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研究了垂直梯度凝固法(VGF法)生长的掺Si低阻GaAs单晶材料的晶格缺陷和性质,并将VGF法和LEC法生长的非掺半绝缘GaAs单晶进行了比较. 利用A-B腐蚀显微方法比较了两种材料中的微沉积缺陷,对其形成原因进行了分析. 利用荧光光谱研究了掺Si-GaAs单晶中Si原子和B原子的占位情况和复合体缺陷. Hall测量结果表明,掺Si低阻VGF-GaAs单晶中存在很强的Si自补偿效应,造成掺杂效率降低. VGF-GaAs单晶生长过程中高的Si掺杂浓度造成晶体中产生大量杂质沉积,而杂质B的存在加重了这种现象. 对降低缺陷密度,提高掺杂效率的途径进行了分析. 相似文献
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Recent research activities on the formation of micro-defects and porosity in organic coatings were reviewed. The mechanisms of aggressive ionic conduction through organic coatings were analyzed. The micro-mechanisms for the failure behavior of coatings under corrosive environments were discussed in detail. These mechanisms included blistering (i. e. osmotic blistering, anodic blistering and cathodic blistering) in the coating, wet-adhesion loss at the substrate/coating interface, cathodic delamination of coating from the substrate. Based on these researches, it was found that the failure behavior of organic coatings is closely related to the micro-defects in coatings, regardless of the failure mode. Additionally, the general failure mode of a coating system was proposed to interpret the failure behavior of organic in corrosion environments. The topics discussed can provide some insights into the development of a methodology for designing fail-safe coating systems. 相似文献
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垂直Bridgman法生长Cr^3^+:LiCaAlF6的研究 总被引:1,自引:1,他引:1
用垂直Bridgman法从化学计量比组份的熔体中长出Cr^3^+:LiCaAlF6单晶。采用封闭式坩埚和液封技术有效地抑制了熔体的挥发和环境中微量氧的污染。生长参数为:生长速度0.7mm/h,生长温度870℃,气氛Ar。同时借助于光学湿微镜,扫描电镜,X射线能谱及波谱对晶体中的显微缺陷进行了观察和分析。对Cr^3^+:LiCaAlF6晶体的吸收光谱和发射光谱进行了测试。此外,通过红外吸收光谱发... 相似文献
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石墨电极在SEM下的特征 总被引:3,自引:0,他引:3
利用SEM(扫描电子显微镜)对石墨电极的显微结构及断口形貌进行了观察分析,探讨了石墨电极的微观结构与其性能的关系,以及微缺陷及其与断裂特性的关系,提出了生产过程中控制和减少微缺陷、提高产品质量的建议措施。 相似文献