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In this paper, the principle of discharge-based pulsed I–V technique is introduced. By using it, the energy and spatial distributions of electron traps within the 4-nm HfO_2 layer have been extracted. Two peaks are observed, which are located at ?E ~-1.0 eV and-1.43 eV, respectively. It is found that the former one is close to the SiO_2/HfO_2 interface and the latter one is close to the gate electrode. It is also observed that the maximum discharge time has little effect on the energy distribution. Finally, the impact of electrical stress on the HfO_2 layer is also studied. During stress, no new electron traps and interface states are generated. Meanwhile, the electrical stress also has no impact on the energy and spatial distribution of as-grown traps. The results provide valuable information for theoretical modeling establishment, material assessment,and reliability improvement for advanced semiconductor devices. 相似文献
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“中药槐花米中芦丁的提取”是基础有机化学实验中经典的植物提取黄酮药物的实验。分析一系列植物提取的黄酮药物分子结构,可看出它们均由2-苯基色原酮(又称黄酮)分子衍生而来。实验中,发现黄酮药物的提取率偏低,不能满足目前人们对黄酮药物的需求,因此尝试用具有高效性的化学方法合成黄酮,并进一步合成其相应的衍生物。本实验分两步合成黄酮,首先利用羟醛缩合合成2’-羟基查尔酮,然后碘催化分子内的环合得到黄酮,实验时长约为6 h,既可作为教学实验,也可作为课后的探索开放性实验。本改进实验具有安全、易操作、重复性好,特别是相对于植物提取具有产率高的优点。此外,通过本次实验的改进,引导学生采用与本实验类似的方法,设计并合成了黄酮的衍生物——乙氧黄酮(治心绞痛药物立可定中的主要活性成分)。本实验丰富了有机化学实验的教学内容,提高了分析和解决问题的能力,潜移默化地培养了学生的科学探索精神。 相似文献
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