Self-regulation of Bi/(Bi plus Fe) ratio in metalorganic chemical vapor deposition of BiFeO3 thin films

Metalorganic chemical vapor deposition (MOCVD) is one of the suitable techniques for practical applications of BiFeO3 films. To develop the potential of MOCVD as a device fabrication process, we investigated the relationship between the film and gas compositions, and the growth under highly oxidizing conditions using O-2 and O-3 gases. In the growth of epitaxial BiFeO3 thin films on SrRuO3-covered 4 degrees vicinal SrTiO3(001) at 620 degrees C, the self-regulation of the film composition was achieved for Bi and Fe precursor supply ratios between 62.1 to 78.5% under O-2 and 56.1 to 73.2% under 5 wt% O-3-mixed O-2 atmospheres. The leakage was very sensitive to the precursor supply ratio and oxidizing gas. 150-nm-thick MOCVD-BiFeO3 films grown using O-2+O-3 gas showed the minimum leakage current density of 2.3 x 10(-7) A/cm(2) at +1V. The highly oxidizing growth conditions using O-3 can suppress the leakage while precise composition control is required. (C) 2017 The Japan Society of Applied Physics