镧钛酸铅铁电薄膜的快速热处理研究

RAPID THERMAL ANNEALING OF LEAD LANTHANUM TITANATE FERROELECTRIC THIN FILMS

以不同热处理温度和保温时间的组合条件，对在不同种基片上制备的镧钛酸铅薄膜进行了快速热处理．主要研究了快速热处理工艺对薄膜相结构、化学组成、形貌的影响，并给出了典型样品的介电和铁电性能．实验结果表明：在较宽的热处理温度（５００～７５０℃）和保温时间（６～３６０ ｓ）范围内，都可得到无裂纹、均匀致密、晶粒大小约２０ ｎｍ的纯钙钛矿结构薄膜；不同的基片对薄膜的结晶有不同的影响；铂电极有利于薄膜结晶．在 ７００℃保温 ６０ ｓ的样品，１ｋＨｚ时介电常数约 ３００，介质损耗角正切不大于 ２％，剩余极化强度Ｐｒ＝５．２ μｃ／ｃｍ２，矫顽场强 Ｂｃ＝１１０ｋＶ／ｃｍ．

Lead lanthanum titanate fer roelectric thin films prepared on different kinds of sub-stractes are annealed by rapid thermal annealing process at various combinations of tempera-tures and holding times. Effects of the process on phase sturctures, chemical compositions and morphologies are principally investigated. Dielectric and ferroelectric properties of typical samples are shown. Experimental results show that within a wider range of temperatures (500-750℃) and holding times (6-360 s) ,free cracking,dence,homogeneous thin films of pure perovskite structure with grain size of about 20 nm can be obtained. Different kinds of substrates have different effects on crystalization. Platinum is favorable for crystalization of the thin films. Dielectric constant of the thin film annealed at 700 ℃ for 60 s is about 300, di- electric loss tangent is not more than 20% ,the remanent polarization is about 5. 2μc/cm2, and the coercive field is about 110 kV/cm at I kHz.