Direct and defect-assisted electron tunneling through ultrathin SiO 2 layers from first principles
Direct and defect-assisted electron tunneling through ultrathin SiO 2 layers from first principles
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DOI：
10.1103/physrevb.77.195321
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发表时间：
2008-05
影响因子：
3.7
通讯作者：
Joongoo Kang;Yong‐Hoon Kim;J. Bang;K. Chang
中科院分区：
文献类型：
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作者：
Joongoo Kang;Yong‐Hoon Kim;J. Bang;K. Chang
利用第一性原理矩阵绿色函数方法研究了金属氧化物半导体器件中超薄层的相干电荷隧穿。隧穿行为进行了分析，在原子的图片的基础上，在氧化物区域中的Si诱导的间隙状态的重叠。我们发现，虽然界面粗糙度缺陷，如亚氧化物键和突出的O原子只有微弱的影响隧穿电流，整个氧化层的硅硅键组成的氧空位网络急剧增加的栅极漏电流由于缺陷辅助隧穿。我们表明，这种渗流路径的形成是积极有利的非平衡状态下，甚至氧双空位是足以导致介电击穿的氧化物层。
We perform first-principles matrix Green’s function calculations to study the coherent charge tunneling through ultrathinlayers in metal-oxide-semiconductor devices. The tunneling behavior is analyzed within the atomistic picture based on the overlap of Si-induced gap states in the oxide region. We find that, while interface roughness defects such as suboxide bonds and protruded O atoms only weakly affect the tunneling current, a network of oxygen vacancies composed of Si-Si bonds across the oxide layer drastically increases the gate leakage current due to the defect-assisted tunneling. We show that the formation of such percolation paths is energetically favorable in the nonequilibrium situation, and even the oxygen divacancy is enough to result in the dielectric breakdown for ultrathin oxide layers.