Substrate effect on electrical transport properties of RNiO₃ thin films prepared by pulsed laser deposition

Abstract

We report the structural and transport properties of RNiO₃ (R: Nd, Pr) thin films prepared by pulsed laser deposition over various substrates without high pressure annealing. An excimer laser KrF with wavelength of 248 nm was used for deposition. Various substrates such as single-crystal SrTiO₃ (100), LaAlO₃ (100) and Si (100) wafer are used for deposition of films to understand the effect of lattice mismatch on transport properties. Various parameters such as substrate temperature, O₂ pressure, laser fluence and deposition time are optimized to get good quality RNiO₃ films. The best quality films are found to be well textured with good crystalline properties. Well-defined first order metal–insulator phase transition (T_MI) was observed in the best quality NdNiO₃ films deposited on LaAlO₃. However, the PrNiO₃ films deposited on LaAlO3 show completely metallic behaviour throughout the temperature range with no T_MI (transition temperature). Metal–semiconductor transition has been observed in the PrNiO₃ films deposited on SrTiO₃. We try to explain this behaviour due to strain-induced growth of the films.