DEPOSITION OF LANIO3 THIN-FILMS IN AN ATOMIC LAYER EPITAXY REACTOR

LaNiO3 thin films have been deposited in an atomic layer epitaxy (ALE) reactor, using La(thd)(3), Ni(thd)(2) and ozone as reactants, thereby proving the feasibility of the ALE technique to produce films of tern ary oxides. Depositions were made on Coming glass in the temperature r ange 150-450 degrees C. The growth conditions were studied and the gro wth rate showed a linear dependence on the number of cycles. At 400 de grees C the growth rate was 0.24-0.26 Angstrom per cycle. The growth r ate of the LaNiO, thin films was greatly influenced by the deposition temperature but in the temperature range 215-250 degrees C the growth saturated at 0.08 Angstrom cycle(-1) independent of the deposition tem perature, thus indicating an ALE window. As-deposited thin films were amorphous but crystallized when heated at 600 C. Simultaneously the co lour of the films changed from yellow-brown to black. Possible reasons for the colour changes are discussed. Resistivity measurements showed that the crystalline thin films were metallic, rho = (5-20) x 10(-6) Omega m. The amorphous thin films had resistivity values five orders o f magnitude larger, p > 3 Omega m. According to scanning electron micr oscopy (SEM) and atomic force microscopy (AFM), the films were homogen eous and dense. The surface roughness increased on crystallisation. X- Ray photoelectron spectroscopy (XPS) and magnetic susceptibility measu rements were employed in order to further characterize the amorphous a nd crystalline thin films.