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 degrees from the rocking curve for the (002) reflection. High resolution XRD phi-scans further confirmed the heteroepitaxial growth of LNO film on STO substrate. There are four peaks separated by 90 degrees, 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.

Automated summary

In this study, epitaxial LaNiO3 thin films with excellent conductivity were successfully prepared using a facile and low-cost polymer assisted deposition (PAD) method. Various structural and electrical characterizations showed that the films have good crystallinity, smooth surface, and stoichiometric composition. The results demonstrate that the PAD method has great potential for preparing epitaxial functional thin film materials.