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Hydrochloric Acid-Promoted Synthesis of cBN via Hydrothermal Route

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Journal of Materials Science & Technology 2007年第6期23卷 768-770页

作者： Haihui jiang Kai LI Ligang GAI Qilong WANG Deliang CUI minhua jiang State Key Lab of Crystal Materials Shandong University Jinan 250100 China School of Chemistry and Chemical Engineering Shandong University Jinan 250100 China School of Chemical Engineering Shandong Institute of Light Industry Jinan 250353 China

Single phase crystalline cubic boron nitride （cBN） with high yield was prepared by hydrothermal route at low temperature, using hydrochloric acid （HCI） as the promoter. The promotion effect of HCI on the synthesis... 详细信息

关键词： Hydrochloric acid-promoted Cubic boron nitride Hydrothermal route

Synthesis of High Purity SiC Powder for High-resistivity SiC Single Crystals Growth

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Journal of Materials Science & Technology 2007年第1期23卷 118-122页

作者： Li WANG Xiaobu HU Xiangang XU Shouzheng jiang Lina NING minhua jiang State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

High purity silicon carbide （SIC） powder was synthesized in-situ by chemical reaction between silicon and carbon powder. In order to ensure that the impurity concentration of the resulting SiC powder is suitable for high-resistivity SiC single crystal growth, the preparation technology of SiC powder is different from that of SiC ceramic. The influence of the shape and size of carbon particles on the morphology and phase composition of the obtained SiC powder were discussed. The phase composition and morphology of the products were investigated by X-ray diffraction, Raman microspectroscopy and scanning electron microscopy. The results show that the composition of resulting SiC by in-situ synthesis from Si/C mixture strongly depends on the nature of the carbon source, which corresponds to the particle size and shape, as well as the preparation temperature. In the experimental conditions, flake graphite is more suitable for the synthesis of SiC powder than activated carbon because of its relatively smaller particle size and flake shape, which make the conversion more complete. The major phase composition of the full conversion products is β-SiC, with traces of α-SiC. Glow discharge mass spectroscopy measurements indicated that SiC powder synthesized with this chemical reaction method can meet the purity demand for the growth of high-resistivity SiC single crystals.

关键词： Activated carbon Flaky graphite Particle size SiC powder High purity

Investigation of the 6H-SiC (0001) surface by AFM

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Journal of University of Science and Technology Beijing 2008年第5期15卷 654-658页

作者： Shouzhen jiang Guangwei Yu Yingmin Wang Xiaobo Hu Xiangang Xu minhua jiang State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China College of Physics and Electronics Shandong Normal University Jinan 250014 China

Micropipe and step structures on 6H-SiC （0001） surface were investigated by an atomic force microscopy （AFM）. On the facet,all micropipes examined are the origins of spiral steps,indicating that dislocations intersect the surface at these points. Micropipes are empty-core super-dislocations as originally described by Frank. The micropipe radius increases with the square of the dislocation Burgers vector. From the center to the periphery,step structures change with different surface inclinations. Regular step is observed within the central faceted area. Step bunching and atomically rough surfaces are observed within the peripheral convex area. If the inclination with respect to the （0001） plane is large enough,step bunching of 15R-SiC can be observed.

关键词： atomic force microscopy micropipes step bunching polytypes

A NEW NONLINEAR OPTICAL MATERIAL-ORGANOMETALLIC COMPLEX TRIALLYLTHIOUREA MERCURY CHLORIDE

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Chinese Physics Letters 1990年第7期7卷 334-336页

作者： YUAN Duorong ZHANG Nan TAO Xutang XU Dong jiang minhua Institute of Crystal Materials Shandong UniversityJinan 250100

Tri-allylthiourea mercury chloride(ATMC),an organometallic complex,is a new nonlinear optical material with high second harmonic generation(SHG)*** SHG effect of ATMC is three times as large as that of urea *** single crystal of 15×15×10mm^(3) has been *** studies of crystal growth,structure,and general properties have been carried *** results show that organometallic complexes are promising nonlinear optical materials for wide applications.

关键词： effect crystal nonlinear

Fine Machining of Large-Diameter 6H-SiC Wafers

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Journal of Materials Science & Technology 2006年第5期22卷 681-684页

作者： Xiufang CHEN Juan LI Deying MA Xiaobo HU Xiangang XU minhua jiang State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

Three main machining processes of large-diameter 6H-SiC wafers were introduced in this paper. These processes include cutting, lapping and polishing. Lapping causes great residual stresses and deep damage layer which can be reduced gradually with subsequent polishing processes. Surfaces prepared by mechanical polishing （MP） appeared a large number of scratches with depth of 5-8 nm. These scratches can be effectively removed by chemo-mechanical polishing （CMP）. After CMP. extremely smooth and low damage layer surface with roughness Ra=0.3 nm was obtained. Atomic force microscopy （AFM） and optical microscopy were used to observe the surface morphology of samples and a high resolution X-ray diffractometer （HRXRD） was used for the crystal lattice perfection of the subsurface region. Changes of surface residual stresses during machining processes were investigated by HRXRD.

关键词： 6H-SiC Chemo-mechanical polishing (CMP) Roughness

2H-SiC Dendritic Nanocrystals In Situ Formation from Amorphous Silicon Carbide under Electron Beam Irradiation

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Journal of Rare Earths 2006年第Z1期24卷 54-55页

作者： Li Xianxiang Hu Xiaobo jiang Shouzheng Dong Jie Xu Xiangang jiang minhua State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

Under electron beam irradiation,the in-situ formation of 2H-SiC dentritic nanocrystals from amorphous silicon carbide at room temperature was *** homogenous transition mainly occurs at the thin edge and on the surface of specimen where the energy obtained from electron beam irradiation is high enough to cause the amorphous crystallizing into 2H-SiC.

关键词： electron beam irradiation 2H-SiC dendritic nanocrystal amorphous silicon carbide

Formation of the Bicrystal Structure of KTiOPO_(4) Crystals

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Chinese Physics Letters 1994年第7期11卷 431-434页

作者： SHI Luping WANG Jiyang LIU Yaogang SHAO Zongshu jiang minhua LIU Xiangyang Institute of Crystal Materials Shandong UniversityJi’nan 250100 Institute of Research on the Structure of Material Academia SinicaFuzhou 350002

In this paper,by comparing the three possible combinations of the basic structure unit TiO_(6) octahedra,a simple model is proposed to explain the cause of the formation of the bicrystal structure in KTiOPO_(4)(KTP)*** theoretical morphology of KTP crystal is studied and the rate of the appearance possibilities of different faces are *** relationships between bicrystal structure and crystal properties are discussed.

关键词： KTiOPO4 crystal crystals

Thermal Oxidation of Silicon Carbide Substrates

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Journal of Materials Science & Technology 2009年第1期25卷 115-118页

作者： Xiufang Chen Liana Ning Yingmin Wang Juan Li Xiangang Xu Xiaobo Hu minhua jiang State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Thermal oxidation was used to remove the subsurface damage of silicon carbide （SIC） surfaces. The anisotropy of oxidation and the composition of oxide layers on Si and C faces were analyzed. Regular pits were observed on the surface after the removal of the oxide layers, which were detrimental to the growth of high quality epitaxial layers. The thickness and composition of the oxide layers were characterized by Rutherford backscattering spectrometry （RBS） and X-ray photoelectron spectroscopy （XPS）, respectively. Epitaxial growth was performed in a metal organic chemical vapor deposition （MOCVD） system. The substrate surface morphology after removing the oxide layer and gallium nitride （GaN） epilayer surface were observed by atomic force microscopy （AFM）. The results showed that the GaN epilayer grown on the oxidized substrates was superior to that on the unoxidized substrates.

关键词： SiC Thermal oxidation GaN epitaxy

Surface Polishing of 6H-SiC Substrates

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Journal of Materials Science & Technology 2007年第3期23卷 430-432页

作者： Xiufang CHEN Xiangang XU Juan LI Shouzhen jiang Lina NING Yingmin WANG Deying MA Xiaobo HU minhua jiang State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

The surface polishing for silicon carbide （SIC） substrates was investigated and results were presented for mechanical polishing （MP） and chemo-mechanical polishing （CMP）. High quality surfaces were obtained after CMP with colloidal silica. The removal mechanism of scratches in MP and detailed physical and chemical process during CMP were analyzed. The effects of MP and CMP on the surface roughness were assessed by optical microscopy （OM）, atomic force microscopy （AFM） and step profilometry. KOH etching and high resolution X-ray diffractometry （H RXRD） were applied to evaluate the subsurface damage of 6H-SiC substrates.

关键词： SiC Chemo-mechanical polishing (CMP) Roughness Subsurface damage