Relationship Processing-Composition-Structure-Resistivity of LaNiO3 Thin Films Grown by Chemical Vapor Deposition Methods

Precision control of resistivity/conductivity of LaNiO3 (LNO) films is essential for their integration as electrodes in the functional heterostructures. This becomes possible if the relationship between processing parameters-composition-structure-resistivity is determined. LaNiO3 films were deposited by three different chemical vapor deposition methods using different precursor supply systems: direct liquid delivery, pulsed liquid injection, and aerosol generation. The possibilities to ameliorate the efficiency of precursor evaporation and of film growth were studied. The relationship between deposition conditions and composition was determined. Detailed analysis of the epitaxial growth of LNO films on cubic and trigonal substrates and the influence of the rhombohedral distortion on the microstructural quality was done. The resistivity of LaNiO3 films, grown by chemical vapor deposition, was mainly defined by microstructural defects and La/Ni composition. The high epitaxial quality LaNiO3/LaAlO3 films with nearly stoichiometric La/Ni ratio presented low resistivity, which was very close to that of bulk LaNiO3. Their annealing in oxygen atmosphere had little effect on the resistivity, which suggests a minor presence of oxygen vacancies in the as-grown films.