Interface characteristics affecting electrical properties of Y-doped SiC
Interface characteristics affecting electrical properties of Y-doped SiC
复制标题
影响 Y 掺杂 SiC 电性能的界面特性
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
L. Sigl
中科院分区：
文献类型：
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作者：
F. Siegelin;H. Kleebe;L. Sigl
掺杂 3 vol% AlN、Al_2OC、Y_3Al_5O_12 的液相烧结 SiC 在烧结过程中发生微小变化时，电阻率变化超过五个数量级 (<10^2-10^7 Ω cm)。使用各种透射电子显微镜技术对材料进行了表征，例如高分辨率透射电子显微镜（HRTEM）、菲涅耳条纹成像、分析电子显微镜和电子全息术。本研究的主要目的是验证界面结构与电阻率之间是否存在相关性。抛光和等离子蚀刻表面的扫描电子显微镜（SEM）显示出与含有非晶晶界膜的 Si_3N_4 陶瓷中观察到的界面特征相似的界面特征。此类薄膜有望充当电流的绝缘屏障。然而，与 SEM 结果相反，SiC 晶界的 HRTEM 显示在所研究的任何 SiC 材料中都没有晶间膜。这些“干净的”SiC 界面的元素分析（即能量色散 X 射线和电子能量损失光谱）显示出第二相元素在晶界处的偏析。电子全息术和菲涅尔条纹技术被用来确定跨 SiC 界面的平均内部电势的变化，这可能与双肖特基势垒的空间电荷分布有关。势垒的高度与通过阻抗谱记录的电阻率相关。
Liquid-phase sintered SiC, doped with 3 vol% AlN, Al_2OC, Y_3Al_5O_12, revealed a variation in electrical resistivity of more than five orders of magnitude (<10^2-10^7 Ω cm) upon slight variations in the sintering process. The materials were characterized using various transmission electron microscopy techniques such as high-resolution transmission electron microscopy (HRTEM), Fresnel fringe imaging, analytical electron microscopy, and electron holography. The main focus of this study was to verify whether there is a correlation between interface structure and electrical resistivity. Scanning electron microscopy (SEM) of polished and plasma-etched surfaces showed interface features similar to those observed in Si_3N_4 ceramics containing amorphous grain-boundary films. Such films are expected to act as an insulating barrier for electric current. However, in contrast to the SEM results, HRTEM of SiC grain boundaries revealed no intergranular film in any of the SiC materials studied. Elemental analysis (i.e., energy dispersive x-ray and electron energy loss spectroscopy) of these “clean” SiC interfaces showed the segregation of secondary phase elements at grain boundaries. Electron holography and the Fresnel fringe technique were used to determine the change in the mean inner potential across SiC interfaces, which could be associated with the spatial charge distribution of a double Schottky barrier. The height of the potential barrier correlates with the electrical resistivity recorded via impedance spectroscopy.