Effects of\nNon-Stoichiometry and Strain on Ferroelectric\nProperties of CVD-Grown Bismuth Ferrite Films

Bismuth ferrite (BiFeO<sub>3</sub>, BFO) is a promising\nroom-temperature\nmultiferroic material but growing high-quality BFO thin films using\nchemical vapor deposition (CVD) has been challenging due to the limited\navailability of suitable precursors and the volatility of bismuth.\nIn this study, we successfully grew high-quality BFO thin films using\ndirect liquid injection CVD (DLI-CVD) with a solution mixture of iron\nacetylacetonate and triphenyl bismuth precursors dissolved in <i>N</i>,<i>N</i>-dimethylformamide. The films were deposited\non SrTiO<sub>3</sub>(001), DyScO<sub>3</sub>(110), and SrTiO<sub>3</sub>/Si(001) substrates at 600 °C. The Bi/Fe ratio in the films\nwas precisely controlled by adjusting the molar ratio of the precursors\nand strategically positioning substrates at optimal locations within\nthe deposition chamber. Additionally, the film strain state is established\nby lattice mismatch with the substrate and controlling the growth\nmode. We investigated the effects of nonstoichiometry, substrate-induced\nstrain, and crystalline mosaicity on the structural and ferroelectric\nproperties of BFO films. Additionally, we present the results of magnetic\nmeasurements for stoichiometric and iron-rich films. Our findings\ndemonstrate the potential of DLI-CVD for growing high-quality BFO\nfilms with superior electrical and magnetic properties.