Bi4Ti3O12 박막의 제작과 그 특성에 관한 연구

초록

A Bi4Ti3O12 (BIT) thin film is prepared by sol-gel method using acetate precursors and evaluated whether it could be applied to NVFRAM. The drying and the annealing temperature are 400℃ and 650℃, respectively and they are determined from the DT-TG analysis. The BIT thin film deposited on Pt/Ta/SiO2/Si substrate shows orthorhombic perovskite phase. The grain size and the surface roughness are about 100 nm and 70.2Å, respectively. The dielectric constant and the loss tangent at 10 kHz are 176 and 0.038, respectively, and the leakage current density at 100 kV/cm is 4.71μA/cm2. In the results of hysteresis loops measured at ±250 kV/cm, the remanent polarization (Pr) and the coercive field (Ec) are 5.92μC/cm2 and 86.3 kV/cm, respectively. After applying 109 square pulses of ±5V, the remanent polarization of the BIT thin film decreases as much as about 33% from 5.92μC/cm2 of initial state to 3.95μC/cm2.