TEM study for self orientated LaNiO_3 film along 100

摘要

LaNiO_3 (LNO) is known as a candidate for oxide electrodes with perovskite type crystal structure which is suitable for lattice matching with conventional perovskite ferroelectrics, Pb(Zr,Ti)O_3 (PZT), BaTiO_3 (BTO), etc. We have been investigating thermal expansion effects of the LNO film with PZT/LNO/Si and BTO/LNO/Si structures, where ferroelectric and piezoelectric properties are enhanced by a compressive thermals stress impressed from the LNO layer to the ferrelectric films. The ferroelectric films also shows high [001] orientation owing to [100] orientation of the LNO film. In the present study, further investigation of the LNO films prepared on Si substrates by CSD method is made by transmission electron microscopy (TEM) in order to understand self-orientation along [ 100] perpendicular to the film plane which effectively leads orientation of PZT films prepared on the LNO film. The results obviously indicates that the 1 layer deposited LNO film has almost no orientation, whereas it shows tendency of orientation of [ 100] perpendicular to the film plane when the layer number increased.