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

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, O-2 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 (TMI) 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 TMI (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.