Inhomogeneities in Ni∕4H-SiC Schottky barriers: Localized Fermi-level pinning by defect states
Inhomogeneities in Ni∕4H-SiC Schottky barriers: Localized Fermi-level pinning by defect states
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DOI：
10.1063/1.2745436
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发表时间：
2007-06
影响因子：
3.2
通讯作者：
D. Ewing;L. Porter;Q. Wahab;Xianyun Ma;T. S. Sudharshan;S. Tumakha;M. Gao;L. Brillson
中科院分区：
文献类型：
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作者：
D. Ewing;L. Porter;Q. Wahab;Xianyun Ma;T. S. Sudharshan;S. Tumakha;M. Gao;L. Brillson
我们使用电流-电压 (I-V) 测量、电子束感应电流 (EBIC)、偏振光显微镜、X 射线形貌和深度分辨阴极发光光谱研究了 n 型 4H-SiC 外延层上的 Ni、Pt 或 Ti 肖特基二极管阵列。很大一部分二极管（~7%–30%，取决于外延生长方法和二极管尺寸）表现出“非理想”或不均匀的势垒高度特性。我们使用基于两个并联二极管的热电子发射模型来确定各个非理想二极管内高势垒和低势垒区域的势垒高度和理想因子。高势垒势垒高度随着金属功函数的增加而增加，而低势垒势垒高度则保持恒定在~0.60、0.85 和 1.05eV。使用各种光谱和成像技术研究了这些非理想性的来源，以确定缺陷的性质和能量水平。 EBIC 表明所有非均质二极管中均出现缺陷簇。阴极...
We investigated arrays of Ni, Pt, or Ti Schottky diodes on n-type 4H-SiC epitaxial layers using current-voltage (I-V) measurements, electron beam induced current (EBIC), polarized light microscopy, x-ray topography, and depth-resolved cathodoluminescence spectroscopy. A significant percentage of diodes (∼7%–30% depending on epitaxial growth method and diode size) displayed “nonideal” or inhomogeneous barrier height characteristics. We used a thermionic emission model based on two parallel diodes to determine the barrier heights and ideality factors of high- and low-barrier regions within individual nonideal diodes. Whereas high-barrier barrier heights increased with metal work function, low-barrier barrier heights remained constant at ∼0.60, 0.85, and 1.05eV. The sources of these nonidealities were investigated with a variety of spectroscopic and imaging techniques to determine the nature and energy levels of the defects. EBIC indicated that clusters of defects occurred in all inhomogeneous diodes. Cathod...