高分子辅助沉积法制备LaNiO3外延导电薄膜

近年来LaNiO₃(LNO)作为铁电超晶格、超导异质结和催化剂材料引起了广泛关注。本研究采用简便、低成本的高分子辅助沉积法(Polymer Assisted Deposition, PAD), 在(001)取向的SrTiO₃(STO)单晶衬底上制备了导电性能优异的LNO外延薄膜, 并对其进行各种结构和电学表征。摇摆曲线半高宽为0.38°, 表明LNO薄膜结晶度良好。高分辨XRD的φ扫描进一步证实LNO薄膜在STO衬底上异质外延生长。原位变温XRD测试进一步表征了LNO薄膜的外延生长过程。结果表明, 聚合物分解之后金属阳离子在单晶基体上有序释放并外延结晶。XPS结果表明, 采用PAD制备的LaNiO₃薄膜不存在氧空位。薄膜表面光滑, 粗糙度为0.67 nm。在10~300 K温度区间内的变温电阻率表明LNO薄膜具有良好的导电性能。上述结果表明：PAD制备的LaNiO₃薄膜具有较好的综合性能, PAD在制备外延功能薄膜材料方面具有很大的潜力。

Preparation of Epitaxial Metallic LaNiO3 Thin Film by Polymer Assisted Deposition

LaNiO₃ (LNO), as a promising material in ferroelectric super lattices, super conductive heterostructures and catalysts has recently attracted great interest. Herein, a facile and low-cost polymer assisted deposition (PAD) method is established to prepare epitaxial LNO thin films on (001) orientated SrTiO₃ (STO) with excellent conductivity. Various structural and electrical characterizations of the film were investigated. The film has good crystallinity with a full-width at half-maximum value of 0.38° from the rocking curve for the (002) reflection. High resolution XRD φ-scans further confirmed the heteroepitaxial growth of LNO film on STO substrate. There are four peaks separated by 90°, showing that the LNO thin film is cubic-on-cubic grown on STO substrate. In-situ high temperature XRD measurement showed epitaxial growth of LNO thin film on STO substrate. Metal cations could be released orderly on the monocrystalline substrate and epitaxial crystallization occurs after decomposition of polymer. XPS results indicated that LaNiO₃ thin film fabricated by PAD was stoichiometric without oxygen vacancy. The atomic force microscopy analysis showed that the smooth surface with root-mean-square surface roughness was 0.67 nm. The resistivity as functions of temperature revealed that it has good conductivity from 10 K to 300 K. All results demonstrate that the LaNiO₃ thin films deposited by PAD have better comprehensive performance, indicating that PAD method has great potential for preparing epitaxial functional thin film materials.