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利用射频磁控溅射技术,在传导的钙钛矿型的LaNiO_3电极上生长了(Ba,Sr)TiO_3薄膜.为了研究生长温度对(Ba,St)TiO_3薄膜结晶程度的影响,沉积过程中选择了100℃-700℃的衬底温度.在300℃的较低生长温度时,薄膜由无定型相开始转变为多晶相;当生长温度增加到500℃以上时,薄膜呈现出高度的(h00)取向.利用扫描电子显微镜(SEM),可以看到在600℃时,薄膜的表面形貌光滑而且致密.另外,随着生长温度的提高,薄膜的相对介电常数(ε_r)因为结晶性的改善快速增大;在500℃以上时增加得比较小.薄膜在600℃以上时,其介电损耗低于0.02.同时研究了不同生长温度条件下薄膜的电容-电压特性,薄膜的调谐率随着结晶性的改善获得了极大的提高,这主要是薄膜介电常数增大的结果.

(Ba,Sr)TiO_3(BST) thin films were deposited on the conducting perovskite LaNiO_3 electrode by radio-frequency (rf) magnetron sputtering technique.The structure of BST films was investigated for the samples sputtered with substrate temperatures (Td)in the range of 100℃-700℃.The transition from amorphous phase to polycrystalline phase for the films Occurs at a low growth temperature of 300℃.When the growth temperature is above 500℃,BST films display (h00)preferred orientation.Using scanning electron microscopy (SEM),we find that the surface morphology of films is smooth and dense at 600℃.In addition,the relative dielectric constant(ε_r)increases rapidly with increasing growth temperature because of improved crystallinity and slowly increases above 500℃.The dielectric loss is lower than 0.02 when the growth temperature was above 600℃.The capacitance-voltage characteristics were also studied with different growth temperatures.The tunability increases largely with good crystallization.This can be attributed to increased dielectric constants.