添加物對鍶鉍鉭鐵電薄膜顯微結構及其電性之影響

Abstract

本研究利用金屬有機分解法（MOD）在Pt/Ti/SiO2/Si基板上製備SrBi2Ta2O9薄膜，添加不同元素以取代SBT中之Ta元素。研究添加物對薄膜顯微結構及電性的影響，並探討其可能的原因。 由研究結果可知：V元素添加量在SrBi2(Ta2-xVx)O9(x = 0~0.25)範圍時有助於SBT薄膜性質的改善，包括較大Pr值，較小之漏電流。其主要因素應與薄膜微結構變化有關。在Ti元素的添加效應方面，Ti的添加對於SBT薄膜的電性有明顯的影響，其主要的效應應該與電荷平衡有關。Ti元素的適量添加有助於鐵電性質的提昇。W元素的添加效應與Ti元素有明顯的差異，薄膜的電性隨W元素的添加而有變差的趨勢。 再者，元素添加取代實驗中，許多不同條件下都會有二次相的生成，進而對薄膜性質造成不良的影響。所以在元素的選擇，添加比例及製程條件上都必須加以考量。以期藉由元素的添加，增益SBT薄膜的性質。

Metal-organic decomposition method (MOD) was used to prepare SrBi2Ta2O9 thin films on Pt/Ti/SiO2/Si substrate. The Ta substitution in SBT thin films with Ti4+ ,V5+ and W6+ ions was studied. The possible role of dopants in microstructure and electric properties of SBT thin films was investigated. Results showed that the substitution of V for Ta could improve electrical properties of SBT thin films, including higher remanent polarization and lower leakage current. This phenomenon is attributed to microstructure change of the thin films. In Ti-doped systems, the improvement in electric properties of SBT thin films was due to the compensation of charge balance. In the other hand, it was found that a reverse effect was observed for W-doped SBT thin films. Smaller Pr and large leakage current was detected. The observed poor electrical properties could be related to the formation of Bi-W oxide secondary phase. In addition, another secondary phase, composed of Bi and Ti was commonly observed in this SBT-based system, irrespectively of dopants type. However, the formation temperature of this secondary phase was also influenced by the dopants. The use of doping elements and doping quantity should be considered in order to improve properties of SBT thin films.