脉冲激光淀积高温超导薄膜

１９８７年贝耳实验室首次用脉冲准分子激光制备出高温超导薄膜以后，脉冲激光淀积技术获得了长足的发展，现在已成为最好的薄膜制备技术之一．文章简要介绍了用脉冲激光淀积技术制备高温超导薄膜的原理、特点及发展情况．     

脉冲激光淀积BaTiO3薄膜的介电与铁电特性

用脉冲激光淀积方法在SrTiO₃衬底上制备了BaTiO₃/YBa₂Cu₃O_7-δ（铁电/超导）双层膜，X射线分析表明BaTiO₃薄膜是高度c取向的．对BaTiO₃薄膜的介电和铁电性能进行了实验研究．观察到铁电薄膜特有的电滞线和蝶型C-V曲线，薄膜呈现出较好的铁电性，在铁电随机存储等领域有重要的应用前景 关键词：     

BIT/PLZT/BIT多层铁电薄膜结构设计及制备的实验研究

为了有效阻止锆钛酸铅镧(PLZT)与半导体界面发生反应和互扩散,根据锆钛酸铅镧和钛酸铋(B IT)各自的铁电性能,提出了一种新的设计思想———多层铁电薄膜.采用脉冲准分子激光淀积(PLD)方法制备了B IT/PLZT/B IT多层铁电薄膜.采用Sawyer-Tower电路测量,其剩余极化强度Pr=34μC/cm2,矫顽场Ec=40 kV/cm.这种结构吸收了锆钛酸铅镧和钛酸铋的优点,提高了铁电薄膜的铁电性能.     

用脉冲激光淀积制备具有光滑表面的A-轴取向YBa2Cu3O7薄膜

我们采用脉冲激光淀积方法在(100)SrTiO3基底上制备了a-轴取向外延的YBa2Cu3O7-x薄膜.通过采用活性氧,降低氧压和淀积速率,制备出了Tc超过80K、表面平均粗糙度为4.43nm的薄膜.X-射线衍射谱表明,实验得到的YBa2Cu3O7-x外延薄膜是高度A-轴取向的.     

Au/PZT/BIT/p-Si异质结的制备与性能研究

采用脉冲激光沉积(PLD)工艺,制备了以Bi₄Ti₃O₁₂(BIT)为过渡阻挡层的Au/PZT/BIT/p-Si异质结.研究了BIT铁电层对Pb(Zr_0.52Ti_0.48)O₃(PZT)薄膜晶相结构、铁电及介电性能的影响,对Au/PZT/BIT/p-Si异质结的导电机制进行了讨论.氧气氛530℃淀积的PZT为多晶铁电薄膜,与直接淀积在Si基片上相比,加入BIT铁电层后PZT铁 关键词： 铁电薄膜 异质结构 脉冲激光沉积(PLD)     

XeCl（308nm）脉冲准分子激光淀积类金刚石薄膜

利用ＸｅＣｌ（３０８ｎｍ）脉冲准分子激光淀积技术在功率密度５×１０８Ｗ／ｃｍ２、室温、真空度１０－３Ｐａ的条件下，制备出不含氢成分的类金刚石薄膜，研究了类金刚石薄膜的特性及其随制备工艺条件的变化规律。研究了激光诱导的碳等离子体发射光谱，探讨了类金刚石薄膜的形成机理。     

PLD法制备PZT-YBCO结构的铁电薄膜的研究

本文利用脉冲准分子激光在LaAlO3单晶基片上淀积了YBCO和Zr/Ti为94/6的PZT铁电薄膜,并通过高频溅射将Pt蒸镀在PZT薄膜上作为上电极;用X射线衍射表征了该多层膜的晶相结构,测量了PZT的铁电性能和介电特性,讨论了PZT/YBCO薄膜的制备工艺,以及工艺条件对晶相结构和薄膜性能的影响.     

激光等离子体淀积硅膜

本工作研究了低温、低压下硅薄膜的激光淀积过程,获得均匀性好,平方厘米量级的多晶和非晶态薄膜。仔细测量了淀积过程的最佳条件,在380℃基片温度做得多晶膜。利用有共振吸收的光学击穿以及气体被击穿后产生爆炸波导致高能Si原子产生的模型,讨论了激光等离子体CVD动力学过程。发现TEACO₂激光击穿SiH₄,以及诱发的爆炸波对硅膜生长有重要作用。理论算得的硅膜生长面积和晶态结构与实验定性符合。 关键词：     

激光蒸发淀积高Tc超导薄膜

本文简要介绍激光蒸发淀积高Ｔｃ超导薄膜技术的基本原理．主要工艺特点，各种激光器在制备高Ｔｃ超导薄膜中的应用及所取得的重要成果．     

脉冲准分子激光淀积薄膜的实验研究

 利用两种脉宽(30ns，500fs)的KrF准分子激光展开了淀积类金刚石薄膜的实验研究，并且成功地制备了大面积不含氢成分的HF-DLC薄膜，运用时空分辨的等离子体发射光谱诊断系统和离子探针系统研究了等离子体特性对薄膜性能的影响。尝试了利用准分子激光制备非晶硅薄膜，研究了实验参数对非晶硅薄膜制备的影响，并分析了制备具有良好电学和光学性能的非晶硅薄膜的条件。     

The coexistence of ferroelectricity and ferromagnetism in Mn-doped BaTiO3 thin films

Due to the fault of the first author, this article entitled “The coexistence of ferroelectricity and ferromagnetism in Mn-doped BaTiO3 thin films”, published in “Chinese Physics B”, 2011,Vol.20, Issue 12, Article No. 127701, has been found to copy from the article entitled“Decisive role of oxygen vacancy in ferroelectric versus ferromagnetic Mn-doped BaTiO3 thin films”, published in “Journal of Applied Physics”, 2011,Vol.109, Issue 8, article No. 084105. So the above article in “Chinese Physics B” has been withdrawn from the publication.<     

高压退火对0.65PMN-0.35PT薄膜结构、形貌及电学性能的影响

利用射频磁控溅射技术在LaNiO₃/SiO₂/Si(100)基底上制备了厚 度约为250 nm的0.65PMN-0.35PT(PMN-PT)薄膜. 研究高压氧氛围退火方式对PMN-PT薄膜晶体结构、形貌以及电学性能的影响. 经过XRD测试发现,在高压氧气氛围中, 温度为400℃下退火后的PMN-PT薄膜具有纯的钙钛矿相结构, 具有完全的(100)择优取向, 且衍射峰尖锐, 表明经过高压退火后的薄膜结晶极为充分. SEM表面形貌测试结果显示, 经高压退火处理的PMN-PT薄膜表面呈现出棒状或泡状的形貌. 铁电性能测试表明: 氧气氛围压强4 MPa, 退火时间4h的PMN-PT薄膜样品具有较好的铁电性能, 其剩余极化强度P_r达到10.544 μC/cm², 且电滞回线形状较好, 但漏电流较大, 这可能是由于其微结构所导致.同时介电测试发现: PMN-PT薄膜样品具有极好的介电性能, 其在1 kHz下测试的介电常数ε_r达到913, 介电损耗tgδ 较小, 仅为0.065. 关键词： 射频磁控溅射 高压退火 0.65PMN-0.35PT 介电     

溶胶-凝胶法制备BaTiO3/SrTiO3多层膜的介电增强效应

采用溶胶凝胶法,在PtTiSiO2Si衬底上逐层制备了BaTiO3SrTiO3多层膜.从多层膜的XRD图可看出明显的双峰,分别对应为BaTiO3和SrTiO3的特征峰,表明样品已形成了多层膜结构.与同厚度的Ba05Sr05TiO3单层膜比较,BaTiO3SrTiO3多层膜的介电系数得到了明显的增强,在频率为10kHz时,周期为66nm的BaTiO3SrTiO3多层膜相对于同厚度的Ba05Sr05TiO3薄膜的介电系数从245增强到595,而损耗依然保持较低,分别为0029和0033.研究同时表明,BaTi 关键词： 溶胶-凝胶法 多层膜 介电增强     

Effect of oxygen pressure on structure and properties of Bi1.5Zn1.0Nb1.5O7 pyrochlore thin films prepared by pulsed laser deposition

The Bi₂O₃-ZnO-Nb₂O₅ (BZN) cubic pyrochlore thin films were prepared on Pt/TiO₂/SiO₂/Si(1 0 0) substrates by using pulsed laser deposition process. The oxygen pressure was varied in the range of 5-50 Pa to investigate its effect on the structure and dielectric properties of BZN thin films. It is found that oxygen pressure during deposition plays an important role on structure and other properties of BZN films. The BZN films deposited at temperature of 650 °C and at O₂ pressure of 5 Pa have an amorphous BZN and Nb₂O₅ phases but exhibits a cubic pyrochlore structure with a preferential (2 2 2) orientation when the oxygen pressure increases to 10 Pa. Dielectric constant and loss tangent of the films deposited at 10 Pa are 185 and 0.0008 at 10 kHz, respectively. The dielectric tunability is about 10% at a dc bias field of 0.9 MV/cm.     

Structural and electric properties of Bi2Zn2/3Nb4/3O7 thin films prepared by pulsed laser deposition

Bi₂Zn_2/3Nb_4/3O₇ thin films were deposited on Pt/TiO₂/SiO₂/Si(100) substrates under an oxygen pressure of 10 Pa by pulsed laser deposition. The substrate temperature varied from 500 ^°C to 750 ^°C. Effects of substrate temperature on the crystallinity, microstructure, and electric properties of Bi₂Zn_2/3Nb_4/3O₇ thin films have been systematically investigated. Bi₂Zn_2/3Nb_4/3O₇ thin films are amorphous in nature at a substrate temperature of 500 ^°C. With increase of substrate temperature to 550 ^°C, thin films begin to crystallize. At higher temperature of 750 ^°C, Bi₂O₃ phase can be detected in thin films. However, the crystallized thin films exhibit a cubic pyrochlore structure, not a monoclinic zirconolite structure, which is probably attributed by the composition deviation from the stoichiometric ratio. The resultant Bi₂Zn_2/3Nb_4/3O₇ thin films exhibit the character with high dielectric constant and low loss tangent. The dielectric constant gradually increases with the substrate temperature and reaches a maximum at 700 ^°C. The dielectric constant and loss tangent of the thin films deposited at 700 ^°C are 152 and 0.002 at 10 kHz, respectively. With further increase of substrate temperature to 750 ^°C, the dielectric constant decreases to 128. However, the tunability of the resultant thin films disappears, and the temperature coefficients are positive, which implies a more ordered structure in thin films.     

Crystallographic orientation dependence of the dielectric constant in polymorphic BaNb<Subscript>2</Subscript>O<Subscript>6</Subscript> thin films deposited by laser ablation

Well-crystallized barium metaniobate (BaNb₂O₆) thin films were fabricated on fused quartz substrates by pulsed laser deposition. The influence of substrate temperature and oxygen pressure on the crystal structure and preferred orientation were studied to understand the growth mechanism of BaNb₂O₆ thin films. The films formed at 600 °C at an oxygen pressure of 100 mTorr exhibited predominantly the orthorhombic (040) orientation, and turned to the orthorhombic (230) orientation at 800 °C. It was found that (220)-oriented hexagonal thin films were formed at 600 °C at an oxygen pressure less than 50 mTorr. The dielectric constant of the BaNb₂O₆ thin films was measured by scanning microwave microscopy (SMM). Preferentially (230)-oriented orthorhombic and (220)-oriented hexagonal BaNb₂O₆ thin films were shown to have significantly enhanced dielectric constants of 47.8 and 56.7, respectively. This could be attributed to the dependence of the dielectric constant on crystallographic orientation. PACS 77.55.+f; 77.84.Dy     

Dielectric properties of multilayered SrTiO3 thin films with graded oxygen vacancy concentration

SrTiO₃ (STO) thin films were homo-epitaxially grown on Nb-doped STO substrates at varying oxygen pressures, and the effect of oxygen vacancy concentration on the dielectric properties of the STO thin films was studied and is presented herein. Although the STO thin films with low oxygen vacancy concentration demonstrated low zero-bias permittivity, low dielectric tunability, and high dielectric dissipation, the STO thin films, however, could withstand a large electric field. While the STO thin films with high oxygen vacancy concentration exhibited reduced dielectric loss and high dielectric tunability, they exhibited a low breakdown electric field. In order to make use of the respective advantages of the STO thin films with different oxygen vacancy concentrations, a trilayered structure was obtained by varying the oxygen pressure during deposition and combining one thin STO layer with large oxygen vacancy concentration sandwiched by two STO thin films with low oxygen vacancy concentration. The microstructure and dielectric properties of the trilayer were then studied. X-ray diffraction analysis indicated that the trilayer was a relaxed STO multilayer formed by two STO thin layers with different lattice parameters. An improved optimization of high tunability and low loss was achieved in the relaxed trilayer. PACS 77.84.Bw; 68.55; 77.22.Ch; 68.35.Ct; 74.80.Dm     

Room temperature single-step electrosynthesized copper ferrite thin films and study of their magnetic properties

A single-step electrosynthesis of copper ferrite thin films from aqueous bath (which avoids anodization step for an incorporation of oxygen species into deposit) has been carried out at room temperature. Observed tetrahedral structured nanocrystalline copper ferrite thin films showed smooth, uniform and compact surface morphology. After annealing, increase in dielectric constant and reduced dielectric loss were observed. The saturation magnetization for annealed films was 292 emu/cm³ comparable to that of other reported ferrites.     

Room-temperature pulsed laser deposition and dielectric properties of amorphous Bi3.95Er0.05Ti3O12 thin films on conductive substrates

Bi_3.95Er_0.05Ti₃O₁₂ (BErT) thin films were prepared on Pt/Ti/SiO₂/Si and indium-tin-oxide (ITO)-coated glass substrates at room temperature by pulsed laser deposition. These thin films were amorphous with uniform thickness. Excellent dielectric characteristics have been confirmed. The amorphous BErT thin films deposited on the Pt/Ti/SiO₂/Si and ITO-coated glass substrates exhibited almost the same dielectric constant of 52 with a low dielectric loss of less than 0.02 at 1 kHz. Meanwhile, the dielectric properties of the thin films had an excellent bias voltage stability and thermal stability. The amorphous BErT thin films might have potential applications in microelectronic and optoelectronic devices.     

Effect of O2 gas partial pressure on structures and dielectric characteristics of rf sputtered ZrO2 thin films

Amorphous and polycrystalline zirconium oxide thin films have been deposited by reactive rf magnetron sputtering in a mixed argon/oxygen or pure oxygen atmosphere with no intentional heating of the substrate. The films were characterized by high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and capacitance versus voltage (C-V) measurements to investigate the variation of structure, surface morphology, thickness of SiO₂-like interfacial layer as well as dielectric characteristics with different oxygen partial pressures. The films deposited at low oxygen partial pressures (less than 15%) are amorphous and dense with a smooth surface. In contrast, the films prepared at an oxygen partial pressure higher than 73% are crystallized with the microstructure changing from the mixture of monoclinic and tetragonal phases to a single monoclinic structure. The film structural transition is believed to be consequences of decrease in the oxygen vacancy concentration in the film and of increase of the energetically neutral particles in the plasma due to an increased oxygen partial pressure. SE measurements showed that significant interfacial SiO₂ growth has taken place above approximately 51%. The best C-V results in terms of relative dielectric constant values are obtained for thin films prepared at an oxygen partial pressure of 15%.