Effect of the film thickness on the crystal structure and ferroelectric properties of (Hf0.5Zr0.5)O2 thin films deposited on various substrates
Effect of the film thickness on the crystal structure and ferroelectric properties of (Hf0.5Zr0.5)O2 thin films deposited on various substrates
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DOI：
10.1016/j.mssp.2016.12.008
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发表时间：
2017-11-01
影响因子：
4.1
通讯作者：
Funakubo, Hiroshi
中科院分区：
文献类型：
--
作者：
Shiraishi, Takahisa;Katayama, Kiliha;Funakubo, Hiroshi
研究了薄膜厚度对（Hf_（0.5）Zr_（0.5））O_2薄膜晶体结构和铁电性能的影响。薄膜沉积在（111）Pt涂层的SiO2，Si和CaF 2衬底上，热膨胀系数分别为0.47，4.5和22 × 10（-6）/℃。从X射线衍射测量，它被发现，（Hf0.5Zr0.5）O-2薄膜沉积在SiO2和CaF 2基板上经历了面内拉伸和压缩应变，分别与沉积在Si基板上的薄膜。对于沉积在所有三个衬底上的膜，单斜相的体积分数随着膜厚度的增加而增加，其中SiO2衬底在所有测试的膜厚度下具有最低的单斜相体积分数。的薄膜，这是铁电相的形成的一个重要因素的晶粒尺寸，保持几乎恒定在约10纳米的直径，无论膜厚度和类型的基板使用。在SiO2和Si衬底上沉积的17 nm厚的薄膜观察到了铁电性，在SiO2衬底上沉积的薄膜获得了9.3 μ C/cm（2）的最大反射极化（P-r）值。与此相反，铁电性与P-r=4.4 μ C/cm（2）的情况下，只有在55 nm厚的膜的SiO2衬底上的膜观察。这些结果表明，在面内拉伸应变下的薄膜在17 nm厚的薄膜中具有较大的铁电性，并且具有高达55 nm厚的薄膜的铁电性。
In this work, the effect of the film thickness on the crystal structure and ferroelectric properties of (Hf0.5Zr0.5)O-2 thin films was investigated. The thin films were deposited on (111) Pt-coated SiO2, Si, and CaF2 substrates with thermal expansion coefficients of 0.47, 4.5, and 22 x 10(-6)/degrees C, respectively. From the X-ray diffraction measurements, it was found that the (Hf0.5Zr0.5)O-2 thin films deposited on the SiO2 and CaF2 substrates experienced in-plane tensile and compressive strains, respectively, in comparison with the films deposited on the Si substrates. For films deposited on all three substrates, the volume fraction of the monoclinic phase increased with increasing film thickness, with the SiO2 substrate having the lowest monoclinic phase volume fraction at all film thicknesses tested. The grain size of the films, which is an important factor for the formation of the ferroelectric phase, remained almost constant at about 10 nm in diameter regardless of the film thickness and type of substrate utilized. Ferroelectricity was observed for the 17 nm-thick films deposited on SiO2 and Si substrates, and the maximum remanent polarization (P-r) value of 9.3 mu C/cm(2) was obtained for films deposited on the SiO2 substrate. In contrast, ferroelectricity with P-r=4.4 mu C/cm(2) was observed only for film on SiO2 substrate in case of 55 nm-thick films. These results suggest that the films under in-plane tensile strain results in the larger ferroelectricity for 17 nm-thick films and have a ferroelectricity up to 55 nm-thick films.