Qiang Wang , Haoyan Meng , Yexuan Guo , Yankun Wang , Liyan Dai , Jinyan Zhao , Libo Zhao , Zhuangde Jiang , Jutta Schwarzkopf , Shengli Wu , Lifeng Liu , Chuanmin Wang , Zongmin Wang , Fei Chu , Yong Wang , Wei Ren , Gang Niu
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引用次数: 0
Abstract
Ferroelectric hafnium-oxide (HfO2) films have a great potential for integrated non-volatile memories, neuromorphic computation and micro-electro-mechanical systems (MEMS), thanks to its compatibility with mainstream semiconductor fabrication process. However, the high-quality ferroelectric single-crystal HfO2 films, deemed as the consequence of the non-centrosymmetric orthorhombic o (111) phase, are still challenging to be reliably prepared. It is because various phase structures like monoclinic phase, tetragonal phase or cubic phase are possible to be formed accompanying with orthorhombic o (111) phase. The crystalline phase of HfO2 is related to the doping, the lattice strain, the film thickness and the orientation of substrate, however the comprehensive understandings of different factors are still lacking. We report in this work the growth and optimization of o (1 1 1) phase Y-doped HfO2 (HYO) films deposited on La2/3Sr1/3MnO3/SrTiO3 and comprehensively clarify the influence of the substrate orientation, the film thickness, and the oxygen pressure on crystal behaviors of HYO films. By comparing HYO/STO (0 0 1) with HYO/STO (0 1 1) systems, this work reports an insight into the orientation-dependent epitaxial relation, interplanar spacing, lattice constant and ferroelectric properties of o-HfO2 (1 1 1) films. Eventually, an ultra-thin ∼5.5 nm epitaxial single-crystal o-HYO (1 1 1) film with a large ferroelectric polarization of ∼35.9 μC cm−2 was obtained using LSMO/STO (0 1 1) substrate. These results are of great significance for the preparation and realization of high-quality epitaxial single-crystal ferroelectric o-HYO (1 1 1) ultra-thin films.
期刊介绍:
The journal offers a common reference and publication source for workers engaged in research on the experimental and theoretical aspects of crystal growth and its applications, e.g. in devices. Experimental and theoretical contributions are published in the following fields: theory of nucleation and growth, molecular kinetics and transport phenomena, crystallization in viscous media such as polymers and glasses; crystal growth of metals, minerals, semiconductors, superconductors, magnetics, inorganic, organic and biological substances in bulk or as thin films; molecular beam epitaxy, chemical vapor deposition, growth of III-V and II-VI and other semiconductors; characterization of single crystals by physical and chemical methods; apparatus, instrumentation and techniques for crystal growth, and purification methods; multilayer heterostructures and their characterisation with an emphasis on crystal growth and epitaxial aspects of electronic materials. A special feature of the journal is the periodic inclusion of proceedings of symposia and conferences on relevant aspects of crystal growth.