Ferroelectric properties of Bi_(3.25)La_(0.75)Ti_(3)O_(12) thin films prepared by sol-gel method

The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively.     

Ferroelectric properties of Bi<Subscript>4</Subscript>Zr<Subscript>0.5</Subscript>Ti<Subscript>2.5</Subscript>O<Subscript>12</Subscript> thin films prepared on LaNiO<Subscript>3</Subscript> bottom electrode by sol-gel method

The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant (ε) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect because of the BZT film's ferroelectric polarization.     

组合法制备Pb（ZrxTi（1-x））O3组分梯度薄膜

在无蒸馏和无惰性气氛保护的条件下,快速制备了用于组合合成Pb(ZrxTi1-x)O3薄膜的前驱溶液PT和PZ。采用组合法在Pt/Ti/SiO2/Si衬底上制备了一系列Pb(ZrxTi1-x)O3组分梯度薄膜。经XRD分析表明,薄膜具有钙钛矿结构,择优取向为(111)。SEM结果显示薄膜厚度在500nm左右。电滞回线的测试表明,下梯度薄膜PZT-654表现出良好的铁电性能,明显优于其它薄膜。PZT-654梯度薄膜的剩余极化强度Pr为38.4μC/cm2,矫顽场Ec为75.0kV/cm,有较大的极化偏移,Poffset为12.9μC/cm2,表现出梯度铁电薄膜的特性。     

在LaNiO3衬底上（Pb,La）TiO3铁电薄膜的制备和研究

首先通过金属有机化合物热分解(MOD)法在Si(100)基片上制备出LaNiO3(LNO)薄膜,再通过溶胶-凝胶(sol-gel)法,在LNO/Si(100)衬底上制备出(PbxLa1-x)TiO3(PLT)铁电薄膜。经XRD分析表明,LNO薄膜具有(100)择优取向的类钙钛矿结构,PLT/LNO/Si薄膜具有四方相钙钛矿结构,同时以(100)择优取向。最后对薄膜的介电性和铁电性进行了测试,发现薄膜介电常数适中,铁电性良好。     

溶胶-凝胶法制备（Nd,Bi）_4Ti_3O_（12）铁电薄膜

采用溶胶-凝胶法在Pt/Ti/SiO2/Si基片上制备了（Nd,Bi）4Ti3O12薄膜。将薄膜于空气中分别进行每1层、每2层、每3层500℃预退火10 min,最后于氮气氛中680℃退火30 min。结果表明：预退火工艺对薄膜的结构和铁电性能都有影响：每一层预退火处理的薄膜具有较大的剩余极化值和最小的矫顽场（2Pr=47.8μC/cm2,2Ec=254 kV/cm）。所有薄膜都呈现良好的抗疲劳特性。     

异质结薄膜的铁电、磁性能及漏电流研究

采用溶胶凝胶方法在Si（100）衬底上生长了SrBi2Ta2O9/LaNiO3 (SBT/LNO)异质结薄膜,其中SrBi2Ta2O9薄膜呈高度（115）取向.测量了不同退火温度下异质结的电滞回线和漏电流密度,结果表明,700 ℃下退火的薄膜剩余极化值最高,漏电流最低,且表现出弱的室温铁磁行为.漏电流机理分析表明薄膜界面为欧姆接触.     

Effect of La Doping on Microstructure and Ferroelectric Properties of Bi4Ti3O12 Thin Films Prepared by Sol-gel Method

The Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films were prepared on the Pt/Ti/SiO2/Si substrate using the sol-gel method. The effect of La doping on the microstructure and ferroelectric properties of Bi4Ti3O12 films were investigated. Both the Bi4Ti3O12 and Bi3.25La0.75Ti3O12 thin films exhibited typical bismuth layered perovskite structure. The 2Pr (remanent polarization) value of Bi3.25La0.75Ti3O12 thin films is 18.6 Μc/cm2, which is much larger than that of Bi4Ti3O12 thin films. And the Bi3.25La0.75Ti3O12 films show fatigue-free behavior, while the Bi4Ti3O12 thin films exhibit the fatigue problem. The mechanism of improvement of La doping was discussed.     

在LaNiO_3衬底上（Pb,La）TiO_3铁电薄膜的制备和研究

首先通过金属有机化合物热分解（MOD）法在Si（100）基片上制备出LaNiO3（LNO）薄膜,再通过溶胶-凝胶（sol-gel）法,在LNO/Si（100）衬底上制备出（PbxLa1-x）TiO3（PLT）铁电薄膜。经XRD分析表明,LNO薄膜具有（100）择优取向的类钙钛矿结构,PLT/LNO/Si薄膜具有四方相钙钛矿结构,同时以（100）择优取向。最后对薄膜的介电性和铁电性进行了测试,发现薄膜介电常数适中,铁电性良好。     

SrBi2Ta2O9/LaNiO3异质结薄膜的铁电、磁性能及漏电流研究

采用溶胶凝胶方法在Si（100）衬底上生长了SrBi2Ta2O9/LaNiO3（SBT/LNO）异质结薄膜,其中SrBi2Ta2O9薄膜呈高度（115）取向.测量了不同退火温度下异质结的电滞回线和漏电流密度,结果表明,700℃下退火的薄膜剩余极化值最高,漏电流最低,且表现出弱的室温铁磁行为.漏电流机理分析表明薄膜界面为欧姆接触.     

Ferroelectric properties of Bi3.4Ho0.6Ti3O12 thin films prepared by sol-gel method

We have prepared the Ho-substituted bismuth titanate (Bi_3.4Ho_0.6Ti₃O₁₂, BHT) thin films on Pt/Ti/SiO₂/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm² and 376.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 310 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×10⁹ switching cycles at 1 MHz frenquency, and the BHT film shows good insulating behavior according to the test of leakage current. Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309)     

Influence of annealing time on the microstructure and properties of Pb(Zr0.53Ti0.47)O3 thin films

The PZT thin films were prepared on (111)- Pt/Ti/SiO2/Si substrates by sol-gel method, and lead acetate [Pb(CH3COO)2], zirconium nitrate [Zr(NO3)4] were used as raw materials. The X-ray diffractometer (XRD) and scanning electron microscopy (SEM) were used to characterize the phase structure and surface morphology of the films annealed at 650 ℃ but with different holding time. Ferroelectric and dielectric properties of the films were measured by the ferroelectric tester and the precision impedance analyzer, respectively. The PZT thin films were constructed with epoxy resin as a composite structure, and the damping properties of the composite were tested by dynamic mechanical analyzer (DMA). The results show that the films annealed for 90 minutes present a dense and compact crystal arrangement on the surface; moreover, the films also achieve their best electric quality. At the same time, the largest damping loss factor of the composite constructed with the 90 mins-annealed film shows peak value of 0.9, higher than the pure epoxy resin.     

衬底效应对LiTaO3薄膜制备的影响

用溶胶凝胶法在N型硅、P型硅、石英、铂、镍衬底上制备了钽酸锂(LiTaO3)薄膜,用XRD和SEM对钽酸锂薄膜性能参数进行了表征;发现掺杂少量环氧树脂能提高钽酸锂薄膜的均匀性,改善薄膜与衬底的粘附性;研究了衬底效应与薄膜厚度的关系,薄膜厚度超过0.2 μm,Ni衬底的XRD峰值强度几乎不再出现,说明衬底对薄膜初始结晶取向有重要影响;利用不同衬底上生长钽酸锂薄膜,XRD研究结果表明:N型硅、P型硅、石英衬底上只能制备多晶钽酸锂薄膜,铂衬底上制备的钽酸锂薄膜在(012)晶向有强大的择优取向性,镍衬底上制备的钽酸锂薄膜有更好的C轴择优取向性,C轴择优取向系数可达0.082。     

Synthesis and Characterization of (PEO)_x~-(V_(0.85)Mo_ (0.15)_2O_5 Nanocomposite Films

1　IntroductionSomeinorganiclayeredcompounds ,suchasMoO3 andV2 O5,belongtoarapidlygrowingfieldofcontempo raryresearchinterest,becausetheycanbeintercalatedbyavarietyofalkaliions (Li+ ,Na+ ,etc .) ,atomsorlargermoleculestoformintercalationhost guestcompounds ,whichareexpectedtobepromisingcandidatematerialsforcathodesofsecondaryLibatteriesandelectrochromicdevices[1] .Polymer layeredoxidenanocompositesareat tractingmuchattentionduetotheirspecialstructureaswellassuperiorelectrical,electrochemical…     

纳米晶Ba（Zr0．2Ti0．8）O3薄膜的外延生长与介电特性

用脉冲激光沉积工艺在半导体（001）SrTiO3：ω（Nb）=1．0％单晶基片上,外延生长出Ba（Zr0.2Ti0.8）O3（简称BZT）介电薄膜．在650℃原位退火10min,薄膜为（001）外延生长的晶粒．薄膜的晶化特征与表面形貌用薄膜X-ray衍射仪和原子力显微镜测量完成．BZT薄膜（002）峰的半峰宽只有0．72°,说明薄膜晶化良好;薄膜的平均晶粒为90nm,表面均方根粗糙度为4．3nm,说明薄膜表面平整．在室温、100kHz和500kV／cm条件下,BZT的最大介电常数和调谐百分率分别达到317和65％．     

Dynamic dam-reservoir interaction analysis including effect of reservoir boundary absorption

The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively.     

纳米针状金刚石膜的制备

利用高功率微波等离子体化学气相沉积方法在硅衬底上沉积了多晶金刚石薄膜,然后利用电子束蒸发方法在金刚石薄膜表面上沉积了5 nm厚的Pt薄膜.利用Pt的自组织化效应,再通过氢等离子体照射、氧等离子体刻蚀、王水处理等手段,使金刚石薄膜表面形成了纳米针.利用拉曼光谱和扫描电子显微镜(SEM)表征金刚石薄膜的结构,拉曼光谱显示在1 315 cm^-1处出现纳米金刚石特征峰,SEM显示纳米针均匀地直立在金刚石薄膜表面,每平方厘米大约含有10⁸个纳米针,纳米针的平均高度约为1 μm.     

Fabrication of metal suspending nanostructures by nanoimprint lithography (NIL) and isotropic reactive ion etching (RIE)

We report herein a rational approach for fabricating metal suspending nanostructures by nanoimprint lithography (NIL) and isotropic reactive ion etching (RIE). The approach comprises three principal steps: (1) mold fabrication, (2) structure replication by NIL, and (3) suspending nanostructures creation by isotropic RIE. Using this approach, suspending nanostructures with Au, Au/Ti or Ti/Au bilayers, and Au/Ti/Au sandwiched structures are demonstrated. For Au nanostructures, straight suspending nanostructures can be obtained when the thickness of Au film is up to 50 nm for nano-bridge and 90 nm for nano-finger patterns. When the thickness of Au is below 50 nm for nano-bridge and 90 nm for nano-finger, the Au suspending nanostructures bend upward as a result of the mismatch of thermal expansion between the thin Au films and Si substrate. This leads to residual stresses in the thin Au films. For Au/Ti or Ti/Au bilayers nanostructures, the cantilevers bend toward Au film, since Au has a larger thermal expansion coefficient than that of Ti. While in the case of sandwich structures, straight suspending nanostructures are obtained, this may be due to the balance of residual stress between the thin films. Supported by the National Natural Science Foundation of China (Grant No. 20573002) and the Major State Basic Research Development Program of China (973Pprogram) (Grant No. 2001CB6105)     

Crystallization and Electrical Properties of （Ba0.4Pb0.3）Sr0.3TiO3 Thin Film by Pulsed Laser Deposition

（Ba0.4Pb0.3）Sr0.3TiO3 thin films were fabricated via pulsed laser deposition （PLD） technique on Pt/TiO2/SiO2/Si substrate. The crystallization of the films was characterized by XRD and FSEM, and the experimental results suggested deposition parameters, especially the deposition temperature was the key factor in forming the perovskite structure. The dielectric properties of the film deposited with optimized parameters were studied by an Agilent 4294A impedance analyzer at 1 MHz. The dielectric constant was 772, and the loss tangent was 0.006. In addition, the well-shaped hysteresis loop also showed that the film had a well performance in ferroelectric. The saturated polarization P, remnant polarization Pr and coercive field E were about 4.6 μC/cm2, 2.5 μC/cm2 and 23 kV/cm （the coercive voltage is 0.7 V）, respectively. It is suggested the film should be a promising candidate for microwave applications and nonvolatile ferroelectric random access memories （NvFeRAMs）.     

Effect of Bi content in precursor solutions on microstructure and ferroelectric properties of bismuth cerium titanate thin films

Sol-gel derived bismuth cerium titanate (BCT) thin films with different Bi contents in precursor solutions were deposited on the Pt/Ti/SiO₂/Si substrates. The effect of Bi content in the precursor solutions on the microstructure and ferroelectric properties of the films was investigated. It is found that with Bi content increasing from 90% to 110% of the nominal value in the precursor solutions, the dissipation factor and leakage current density of the BCT films obtained decrease, while the grain sizes, dielectric constant and remanent polarizations (2Pr) increase, and concurrently, a Bi-deficient phase of Bi₂Ti₂O₇ gradually disappears. The film prepared from solution with 110% of the nominal Bi content exhibits pure Bi-layered Aurivillius polycrystalline phase, and the 2Pr value and coercive field value are 67.1 μC/cm² and 299.7 kV/cm, respectively. Their dielectric constant and the dissipation factor are about 172 and 0.033 at 1 kHz, respectively. Moreover, this film shows no polarization fatigue after 4.46×10⁹ switching cycles. Supported by the Hubei Province Natural Science Foundation (Grant No. 2007ABA309)     

Si(111)和Si(100)衬底上磁控反应溅射制备AlN薄膜

采用射频磁控反应溅射法在Si(111)和Si(100)两种衬底上制备了AlN薄膜,用X射线衍射(XRD)对AlN薄膜进行了表征,研究了衬底Si(111)、Si(100)取向以及N2百分比对AlN(002)薄膜c-轴择优取向的影响。实验结果表明,Si(100)较适合生长c-轴择优取向AlN薄膜,而且N2百分比为40%时,AlN薄膜的c-轴取向最好,具有尖锐的XRD峰,此时对应于AlN(002)晶向。计算了(002)取向AlN和两种Si衬底的失配度,Si(111)面与AlN(002)面可归结为正三角形晶系之间的匹配,失配度为23.5%;而Si(100)面与AlN(002)面可归结为正方形晶系与正三角形晶系之间的匹配,失配度为0.8%,可以认为完全共格。理论分析和实验结果相符。