Mn掺杂BST薄膜的制备与表征

Preparation and Characterization on the Mn-Doped BST Thin Film

采用醋酸水溶液体系溶胶 -凝胶法制备了未掺杂和掺 Mn( )钛酸锶钡 (BST)薄膜。用这种方法 ,可在BST体系中容易地加入任何浓度的金属离子 ,并可在室温下长期保存。根据 X-射线衍射图 (XRD)和表面形貌 ,薄膜的晶化温度取为 6 5 0～ 75 0°C。根据掺 Mn BST的 Mn2 p3/2 X-射线光电子能谱 (XPS)图中 Mn2 p3/2 的峰位置 ,显示出薄膜中 Mn的价态与加入的 Mn( )离子价态相同。根据结合能的峰移 ,可以得到掺 Mn BST的费密能级降低0 .7e V。 I- V特性和介电特性测试表明 ,掺 Mn( ) BST的漏电流明显降低 ,相对的介电常数增加 ,损耗角正切降低0 .0 1。根据漏电性质、介电常数和损耗的关系 ,2 % (摩尔分数 )的 Mn掺杂的 BST薄膜适合于低频小信号 (2 V以下 ,约 5 0 0 k Hz)应用 ,而高浓度的 Mn掺杂适合于大信号较高频率 (1MHz以上 )应用。

Undoped and Mn(Ⅱ) doped barium strontium titanate (BST) thin films have been prepared by a 'water based' sol gel method.With this method,BST stock solution can be easily doped with any concentration of aqueous metal ion solution and can be stocked for more than a month at room temperature.The crystallization temperature of 650～750 °C is suitable for the films from the results of both the X ray diffraction (XRD) patterns and the surface topography.The Mn2p 3/2 X ray photoelectron spectra (XPS) pattern of the BST thin film shows that the valence state of the Mn doped BST has a same valance as the Mn(Ⅱ) dopant.Considering the peak shift of the binding energy,it is proposed that the fermi level of the Mn doped BST has been shifted down by 0 7 eV.The leakage current and dielectric loss of the BST films have been greatly reduced due to the Mn(Ⅱ) doping.