杂质分布设计对钛酸锶钡薄膜结构和性能的影响

The influence of distribution of Na^+-dopant on the structure and dielectric properties of Ba_(0.25)Sr_(0.75)TiO_3 thin film

用溶胶-凝胶方法在Pt/Ti/SiO2/Si衬底上制备了Na+的不同浓度均匀掺杂和成分梯度掺杂(上梯度)钛酸锶钡(Ba0.25Sr0.75TiO3)薄膜.电性能测试表明随着均匀掺杂浓度的增加,薄膜介电常数和损耗都减小,而漏电流先减小(掺杂浓度小于2.5mol%时)后又逐渐增加.场发射扫描电镜分析表明,均匀掺杂浓度增加到2.5mol%后薄膜表面呈疏松多孔状结构,这可能是导致漏电流又逐渐增大的原因.Na+的上梯度掺杂避免了掺杂浓度增加到2.5mol%后薄膜生长过程中出现的孔洞现象,于是薄膜的综合电性能得到了进一步提高.深入、系统地分析了杂质不同分布方式对薄膜结构和性能有不同影响的原因.

Na^＋-doped and compositional graded doped Ba 0.25Sr 0.75TiO3 thin films were grown on Pt/Ti/SiO2/Si substrates by Sol-Gel technique.The dielectric properties of thin films were investigated as a function of Na^＋ doping level.It is revealed that with the increase of Na^＋ concentrations both the dielectric constant and the loss decrease continuously while the leakage current initially decreases（Na^＋〈 2.5mol%）and then increases.The increase of leakage current may be caused by the formation of porous structure which was confirmed by field emission scanning microscopy（FE-SEM）.The improvement of overall dielectric properties were achieved by using the compositional graded doping which results in a better microstructure in the film.