钛酸锶钡铁电薄膜的制备与性能优化研究

综述了目前钛酸锶钡(BST)铁电薄膜最为常用的4种制备工艺:磁控溅射法(Magnetron Sputtering)、脉冲激光沉积法(PLD)、溶胶-凝胶法(Sol-gel)、金属有机物化学气相沉积法(MOCVD)。并介绍了在优化BST铁电薄膜性能方面所作的工作和取得的成果。     

硅基锆钛酸铅铁电薄膜异质结构的研究进展

介绍了锆钛酸铅铁电薄膜异质结构的研究进展,举例说明了锆钛酸铅薄膜异质结构的特性,并进行了分析比较。氧化物电极结构将替代现有的金属电极结构,从而有效解决铁电性能的退化问题,是未来铁电薄膜异质结构的发展方向。     

锂磷氧氮(LiPON)薄膜的制备及应用进展

介绍了锂磷氧氮(LiPON)薄膜的结构与特性,综述了LiPON薄膜的制备方法以及应用情况,并就LiPON薄膜制备中出现的困难和以后的研究方向做了简单的评述.     

VO2薄膜制备及掺杂研究进展

二氧化钒(VO2)是一种性能优异的功能材料,在68℃左右发生金属态-半导体态的转变,其光学和电学性能发生突变,在热电开关、光存储介质和激光防护方面有广泛的应用前景。但是由于钒氧体系十分复杂,给制备高质量的VO2带来了困难。人们做了许多工作来研究VO2的结构性能,使用不同的工艺方法制备VO2以及通过掺杂降低其相变温度。本文通过一些有代表性的VO2的研究成果,从制备工艺和元素掺杂方面做了介绍。     

钛酸锶陶瓷烧结的研究进展

钛酸锶陶瓷电容具有高储能、低损耗、高稳定性等优点,但烧结温度高,烧成密度低.依据国内外钛酸锶陶瓷烧结的研究情况,综述了影响钛酸锶陶瓷烧结中的两大因素,即烧结工艺和烧结助剂等方面的研究进展,并对其进行了展望.     

Bi4Ti3O12铁电薄膜的制备及研究进展

铁电薄膜具有良好的铁电、介电性能,在非挥发存储器件方面有很好的应用前景.本文介绍了钛酸铋(Bi4Ti3O12)铁电薄膜的研究现状,对目前Bi4Ti3O12铁电薄膜最常用的几种主要制备方法及其掺杂改性进行了评述,指出了Bi4Ti3O12铁电薄膜研究中亟待解决的几个问题.     

用溶胶—凝胶法制备薄膜电加热器

文章介绍了用溶胶—凝胶法制备薄膜电加热器的工艺原理和工艺过程。并介绍了各工艺参数对电热膜的性能影响。     

薄膜电加热器的制备（上）

介绍了采用绝缘釉和陶瓷基板的薄膜电加热器的研制情况及影响薄膜质量相关因素。     

Ferroelectric properties of Al and Nb doped PbTiO3 thin films prepared by chemical solution deposition process

Abstract

Thin films of pure and acceptor (Al) as well as donor (Nb) doped PbTiO₃ were prepared using a chemical solution deposition method. The nominal compositions of the solutions were equivalent to those of PbTiO₃, Pb(Ti_0.95Al_0.95)O₃ and Pb(Ti_0.95Nb_0.05)O₃, respectively. In the case of PbTiO₃, the remanent polarization amounted to 43 μC/cm², but the shape of the hysteresis curve was round. On the other hand, Al and Nb doped PbTiO₃ thin films exhibited well-saturated P-Ehysteresis curves. The shape of these curves was slim compared to that of PbTiO₃. The remanent polarization of the Pb(Ti_0.95Al_0.05)O₃ and Pb(Ti_0.95Al_0.05)O₃ thin films amounted to 18 and 15 μC/cm², respectively, and the coercive field decreased in comparison with that of PbTiO₃. The leakage currents of the PbTiO₃, Pb(Ti_0.95Al_0.05)O₃ and Pb(Ti_0.95Al_0.05)O₃ thin films were 7.68x10^?3, 3.21x10^?6 and 6.58x10^?4 A/cm², respectively, at+10V.     

Multilayer Ceramic Capacitors with Thin (Ba,Sr)TiO3 Layers by MOCVD

Barium strontium titanate ((Ba,Sr)TiO₃; BST) thin films were prepared on platinum-coated MgO substrates at 650°C by metalorganic chemical vapor deposition (MOCVD). Perovskite single phased BST thin films were obtained. Dielectric constant at 1 kHz–100 mV was 1000. Multilayer ceramic capacitor with twelve BST dielectric layers of 0.26 m thick was formed on the MgO substrate. Capacitance and dissipation factor (tan) at 1 kHz–100 mV were 32 nF and 1.5% respectively. Capacitance per unit volume of 33 F/mm³ provided 10 to 20 times larger volumetric efficiency than the conventional multilayer ceramic capacitors. Temperature coefficient of capacitance was –4000 ppm/°C. The leakage current at 1 V was 2.3×10^-9 A that yielded an acceptable CR product of 12.8 M-F. MOCVD was proposed as one of the promising manufacturing technologies for multilayer ceramic capacitors of high performance with sub-micron thick dielectric layers.     

Sintering Behaviour of BaxSr1-xTiO3

This paper deals with the sintering behaviour of Barium Strontium Titanate (BST). Two methods were examined; method 1: BaTiO₃ + SrTiO₃ source powders; method 2: BaCO₃ + SrCO₃ + TiO₂ source powders. Commercially available 50 nm BST (x = 0.60) powder was used to investigate the effect of particle size on activation energy (E_a). Discs were sintered in a Netzsch 402C Dilatometer and E_a for the powders were obtained by applying the Arrhenius expression. The results indicate powders made from both methods display a varying trend in E_a over a range of x. The commercial powder yielded a higher E_a compared with powder made from method 1.     

铁电薄膜漏电流研究现状

铁电薄膜的漏电流问题一直是困扰铁电存储器发展的重要问题。文章介绍了铁电薄膜的主要导电机理如热激发电子电导、空间电荷限制电流(SCLC)、Pool-Frenkel发射、肖特基发射等,影响漏电流大小的主要因素如薄膜厚度、工艺温度、晶粒尺寸、电极材料、搀杂离子等。同时介绍了漏电流对铁电薄膜极化和抗疲劳特性的影响。     

Epitaxial thin film heterostructures of relaxor ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3

Abstract

We have grown stoichiometric pure perovskite phase Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) thin films and PMN-PT/SrRuO₃ heterostructures on miscut (100) SrTiO₃ substrates by pulsed laser deposition. X-ray diffraction θ–2θ scans show that the PMN-PT films are purely c-axis oriented. The off-axis Φ scans show that the heterostructures grow “cube-on-cube” with an in-plane epitaxial arrangement of PMN-PT[100], [010] // SrRuO₃[001] // SrTiO₃[100] and PMN-PT[010], [100] // SrRuO₃[110] // SrTiO₃[010]. The crystalline quality of the films found to be comparable to that of bulk single crystals. The AFM images show that the SrRuO₃ and PMN-PT layers have smooth surfaces with root mean square roughness of 9Å. These epitaxial heterostructures can be used for the fabrication of piezoelectric devices.     

Microwave Dielectric Properties of Ferroelectric Pb(Zr1 − x Ti x )O3 Thin Films Using Interdigital Capacitors

Ferroelectric Pb(Zr_{1 ? x} Ti _x )O₃ (PZT) films were deposited on (001) MgO single crystals using sol-gel method. Structural properties and surface morphologies of PZT films were investigated using an X-ray diffractometer and a scanning electron microscopy, respectively. The dielectric properties of PZT films were investigated with the dc bias field of 0–135 kV/cm using interdigitated capacitors (IDC) which were fabricated on PZT films using a thick metal layer by photolithography and etching process. The small signal dielectric properties of PZT films were calculated by a modified conformal mapping method with low and high frequency data, such as capacitance measured by an impedance gain/phase analyzer at 100 kHz and reflection coefficient (S-parameter) measured by a HP 8510C vector network analyzer at 1–20 GHz. The IDC on PZT films exhibited about 67% of capacitance change with an electric field of 135 kV/cm at 10 GHz. These PZT thin films can be applied to tunable microwave devices such as phase shifters, tunable resonators and tunable filters.     

Microwave Properties of Mn Doped (Ba1 - x,Srx)TiO3Thin Films for Tunable Phase Shifter

Ferroelectric Mn doped Ba_0.5Sr_0.5TiO₃ (Mn-BST) films with/without BaTiO₃ (BT) buffer layer have been grown on (001) MgO substrates by a pulsed laser deposition to investigate electrical tunability at microwave frequencies. Structural properties and surface morphologies of the films were investigated using an X-ray diffractometer and a scanning electron microscope, respectively. Microwave dielectric properties of Mn-BST thin films with BT buffer were studied for reduction of dielectric loss and improvement of electrical tunability. Distributed analog phase shifters have been designed and fabricated on Mn-BST films with/without BT buffer layer to understand microwave dielectric properties. The differential phase shift of the phase shifter fabricated on Mn-BST film was 22° at 10 GHz with 80 V of applied dc bias voltage. In comparison, phase shifter fabricated on Mn-BST/BT multilayers exhibit 41° of differential phase shift at the same condition. This suggests that a BT buffer layer is for microwave tunable device applications. The phase shifter fabricated on Mn-BST/BT multilayers exhibit a low insertion loss (S₂₁) of ?1.1 dB, and a low return loss (S₁₁) of ?14 dB with a bias voltage of 80 V.