, the dispersion and reducibility. XPS surface analysis shows that CuO loading is very important in forming of either Cu 2+ or Cu+. Rietveld analysis s hows that some CuO, which has smaller ion radius than Ce 4+, enters the Ce O 2 lattice after CuO and CeO 2 are mixed. When the CuO loading reaches 5.0%, the size of CuO crystals is a minimum (6.1 nm) and the micro-strain value i s a maximum (2.86×10 -3), resulting in high surface energy and the best ac tivity for CO oxidation.

关键词： physical chemistry CuO/CeO 2 catalysts CO micro-reactor GC system rare earths

Production and Mechanical Behaviour of Biomedical CoCrMo Alloy

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Chinese Physics Letters 2011年第12期28卷 215-218页

作者： O.Sahin A.Rıza Tuncdemir H.Ali Cetinkara H.Salih Guder E.Sahin Department of Physics Art and Science FacultyMicro/Nanomechanic Characterization LaboratoryMustafa Kemal UniversityHatayTurkey Department of Prosthetic Dentistry Dentistry FacultyMustafa Kemal UniversityHatayTurkey

Cobalt-based alloy(Co-30Cr-5.5Mo)is produced by the investment casting *** alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength,good corrosion resistance and excellent biocompatibility ***,XRD and microhardness tests are used to examine the mechanical properties of the *** examined material exhibits the behaviour of indentation size effect(ISE).Our results reveal that Vickers and Knoop microhardness are dependent on indentation test *** traditional Meyer's law,the proportional specimen resistance(PSR)model and the Hays-Kendall model(HK)are used to analyze the load dependence of the *** a result,the Hays-Kendall model is found to be the most effective to determine the load-independent hardness HLI of CoCrMo alloy.

关键词： alloy resistance process