Mn-substituted BiFeO3(BFO) thin films were prepared by r.f. magnetron sputtering under an Ar/O2mixture of various deposition pressures at room temperature. The effects of the deposition pressure andannealing temperature on the crystallization and electrical properties of BFO films were investigated. X-raydiffraction patterns revealed that BFO films were crystallized for films annealed above 500oC. BFO filmsannealed at 550oC for 5 min in N2 atmosphere exhibited the crystallized perovskite phase. The (Fe+Mn)/Biratio decreased with an increase in the deposition pressure due to the difference of sputtering yield. The grainsize and surface roughness of films increased with an increase in the deposition pressure. The dielectricconstant of BFO films prepared at various conditions shows 127~187at 1kHz. The leakage current densityof BFO films annealed at 500oC was approximately two orders of magnitude lower than that of 550oC. Theleakage current density of the BFO films deposited at 10~30m Torr was about 5×10-6~3×10-2A/cm2 at 100kV/cm. Due to the high leakage current, saturated P-E curves were not obtained in BFO films. BFO film annealedat 500oC exhibited remnant polarization(2Pr) of 26.4µC/cm2 at 470kV/cm.

• 박상식 | Park, Sang-Shik