Si基Bi3.25La0.75Ti3O12铁电薄膜的制备与特性研究

采用Sol-Gel工艺低温制备了Si基Bi3.25La0.75Ti3O12铁电薄膜.研究了退火温度对薄膜微观结构、介电特性与铁电性能的影响.500℃退火处理的Bi3.25La0.75Ti3O12薄膜未能充分晶化,晶粒细小且有非晶团聚,介电与铁电性能均较差.高于550℃退火处理的Bi3.25La0.75Ti3O12薄膜表面平整无裂纹,晶粒均匀,无焦碌石相或其他杂相,薄膜为多晶生长,具有较好的介电与铁电性能,4V电压下的漏电流密度低于2×10-8A/cm2.随退火温度升高,晶化程度的提升和晶粒尺寸的增大使薄膜的剩余极化增大而矫顽电场降低.600℃退火处理的Bi3.25La0.75Ti3O12薄膜显示了优于Bi4Ti3O12薄膜的铁电性能,其剩余极化Pr和矫顽电场Ec分别达到17.5μC/cm2和102kV/cm.     

Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管制备及存储特性

在溶胶-凝胶工艺获得高质量Bi4Ti3O12薄膜的基础上,制备了Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管. 研究了Si基Bi4Ti3O12薄膜的生长特性及其对铁电薄膜/硅的界面状态和铁电场效应晶体管存储特性的影响. 研究表明,在合理的工艺条件下可以获得具有较高c-轴择优取向的纯钙钛矿相Si基Bi4Ti3O12铁电薄膜并有利于改善Bi4Ti3O12/Si之间的界面特性; 顺时针回滞的C-V特性曲线和C-T曲线表明Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管具有极化存储效应和一定的极化电荷保持能力; 器件的转移(Isd-VG)特性曲线显示Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管具有明显的栅极化调制效应.     

Si基Bi4Ti3O12铁电薄膜的制备与特性研究

采用sol-gel工艺, 在分层快速退火的工艺条件下成功地制备了高质量Si基Bi_{4Ti3O12铁电薄膜. 研究了Si基Bi4Ti3O12薄膜的生长行为、铁电性能、C-V特性和疲劳特性. 研究表明: Si基Bi4Ti3O12薄膜具有随退火温度升高沿c轴择优生长的趋势; 退火温度通过影响薄膜的晶粒尺寸、生长取向和薄膜中载流子的浓度来改变Si基Bi关键词： sol-gel法 铁电薄膜 4Ti3O12')" href="#">Bi4Ti3O12 C-V特性}     

SrBi2Ta2O9/Bi4Ti3O12复合铁电薄膜的制备与特性研究

采用溶胶凝胶工艺在p-Si衬底上制备了SrBi2Ta2O9/Bi4Ti3O12复合铁电薄膜. 研究了SrBi2Ta2O9/Bi4Ti3O12复合薄膜的微观结构与生长行为、铁电性能和疲劳特性. 研究表明: Si衬底Bi4Ti3O12薄膜易于沿c轴择优生长,并有利于SrBi2Ta2O9/Bi4Ti3O12复合薄膜的生长.合理的SrBi2Ta2O9/Bi4Ti3O12厚度配比能获得较好的铁电性能和优良的抗疲劳特性,SrBi2Ta2O9/Bi4Ti3O12厚度配比为1∶3的复合薄膜的剩余极化强度和矫顽电场分别为8.1 μC/cm2 和 130 kV/cm,其无疲劳极化开关次数达1011以上.     

La掺杂对Bi4Ti3O12薄膜铁电性能的影响

利用Sol-Gel法在Pt/Ti/SiO2/Si衬底上制备出Bi4Ti3O12和Bi3.25La0.75Ti3O12薄膜,研究了La掺杂对Bi4Ti3O12薄膜的晶体结构、铁电性能和疲劳特性的影响,发现La掺杂没有改变Bi4Ti3O12薄膜的基本晶体结构,并且提高了Bi4Ti3O12铁电薄膜的剩余极化值和抗疲劳性能,对La掺杂改善Bi4Ti3O12铁电薄膜性能的机理进行了讨论.     

溶胶-凝胶法制备Sr2Bi4Ti5O18薄膜及其铁电性能研究

采用溶胶-凝胶法,在氧气氛中和层层晶化的工艺条件下,成功地制备了沉积在Pt/Ti/SiO2/Si(100)衬底上的铁电性能优良的Sr2Bi4Ti5O18(SBTi)薄膜,并研究了SBTi薄膜的微结构、表面形貌、铁电性能和疲劳特性.研究表明:薄膜具有单一的层状钙钛矿结构,且为随机取向;薄膜表面光滑,无裂纹,厚度约为725nm;铁电性能测试显示较饱和、方形的电滞回线,当外电场强度为275kV/cm时,其剩余极化2Pr和矫顽场2Ec分别为24.0μC/cm2和137.8kV/cm;疲劳测试发现薄膜经过4.4×1010次极化反转后,基本没有显示疲劳.     

La,V共掺杂的Bi_4Ti_3O_(12)铁电薄膜的溶胶-凝胶法制备及性能测试

采用溶胶-凝胶(sol-gel)工艺在Pt/TiO2/SiO2/p-Si(100)衬底上制备出Bi4Ti3O12(BIT)和Bi3.25La0.75Ti2.97V0.03O12(BLTV)铁电薄膜,研究了La,V共掺杂对BIT薄膜的晶体结构和电学性能的影响.BIT薄膜为c轴择优取向,BLTV薄膜为随机取向,拉曼光谱分析表明V掺杂降低了TiO6(或VO6)八面体的对称性,也增强了Ti—O键(或V—O键)杂化.BLTV薄膜的剩余极化Pr为25.4μC/cm2,远大于BIT薄膜的9.2μC/cm2,表现出良好的铁电性能.疲劳、漏电流测试显示BLTV薄膜具有优良的抗疲劳特性和漏电流特性,表明La,V共掺杂能有效地降低薄膜中的氧空位.     

Si基Bi3.25La0.75Ti3O12铁电薄膜的制备与特性研究

采用Sol-Gel工艺低温制备了Si基Bi_3.25La_0.75Ti₃O₁₂铁电薄膜.研究了退火温度对薄膜微观结构、介电特性与铁电性能的影响.500℃退火处理的Bi_3.25La_0.75Ti₃O₁₂薄膜未能充分晶化，晶粒细小且有非晶团聚，介电与铁电性能均较差.高于550℃退火处理的Bi_3.25La_{0.75 关键词： 铁电薄膜 3.25}La_0.75Ti₃O₁₂')" href="#">Bi_3.25La_0.75Ti₃O₁₂ Sol-Gel工艺     

Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管制备及存储特性

在溶胶-凝胶工艺获得高质量Bi₄Ti₃O₁₂薄膜的基础上 ，制备了Ag/Bi₄Ti₃O₁₂栅n沟道铁电场效应晶体管. 研 究了Si基Bi₄Ti₃O₁₂薄膜的生长特性及其对铁电薄膜/ 硅的界面状态和铁电场效应晶体管存储特性的影响. 研究表明，在合理的工艺条件下可以获 得具有较高c-轴择优取向的纯钙钛矿相Si基Bi₄Ti₃O₁₂ 铁电薄膜并有利于改善Bi₄Ti₃O₁₂/Si之间的界面特性; 顺时针回滞的C-V特性曲线和C-T曲线表明Ag/Bi₄Ti₃O_{12栅n沟道铁电场效应晶体管具有极化存储效应和一定的极化电荷保持能力; 器件的转移(I< sub>sd}-V_G)特性曲线显示Ag/Bi₄Ti₃O_{12栅n沟道铁电场效应晶体管具有明显的栅极化调制效应. 关键词： 铁电场效应晶体管 4}Ti₃O₁₂')" href="#">Bi₄Ti₃O₁₂ 存储 特性 溶胶-凝胶工艺     

应力对铋系铁电薄膜性能影响的研究进展

应力普遍存在于铁电薄膜中,是影响薄膜性能和薄膜电子器件可靠性的一个重要参数.本文系统介绍了本小组近年来所进行的应力对铋系铁电薄膜(Bi3.25La0.75Ti3O12,Bi3.15Nd0.85Ti3O12 和SrBi2Ta2O9)的铁电性能及与铁电存储有关的开关、疲劳性能等影响的研究.结果表明:张应力有利于增大薄膜的剩余极化和开关电荷量,而压应力却使得两者都降低.还发现:应力对薄膜的开关时间、矫顽场、疲劳性能等都有影响.其结果都与“应力作用下薄膜内铁电畴的重新取向“有关.     

Point defects on graphene on metals

Understanding the coupling of graphene with its local environment is critical to be able to integrate it in tomorrow's electronic devices. Here we show how the presence of a metallic substrate affects the properties of an atomically tailored graphene layer. We have deliberately introduced single carbon vacancies on a graphene monolayer grown on a Pt(111) surface and investigated its impact in the electronic, structural, and magnetic properties of the graphene layer. Our low temperature scanning tunneling microscopy studies, complemented by density functional theory, show the existence of a broad electronic resonance above the Fermi energy associated with the vacancies. Vacancy sites become reactive leading to an increase of the coupling between the graphene layer and the metal substrate at these points; this gives rise to a rapid decay of the localized state and the quenching of the magnetic moment associated with carbon vacancies in freestanding graphene layers.     

基于Matlab分析负荷对多联机IPLV的影响

多联机有其特殊的优点,但是不同部分负荷的组合对IPLV的影响仍需进一步研究。文中建立IPLV与部分负荷的相关公式,运用MATLAB软件分析不同卸载级负荷与IPLV的关系,从而确定不同部分负荷的最优组合。     

Note on duality on polarized symplectic manifolds

In this note we use some of the results of [3] to derive a general duality theorem for the cohomologies of foliated structures on a manifold. The result is applied to the special case of a symplectic manifold M on which the foliation is given by a complex polarization F in the sense of geometric quantization. We obtain, for example, a rigorous proof of the fact that for a smooth function ƒ on M whose Hamiltonian vector field leaves F invariant, the spectrum of the corresponding prequantization operator v(ƒ) coincides with the spectrum of its transpose, under the above duality. This latter result was obtained by Simms in [12] under certain hypotheses. Proofs of the validity of those hypotheses are now available in the literature; cf. [3] and [7].     

Space-charge effects on multipactor on a dielectric

Analyzes the effects of space charge shielding on the steady state of a multipactor discharge on a dielectric. Analytic methods are used to obtain an exact function for the potential in the discharge, assuming a Maxwellian distribution of emitted electrons. An equation for the amount of power deposited on the dielectric by the multipactoring electrons, for a given saturation level, is given. A simple method for obtaining the saturation level, for a given material, is obtained