비휘발성 메모리 소자를 위한 PLZT(x/30/70) 박막에 대한 La 함유량 효과

초록

In this paper, the effects of La addition of PLZT(x/30/70) thin films prepared by sol-gel method are investigated for NVFRAM application. The tetragonality (c/a), the grain size, and the surface roughness of PLZT thin films decrease with an increase of La concentration. As the La concentration increases, the dielectric constants at 10 kHz increase from 450 to 600, while the loss tangent decrease from 0.075 to 0.025. Also, the leakage current density at 100 kV/cm decrease from 5.83×10-7 to 1.38×10-7 A/cm2. In the results of hysteresis loops measured at ± 170 kV/cm, the remanent polarization and the coercive field of PLZT thin films with La concentration from 0 to 10 mol% decrease from 20.8 to 10.5 μC/cm2 and from 54.48 to 32.12 kV/cm, respectively. After a fatigue measurement by applying 109 square pulses with ± 5V, the remanent polarizations of PLZT thin films with 0 and 10 mol% La concentration decrease about 64 and 42 % from initial state. In the results of retention measurement after 105 s, PLZT thin films with 0 to 10 mol% La concentration show that the remanent polarization is decreased about 43 % and 9 % from initial state, respectively.