Growth Window of Ferroelectric Epitaxial Hf0.5Zr0.5O2 Thin Films
Growth Window of Ferroelectric Epitaxial Hf0.5Zr0.5O2 Thin Films
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DOI：
10.1021/acsaelm.8b00065
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发表时间：
2019-02-01
影响因子：
4.7
通讯作者：
Sanchez, Florencio
中科院分区：
文献类型：
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作者：
Lyu, Jike;Fina, Ignasi;Sanchez, Florencio
氧化铪的亚稳态斜方晶相通常在多晶薄膜中获得，而在外延薄膜中，对其形成的研究要少得多。我们通过脉冲激光沉积生长了 Hf0.5Zr0.5O2 薄膜，并绘制了铁电相外延稳定的生长窗口（沉积期间的温度和氧压以及薄膜厚度）。残余铁电极化程度高达 24 μ 4C/cm(2)，取决于斜方相的数量和晶面间距，并且对于固定的膜厚度而言，其随着温度和压力的增加而增加。漏电流随着厚度或温度的增加或氧气压力的降低而降低。矫顽电场 (E-C) 取决于厚度 (t)，根据 E-C - t(-2/3) 比例，这是首次在铁电二氧化铪中观察到，并且比例延伸到厚度低至 5 nm 左右。定制高质量外延铁电 Hf0.5Zr0.5O2 薄膜功能特性的能力已得到证实，这为了解其铁电特性和原型器件铺平了道路。
The metastable orthorhombic phase of hafnia is generally obtained in polycrystalline films, whereas in epitaxial films, its formation has been much less investigated. We have grown Hf0.5Zr0.5O2 films by pulsed laser deposition, and the growth window (temperature and oxygen pressure during deposition and film thickness) for epitaxial stabilization of the ferroelectric phase is mapped. The remnant ferroelectric polarization, up to similar to 24 mu 4C/cm(2), depends on the amount of orthorhombic phase and interplanar spacing and increases with temperature and pressure for a fixed film thickness. The leakage current decreases with an increase in thickness or temperature, or when decreasing oxygen pressure. The coercive electric field (E-C) depends on thickness (t) according to the E-C - t(-2/3) scaling, which is observed for the first time in ferroelectric hafnia, and the scaling extends to thicknesses down to around 5 nm. The proven ability to tailor the functional properties of high-quality epitaxial ferroelectric Hf0.5Zr0.5O2 films paves the way toward understanding their ferroelectric properties and prototyping devices.