摘要
采用湿化学工艺在硅衬底上成功地制备了结构致密、均匀且无龟裂的SrNb_xTi_(1-x)O_3薄膜。金属盐的冰醋酸溶液经回流再加入乙酸酐除去无机阴离子和结晶水,形成的金属醋酸盐与适当的络合剂形成的多配体络合物经部分水解生成的羟基化合物M(OH)_(n-x)(L)_x(L=C_4H_6O_6或AcAc,M=Sr或Ti或Nb)经羟基聚合形成SrNb_x-Ti_(1-x)O_3簇状溶胶。丙三醇抑制了羟基金属过度聚合,甲基纤维素(MCL)使SrNb_xTi_(1-x)O溶胶具有网状结构。SrNb_(0.1)Ti_(0.9)O_3(SNTO)凝胶薄膜经过650～750℃/30min退火形成假立方钙钛矿结构。应用XRD、SEM和TEM对薄膜结构和形貌进行表征。室温下SNTO薄膜的电阻率为54μΩ·cm,而在160K到室温之间薄膜电阻率随温度的变化遵从ρ=ρ_0+AT^2。分析结果表明:Nb^(5+)离子的施主掺杂改变了禁带宽度,实现了SrTiO_3的n-型半导体化。SNTO(100)/Pt/Ti/SiO_2/Si衬底上的Pb(Zr_(0.52)Ti_(0.48))O_3(PZT)薄膜的择优取向明显,较之于Pt/Ti/SiO_2/Si衬底上的PZT薄膜有良好的铁电性,其剩余极化强度也比PZT/Pt(111)/Ti/SiO_2/Si的大。
Homogeneous,crack-free SrNbxTit-xO3 films on （110） silicon substrates are successfully fabricated by sol-gel processing, The optimum route and conditions are systematically investigated. Sr（OAc）2 glacial acetic acid solution, being refluxed and reacted with acetylacetone （AcAc）, forms Sr （OAc） 2 （AcAc） x ; Ti （ OBu ） 4 molecule, being partially exchanged with AcAc, forms Ti（OAc）4-x （AcAc）x ;while Nb（OC2 H5 ）5 needs being changed into Nb（AcAc）2- （O4 C6 H6 ）2 by ligand exchange in glacial acetic acid under the anhydrous medium. All the hydrolizated species, partially hydrolyzed and polymerized by hydroxyl or oxygen, form SrNbxTi1-xO3 polymeric sol, Methyl cellulose （MCL） makes the SrNbxTi1-xO3 sol with polymeric structure and filming easily. SrNb0. 1 Ti0. 9 O3 （SNTO） films with cubic perovskite are subsequently formed after being annealed for 650-750℃/30min. XRD, SEM, and TEM are used for the structural characterization. The resistivity of the SNTO films at room temperature is 54μΩ· cm, and a particularly striking Te temperature dependence of the resistivity, from 160K up to room temperature, is observed. The results thus strongly suggest that the doped Nb5＋ modifies the width of the valence band located between upper part of the forbidden band and bottom of conducting band, and realizes n semi-conduction. SNTO（ 100）/Pt/Ti/SiO2/Si as substrate of Pb（Zr0. 52Ti0.48 ）O3 （PZT） compares with that of Pt/Ti/SiO2/Si has better ferroelectricity and Strong residual polarization.
