Effect of oxygen vacancies and strain on the phonon spectrum of HfO2 thin films
Effect of oxygen vacancies and strain on the phonon spectrum of HfO2 thin films
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DOI：
10.1063/1.4984833
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发表时间：
2017-06-14
影响因子：
3.2
通讯作者：
Demkov, Alexander A.
中科院分区：
文献类型：
--
作者：
Gao, Lingyuan;Yalon, Eilam;Demkov, Alexander A.
使用第一性原理计算从理论上研究了应变和缺氧对单斜晶 HfO2 拉曼光谱的影响。研究发现，施加到 a 轴和 c 轴的 1% 面内压缩应变会使声子频率蓝移，而 1% 拉伸应变则产生相反的效果。比较了模拟结果，发现50 nm HfO2薄膜拉曼频率大于110 cm(-1)的实验结果吻合较好。发现在 110 cm(-1) 以下测量并先前分配给 HfO2 的几种拉曼模式是空气环境中存在的气体（氮气和氧气）的旋转模式。然而，通过计算确定了由三重配位氧（O-3）空位引入的局域振动模式在96.4cm(-1)处。这些结果对于更深入地了解 HfO2 的振动模式非常重要，HfO2 在晶体管中具有技术应用，特别是在依赖于缺氧 HfOx 运行的电阻式随机存取存储器中。由 AIP 出版社出版。
The effect of strain and oxygen deficiency on the Raman spectrum of monoclinic HfO2 is investigated theoretically using first-principles calculations. 1% in-plane compressive strain applied to a and c axes is found to blue shift the phonon frequencies, while 1% tensile strain does the opposite. The simulations are compared, and good agreement is found with the experimental results of Raman frequencies greater than 110 cm(-1) for 50 nm HfO2 thin films. Several Raman modes measured below 110 cm(-1) and previously assigned to HfO2 are found to be rotational modes of gases present in air ambient (nitrogen and oxygen). However, localized vibrational modes introduced by threefold-coordinated oxygen (O-3) vacancies are identified at 96.4cm(-1) computationally. These results are important for a deeper understanding of vibrational modes in HfO2, which has technological applications in transistors and particularly in resistive random-access memory whose operation relies on oxygen-deficient HfOx. Published by AIP Publishing.