Crystallization behavior and ferroelectric properties of PbTiO_3/Ba_(0.85)Sr_(0.15)TiO_3/PbTiO_3 sandwich thin film on Pt/Ti/SiO_2/Si substrates

摘要

A PbTiO_3/Ba_(0.85)Sr_(0.15)TiO_3/PbTiO_3 (PT/BST15/PT) sandwich thin film has been prepared on Pt/Ti/SiO_2/Si substrates by an improved sol-gel technique.It is found that such films under rapid thermal annealing at 700 deg C crystallize more favorably with the addition of a PbTiO_3 layer.They possess a pure,perovskitephase structure with a random orientation.The polarization-electric field (P-E) hysteresis loop and current-voltage (I-V) characteristic curves reveal that a PT/BST15/PT film exhibits good ferroelectricity at room temperature.However,no sharp peak,only a weak maximum,is observed in the curves of the dielectric constant versus temperature.The dielectric constant,loss tangent,leakage current density at 20 kV/cm,remnant polarization,and coercive field of the PT/BST15/PT film are 438,0.025,1.3X10~(-6) Acm~(-2),2.46 muCcm~(-2),and 41 kVcm~(-1),respectively,at 25 degC and 10 kHz.The PT/BST15/PT film is a candidate material for high sensitivity elements for uncooled,infrared,focal plane arrays (UFPAs) to be used at near ambient temperature.