采用脉冲激光沉积法,在Pt/Ti/SiO2/Si基底上分别制备厚度为350nm的Ba0.5Sr0.5TiO3(BST)、Pb0.5Ba0.5TiO3 (PBT)和Pb0.5Sr0.5TiO3 (PST)薄膜并研究了它们的介电性质.XRD显示,在相同的制备条件下三者具有不同的择优取向,PST具有(110)择优取向,PBT具有(111)择优取向,而BST则是混合取向.SEM显示三者样品表面均匀致密,颗粒尺寸大约在50nm至150nm之间.PST与BST、PBT相比有更高的介电常数,在频率为10kHz时,分别为874、334和355,而损耗都较低,分别为0.0378、0.0316和0.0423,同时PST漏电流也是最小的.测量薄膜的C-V特性和铁电性能表明室温下BST呈现的是顺电相,PST和PBT则呈铁电相.本文也测量了薄膜在不同频率下的介电温度特性,BST、PBT和PST均表现出频率弥散现象,即随着频率的降低,居里温度降低而介电常数会升高.并测得BST和PST的居里温度分别为-75和150℃,而PBT的居里温度在250℃以上.本文研究表明:与BST相比较,PBT的介电常数与之相近,漏电流较大;而PST具有高介电常数,较小的漏电流和较大的电容-电压调谐度,在相关半导体器件中的应用将有很大的潜力.
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