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Bulk single crystal growth of SiGe by PMCZ method

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Rare Metals 2003年第3期22卷 197-201页

作者： ZHANG Weilian, NIU Xinhuan, CHEN Hongjian, ZHANG Jianxin, SUN Junsheng, and ZHANG Enhuaisemiconductor material institute, Hebei University of Technology, Tian jin 300130, China semiconductor material institute Hebei University of Technology 天津 300130

A new type of magnetic device was used to replace the conventionalelectro-magnetic field for CZSi (doped with Ge) growth. The device was composed of three permanentmagnetic rings and called PMCZ device. The lines of magnetic force are horizontally distributed atradial 360℃. Using the ring permanent magnetic field, thermal convection in melt and centrifugalpumping flows due to crystal rotation could be strongly suppressed so that the fluctuations oftemperature and micro-growth rate at solid/liquid interface could be restrained effectively. In thePMCZ condition, the growing environment of SiGe bulk single crystal was similar to the crystalgrowth in space under the condition of micro-gravity. The motion of impurities (Ge, oxygen, etc.)had been controlled by diffusion near the solid/liquid interface. Oxygen concentration became lowerand the distribution of composition became more homogeneous along longitudinal direction and acrossa radial section in the grown SiGe crystal. The mechanism of PMCZ superior to MCZ was alsodiscussed.

关键词： SiGe single crystal composition homogeneous PMCZ thermal convection crystal growth

Determination of the transport properties in 4H-SiC wafers by Raman scattering measurement

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Chinese Physics B 2011年第3期20卷 185-190页

作者：孙国胜刘兴昉吴海雷闫果果董林郑柳赵万顺王雷曾一平李锡光王占国 Key Laboratory of semiconductor material Sciences Institute of Semiconductors Chinese Academy of Sciences material Science Center Institute of SemiconductorsChinese Academy of Sciences Dongguan Tianyu semiconductor Inc.

The free carrier density and mobility in n-type 4H-SiC substrates and epilayers were determined by accurately analysing the frequency shift and the full-shape of the longitudinal optic phono-plasmon coupled （LOPC） modes, and compared with those determined by Hall-effect measurement and that provided by the vendors. The transport properties of thick and thin 4H-SiC epilayers grown in both vertical and horizontal reactors were also studied. The free carrier density ranges between 2× 10^18 cm^-3 and 8× 10^18 cm^-3with a carrier mobility of 30-55 cm2/（V.s） for ntype 4H-SiC substrates and 1× 10^16 -3× 10^16 cm^-3 with mobility of 290-490 cm2/（V.s） for both thick and thin 4H-SiC epilayers grown in a horizontal reactor, while thick 4H-SiC epilayers grown in vertical reactor have a slightly higher carrier concentration of around 8.1×10^16 cm^-3 with mobility of 380 cm2/（V.s）. It was shown that Raman spectroscopy is a potential technique for determining the transport properties of 4H-SiC wafers with the advantage of being able to probe very small volumes and also being non-destructive. This is especially useful for future mass production of 4H-SiC epi-wafers.

关键词： 4H-SiC Raman scattering LOPC modes transport properties

Thermoelectric Properties of Czochralski GeSi Crystal

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Chinese Journal of Structural Chemistry 2007年第10期26卷 1247-1251页

作者：索开南张维连林健赵嘉鹏周子鹏 semiconductor material institute Hebei University of Technology The 46th Research institute CETC

In order to discuss the application possibility of SiGe crystal in thermoelectric materials, we investigated the thermoelectric properties of several silicon-germanium alloys with different content, orientation and electric conductive type. As discussed in the experiment result, the absolute value of Seebeck coefficient fluctuates from 300 to 600 μV/K in the whole temperature range. In the present paper, the relationship of Seebeck coefficient against content, orientation and electric conductive type is summarized in detail. The Seebeck coefficient of the sample with 〈111〉 orientation is smaller than that in 〈100〉 at the same temperature. Absolute value of P-type is larger than that of N-type except pure Ge. But as the temperature increases, the absolute value of pure Ge decreases many times as quickly as that of other specimens. In addition, the specimens of bulk GeSi alloy crystals for experiment were grown by the Czoehralski method through varying the pulling rate during the growing process.

关键词： SiGe alloy single crystal thermoelectric properties Seebeck coefficient

Raman Scattering Detection of Stacking Faults in Free-Standing Cubic-SiC Epilayer

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Chinese Physics Letters 2006年第10期23卷 2834-2837页

作者：刘兴昉孙国胜李晋闽赵永梅李家业王雷赵万顺曾一平 Novel semiconductor material Laboratory Institute of Semiconductors Chinese Academy of Sciences Beijing 100083

We report on stacking fault （SF） detection in free-standing cubic-SiC epilayer by the Raman measurements. The epilayer with enhanced SFs is heteroepitaxially grown by low pressure chemical vapour deposition on a Si（100） substrate and is released in KOH solution by micromechanical manufacture, on which the Raman measurements are performed in a back scattering geometry. The TO line of the Raman spectra is considerably broadened and distorted. We discuss the influence of SFs on the intensity profiles of TO mode by comparing our experimental data with the simulated results based on the Raman bond polarizability （BP） model in the framework of linearchain concept. Cood agreement with respect to the linewidth and disorder-induced peak shift is found by assuming the mean distance of the SFs to be 11 A in the BP model.

关键词： SPECTROSCOPY GROWTH POLYTYPES SILICON

High-quality homoepitaxial layers grown on 4H-SiC at a high growth rate by vertical LPCVD

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Journal of semiconductors 2011年第4期32卷 44-47页

作者：吴海雷孙国胜杨挺闫果果王雷赵万顺刘兴昉曾一平温家良 Novel semiconductor material Laboratory Institute of SemiconductorsChinese Academy of Sciences China Electric Power Research institute

High quality,homoepitaxial layers of 4H-SiC were grown on off-oriented 4H-SiC（0001） Si planes in a vertical low-pressure hot-wall CVD system（LPCVD） by using trichlorosilane（TCS） as a silicon precursor source together with ethylene（C;H;） as a carbon precursor *** growth rate of 25-30μm/h has been achieved at lower temperatures between 1500 and 1530℃.The surface roughness and crystalline quality of 50μm thick epitaxial layers（grown for 2 h） did not deteriorate compared with the corresponding results of thinner layers（grown for 30 min）.The background doping concentration was reduced to 2.13×10;cm;.The effect of the C/Si ratio in the gas phase on growth rate and quality of the epi-layers was investigated.

关键词： 4H-SiC homoepitaxial growth vertical hot wall CVD crystal morphology

High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

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Chinese Physics B 2013年第9期22卷 568-573页

作者：郑柳张峰刘胜北董林刘兴昉樊中朝刘斌闫果果王雷赵万顺孙国胜何志杨富华 Key Laboratory of semiconductor material Sciences Institute of SemiconductorsChinese Academy of Sciences Engineering Research Center for semiconductor Integrated Technology Institute of SemiconductorsChinese Academy of Sciences

4H-SiC junction barrier Schottky （JBS） diodes with a high-temperature annealed resistive termination extension （HARTE） are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 mΩ·cm^2 with a total active area of 2.46× 10 ^-3 cm^2. Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7 V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250 ℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9× 10^-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.

关键词： 4H-SiC junction barrier Schottky (JBS) diode high-temperature annealed resistive terminationextension (HARTE)

Influences of annealing on structural and compositional properties of Al_2O_3 thin films grown on 4H–SiC by atomic layer deposition

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Chinese Physics B 2016年第12期25卷 468-473页

作者：田丽欣张峰申占伟闫果果刘兴昉赵万顺王雷孙国胜曾一平 Key Laboratory of semiconductor material Sciences Beijing Key Laboratory of Low Dimensional Semiconductor Materials and DevicesInstitute of SemiconductorsChinese Academy of Sciences

Annealing effects on structural and compositional performances of A1203 thin films on 4H-SiC substrates are studied comprehensively. The Al2O3 films are grown by atomic layer deposition through using trimethylaluminum and H2O as precursors at 300 ℃, and annealed at various temperatures in ambient N2 for 1 min. The Al2O3 film transits from amorphous phase to crystalline phase as annealing temperature increases from 750 ℃ to 768 ℃. The refractive index increases with annealing temperature rising, which indicates that densification occurs during annealing. The densification and grain formation of the film upon annealing are due to crystallization which is relative with second-nearest-neighbor coordination variation according to the x-ray photoelectron spectroscopy （XPS）. Although the binding energies of Al 2p and O ls increase together during crystallization, separations between Al 2p and O ls are identical between as-deposited and annealed sample, which suggests that the nearest-neighbour coordination is similar.

关键词： atomic layer deposition annealing transition 4H-SiC

Characterization of 4H-SiC substrates and epilayers by Fourier transform infrared reflectance spectroscopy

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Chinese Physics B 2012年第4期21卷 548-554页

作者：董林孙国胜郑柳刘兴昉张峰闫果果赵万顺王雷李锡光王占国 material Science Center Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Key Laboratory of semiconductor material Sciences Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Dongguan Tianyu semiconductor Inc. Dongguan 523000China

The infrared reflectance spectra of both 4H SiC substrates and epilayers are measured in a wave number range from 400 cm 1 to 4000 cm-1 using a Fourier-transform spectrometer. The thicknesses of the 4H-SiC epilayers and the electrical properties, including the free-carrier concentrations and the mobilities of both the 4H SiC substrates and the epilayers, are characterized through full line-shape fitting analyses. The correlations of the theoretical spectral profiles with the 4H-SiC electrical properties in the 30 cm-1-4000 cm 1 and 400 cm-1-4000 cm-1 spectral regions are established by introducing a parameter defined as error quadratic sum. It is indicated that their correlations become stronger at a higher carrier concentration and in a wider spectral region （30 cm-1-4000 cm-1）. These results suggest that the infrared reflectance technique can be used to accurately determine the thicknesses of the epilayers and the carrier concentrations, and the mobilities of both lightly and heavily doped 4H-SiC wafers.

关键词： 4H SiC infrared reflectance epilayer thickness electrical properties

High-energy-density lithium manganese iron phosphate for lithium-ion batteries: Progresses, challenges, and prospects

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Journal of Energy Chemistry 2025年第1期100卷 1-17页

作者： Bokun Zhang Xiaoyun Wang Shuai Wang Yan Li Libo Chen Handong Jiao Zhijing Yu Jiguo Tu State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Research institute for Intelligent Wearable Systems The Hong Kong Polytechnic University institute of Advanced Structure Technology Beijing Institute of Technology

The soaring demand for smart portable electronics and electric vehicles is propelling the advancements in high-energy–density lithium-ion *** manganese iron phosphate (LiMnxFe1-xPO4) has garnered significant attention as a promising positive electrode material for lithium-ion batteries due to its advantages of low cost,high safety,long cycle life,high voltage,good high-temperature performance,and high energy *** LiMnxFe1-xPO4has made significant breakthroughs in the past few decades,there are still facing great challenges in poor electronic conductivity and Li-ion diffusion,manganese dissolution affecting battery cycling performance,as well as low tap *** review systematically summarizes the reaction mechanisms,various synthesis methods,and electrochemical properties of LiMnxFe1-xPO4to analyze reaction processes accurately and guide material ***,the main challenges currently faced are concluded,and the corresponding various modification strategies are discussed to enhance the reaction kinetics and electrochemical performance of LiMnxFe1-xPO4,including multi-scale particle regulation,heteroatom doping,surface coating,as well as microscopic morphology ***,in view of the current research challenges faced by intrinsic reaction processes,kinetics,and energy storage applications,the promising research directions are *** importantly,it is expected to provide key insights into the development of high-performance and stable LiMnxFe1-xPO4materials,to achieve practical energy storage requirements.

关键词： semiconductor doping