Thickness dependent wetting properties and surface free energy of HfO2 thin films
Thickness dependent wetting properties and surface free energy of HfO2 thin films
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DOI：
10.1063/1.4953262
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发表时间：
2016-06
影响因子：
4
通讯作者：
S. Zenkin;A. Belosludtsev;Š. Kos;R. Čerstvý;S. Haviar;M. Netrvalová
中科院分区：
文献类型：
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作者：
S. Zenkin;A. Belosludtsev;Š. Kos;R. Čerstvý;S. Haviar;M. Netrvalová
我们发现，HfO2薄膜的本征疏水性可以很容易地通过改变薄膜厚度来调节。我们采用反应高功率脉冲磁控溅射的方法制备了表面光滑、厚度可控的高质量HfO2薄膜。结果表明，由于表面自由能中的静电Lifshitz-van der Waals分量占主导地位，在50-250 nm范围内，润湿性能与薄膜厚度有很强的相关性。结果表明，50 nm水滴的接触角为≈120°，2300 nm水滴的接触角为≈100°。同时，表面自由能从厚度为50 nm的≈25mJ/m2增加到厚度为2300 nm的≈33mJ/m2。我们对观察到的润湿性质与厚度的关系提出了两种解释：非主导织构的影响和/或粒子表面能的非单调尺寸关系。
We show here that intrinsic hydrophobicity of HfO2 thin films can be easily tuned by the variation of film thickness. We used the reactive high-power impulse magnetron sputtering for preparation of high-quality HfO2 films with smooth topography and well-controlled thickness. Results show a strong dependence of wetting properties on the thickness of the film in the range of 50–250 nm due to the dominance of the electrostatic Lifshitz-van der Waals component of the surface free energy. We have found the water droplet contact angle ranging from ≈120° for the thickness of 50 nm to ≈100° for the thickness of 2300 nm. At the same time the surface free energy grows from ≈25 mJ/m2 for the thickness of 50 nm to ≈33 mJ/m2 for the thickness of 2300 nm. We propose two explanations for the observed thickness dependence of the wetting properties: influence of the non-dominant texture and/or non-monotonic size dependence of the particle surface energy.