High-quality epitaxial LaNiO3 thin films on SrTiO3(100) and LaAlO3(100)

LaNiO3 thin films have been deposited by pulsed laser deposition on SrTiO3(100) and LaAlO3(100) substrates. The processing conditions have been investigated in order to optimize electrical resistivity, crystal quality, and surface morphology. Excellent properties are achieved at moderate substrate temperature and relatively low oxygen pressure, without the need for annealing. Thickness exerts an important influence on electrical transport, as the electrical resistivity increases quickly in films thicker than a few tens of nanometer. The surface of the films on LaAlO3 is very flat in all the studied thickness range, but the films on SrTiO3 develop a pattern of boundaries and even cracks as the thickness is higher. Below the critical thickness, high-quality epitaxial films with very smooth surface and low electrical resistivity are obtained under the optimum conditions of substrate temperature and oxygen pressure. The optimum processing conditions are different depending on the substrate, and control is especially critical in films deposited on SrTiO3.