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1、电子科技大学博士学位论文从而建立了铁电薄膜的电压非线性模型。最后，利用文献的数据和曲线对模型进行验证，模拟得到的曲线与实验得到的曲线变化趋势基本一致，表明该模型可以较好地解释铁电材料(包括陶瓷和薄膜)的电压非线性特性及其随晶粒大小、膜厚、界面厚度等尺度变化的规律。对薄膜型介质移相器的设计、制作和测试进行了研究。采用ADS和HFSS软件进行仿真，设计出了分布式电容负载型铁电薄膜介质移相器的电路结构和各部分的尺寸;采用改进的剥离工艺，制作出了电极线条整齐的铁电薄膜介质移相器;采用矢量网络分析仪，在频率为35GHz、
2、控制电压为40V条件下，测得介质移相器的移相度为1800，插损为9.7dBo关键词:钦酸银钡，薄膜，介电非线性，模型，电畴，介质移相器电子科技大学博士学位论文ABSTRACTBariumstrontiumtitanate(Ba.Sr1_,Ti031shortforBS刀thinfilmsarepotentialmaterialsfortheapplicationsofmicrowavedevicessuchasdielectricphaseshiftersandtunablefiltersduetotheirh
3、ighdielectricnonlinearity,lowleakagecurrentandadjustingCurietemperature.ThemicrostructuresanddielectricpropertiesofBa.Sr,_xTi03(x=0.45--0.9)ceramics,filmthicknessuniformity,microstructuresandsizeefectondielectricnonlinearitiesofBSTfilms,modelfordielectricnon
4、linearityofferroelectricfilms,designandfabricationofphaseshifterswereinvestigated.Moreover,thereareaseriesofresultsasfollows:Onconditionthatthecenterofthesubstrateisnotcoincidentwiththatofthetarget,themagnetronsputeringsystemwasstudied.Undertheconditionsofpl
5、anetarymovementofasubstrateunderneathamagnetronsputercathode,amodelontherelationbetweenthefilmthicknessandtheparameters,suchasrotationspeed,revolutionspeedandthedistancefromtargettosubstrate,wasobtained.TherelativefilmthicknessdistributioncanbeexpressedbyT=工
6、d(x,y)ds=工d(}(t),V(t))V}"(t)+W'2(t)-dt.Itisfoundthattherelativedeviationoffilmthicknessdistributionis2.8%withinadiameterof(b100mmwhentheratiooftherotationspeedtorevolutionspeedandthedistancefromtargettosubstrateare5.3and72mm,respectively.Thespeciesandsizesof
7、domainsinBSTthinfilmswereinvestigatedbypiezoresponseforcemicroscopy(PFM).Theresultsshowthatthereare900domains.Itisfoundthatthecriticalgrainsizefromamulti-domaintoasingle-domainisabout31nm.ThesizeefectsonnonlinearityofBSTthinfilmswereinvestigatedandtheresults
8、showthatthegrainsizeandfilmthicknessplayanimportantroleonnonlinearityofferroelectricfilms.ThedielectricconstantandthetunabilityofBSTthinfilmsincreaseasthegrainsizeand/orfilmthicknessincrease.The
