Yang Shihua,Xu JinBao,Gao Bo,Wang Lei,Chen Jing,Chen Xueying
Polycrystalline Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 (BCZT) thin films with (100) preferential and random orientation are prepared on the LaNiO 3 electrodes coated on Si substrates by chemical solution deposition process. The results show that the two types of films stabilize in the pure perovskite structure. The ferro-paraelectric phase transitions of two types of films occur at the temperature ranges of 280.2–297.8 K and 278.4–287.6 K, respectively. The dielectric constant, relaxation time and tunability of the random orientation film are smaller than those of the (100) preferential film but both almost have the similar leakage current characteristics. The mechanism associated with the change of the electrical properties of the thin films is also discussed.
The ferroelectric properties and fatigue resistance of 47(Ba 0.7 Ca 0.3 )TiO 3 –53Ba(Zr 0.2 Ti 0.8 )O 3 (BCZT) film can be enhanced by Tb modified and adding SrTiO 3 (STO) buffer layer using pulsed laser deposition(PLD) method. The 0.4 mol% Tb doped BCZT/STO(0.4Tb-BCZT/STO) film possesses optimal comprehensive electrical properties. Comparing with traditional BCZT film gown on Pt, the residual polarization( P r ), piezoelectric coefficient( d 33 *), permittivity( ε r ) of 0.4Tb-BCZT/STO film increase from 3.6 to 9.0 μC/cm 2 , 52 to 75 pm/V, 880 to 1210 and loss(tanθ) decrease from 0.028 to 0.017(10 4 Hz), respectively. During a high electric field, the degradation of P r is only 5.8% and the increase of E c is about 6.1% in 0.4Tb-BCZT/STO film after 10 9 switching cycles, which show the excellent fatigue resistance. The improved polarization and fatigue performances of film benefits from the reduced pinning influence with lower defect concentration based on a series of experiments and theoretical simulation. This work demonstrates the potential candidates of lead-free nonvolatile memory micro-devices applied in microelectronic industry.
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