講演情報
[18p-B3-8]Electro-optic properties of Hf0.5Zr0.5O2 thin films on (La, Sr)MnO3/SrTiO3(100)
〇(D)Afeefa Dastgir1, Yuan Xueyou1, Yufan Shen2, Daisuke Kan2, Yuichi Shimakawa2, Tomoaki Yamada1,3 (1.Nagoya Univ., 2.Kyoto Univ., 3.Tokyo Tech, MDX)
キーワード：
Ferroelectric、Thin film
Ferroelectricity in HfO2-based thin films is attractive for applications in ferroelectric random access memory and ferroelectric tunnelling junctions. We recently found that the Y-doped HfO2 thin films exhibit the linear electro-optic (EO) property. Although the observed EO coefficient was below 1 pm/V, which is one or two order magnitudes smaller than that of conventional ferroelectric EO materials, it is interesting for the Si-integrated photonics as HfO2 is highly compatible with CMOS process. Therefore, the enhancement of EO coefficient in HfO2-based thin films can be expected. In this study, we investigated the thickness-dependence of EO property in Hf0.5Zr0.5O2 (HZO) thin films, revealing an enhanced EO response in 10 nm-thick films compared to thicker films. HZO films were deposited on (La, Sr)MnO3/SrTiO3(100) using pulsed laser deposition, with the thickness in the range of 3 to 30 nm.There is A partial phase transition from ferroelectric orthorhombic to paraelectric monoclinic with increasing film thickness from 10 nm to 30 nm, meaning that both orthorhombic and monoclinic phases coexist in the 30 nm-thick film. The EO response of those films was characterized using in-house modulation ellipsometry. It was found that both 10 nm and 30 nm films exhibited evident linear EO response, and the EO coefficient for the 10 nm-thick film was 1.0 pm/V, which was larger than that for the 30 nm-thick film (0.8 pm/V). This implies that the larger volume fraction of ferroelectric orthorhombic phase in thinner films contributed to the larger EO response.
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