Microstructure and magnetic behavior of electrodeposited CoPt thick films upon annealing

CoPt films with a thickness about 5-μm consisting of a disordered face-centered cubic phase have been prepared by using the electrodeposition technique. X-ray diffraction measurements and transmission electron microscopy studies reveal that the annealed CoPt films possess a nanocomposite microstructure of A1 + L1₀ CoPt and the size and volume fraction of the L1₀ ordered phase increase with annealing time. A strong magnetic exchange coupling between the A1 phase and the L1₀ ordered phase is observed after annealing for 2.5 h, which yields a large coercivity H_c = 14.2 kOe and a high remanence ratio M_r/M_s = 0.88 for the nanocomposite thick films of A1 + L1₀ CoPt.     

A low-temperature pyroelectric study of PVDF thick films

Pyroelectric coefficient measurements were made at various temperatures for poled and unpoled samples of PVDF films. Samples were produced using the spin-coating technique onto glass substrates. Experiments were made using the quasi-static technique. PVDF samples were poled at various electric field strengths and the relation between poling field strength and the pyroelectric coefficient was investigated. The effect of the poling temperature was also studied. The maximum pyroelectric coefficient was obtained for a poling temperature of 340 K and for a poling field strength of . Dielectric permitivity and dielectric loss measurements were also performed in the 125–375 K temperature range.     

Influence of precursor solution coating parameters on structural and dielectric properties of PZT thick films

Ferroelectric PZT(70/30) thick films were fabricated by the hybrid technique adding the sol-coating process to the normal screen-printing process to obtain a good densification. The screen-printing procedure was repeated four times to form PZT(70/30) thick films, and then PZT(30/70) precursor solution was spin-coated on the PZT thick films. All PZT thick films showed the typical XRD patterns of a perovskite polycrystalline structure. The thickness of all thick films was approximately 75–80 μm. The relative dielectric constant and dielectric loss of the PZT-6 thick film were 656 and 1.2%, respectively. The remanent polarization increased and coercive field decreased with increasing the number of sol coatings and the values of the PZT-6 thick films were 28.3 μC/cm² and 13.1 kV/cm, respectively. Leakage current density of PZT-6 thick films was 2.4 × 10⁻⁹ A/cm² at 100 kV/cm.     

拉伸速率对PVDF薄膜介电压电性能的影响

通过单轴拉伸工艺制备了PVDF压电薄膜,运用X射线衍射和FTIR分析技术分析了不同拉伸速率下薄膜的微观结构;并探讨了极化电场对薄膜压电介电性能的影响.结果表明PVDF经单轴拉伸后,体系中出现了压电性能很强的β相和γ相,而且拉伸速率越高,体系出现的β相和γ相越多.随着极化电场的升高,PVDF压电薄膜的压电应变系数升高,介电常数升高,介电损耗降低.     

Conduction and dielectric polarization in Se thin films

Se films were prepared by thermal evaporation technique in thickness range 150-8500 Å. X-ray diffraction measurements showed that Se films are in the amorphous state. The ac conductivity and dielectric properties of the amorphous Se films have been investigated in the frequency range 100-100 KHz and 100-400 K temperature range. The ac conductivity σ_ac(ω) is found to be proportional to ω^s where s<1. The temperature dependence of both ac conductivity and the parameter s is reasonably well interpreted by the correlated barrier (CBH) model. The dc conductivity at the room temperature was also studied in the same thickness range. It was concluded that the same mechanism of carrier motion might be dominant in both ac polarization and dc conduction. This carrier transport mechanism might be electronic.     

Weak-link behavior in superconducting thick films

The surface impedance of melt-processed thick films of YBa₂Cu₃O_7–x on yttria-stabilized zirconia substrates has been measured as a function of temperature over the frequency range 9–18 GHz using an endwall replacement technique. The temperature dependence of both the penetration depth and the surface resistance of thisp-type cuprate system can be described within a two-gap weak-link model. The surface resistance scaled to 10 GHz by the observedf ² frequency dependence gives a value of 1.8 m at 77 K, which compares favorably with the lowest reported values for thick films of this material at microwave frequencies. Trends in material processing indicate that increasing the grain size would further decrease the surface resistance at microwave frequencies.     

Study of $$\upbeta $$-phase development in spin-coated PVDF thick films

A study was conducted to ascertain the effect of variation in spin speed and baking temperature on \(\upbeta \)-phase content in the spin-coated poly(vinylidene fluoride) (PVDF) thick films (\({\sim }4{-}25\,\upmu \hbox {m}\)). Development of \(\upbeta \)-phase is dependent on film stretching and crystallization temperature. Therefore, to study the development of \(\upbeta \)-phase in films, stretching is achieved by spinning and crystallization temperature is adjusted by means of baking. PVDF films are characterized using Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy. It is observed that crystallization temperature lower than \(60^{\circ }\hbox {C}\) and increase in spin speed increases the \(\upbeta \)-phase content in PVDF films. Crystallization temperature above \(60^{\circ }\hbox {C}\) reduces \(\upbeta \)-phase content and increases \(\upalpha \)-phase content. It was also observed that viscosity of the PVDF solution affects the \(\upbeta \)-phase development in films at a particular spin speed.     

Conduction and dielectric polarization in thin anodic aluminium oxide films

The a.c. polarization of anodic Al₂O₃ films was studied in the thickness range 30–1500 Å and the frequency range 300 Hz to 15 kHz. The interfacial polarization mechanism involving distinct regions separated by flaws and/or voids in the bulk was thought to become dominant with decreasing thickness because of an increasing concentration of defects. The d.c. conductivity at the room temperature was also studied in the same thickness range. The observed linear log J versus E^1/2 characteristics for several thicknesses showed that d.c. conduction in these films obeys the Poole-Frenkel law over a certain range of applied electric fields. Anomalies observed in the electric field and the thickness dependences of the d.c. conductivity are considered to arise from the thickness dependence of the defect concentration. It was concluded that the same mechanism of carrier motion might be dominant in both a.c. polarization and d.c. conduction.     

CO2 laser annealing of plasma-deposited high-T c superconducting thick films

Recent advances in the fabrication of high-T _c superconducting thick films demand processing techniques which can eliminate film/substrate interdifiusion that occurs during subsequent post-annealing heat treatment after the film is deposited, thereby limiting the application of the thick films for devices. The present study evaluates laser annealing techniques for plasma-deposited Y-Ba-Cu-O thick films using a high-energy CO₂ laser (10.6Μm) in a continuous wave mode. The results are compared with those obtained by conventional furnace annealing techniques necessary for post-heat treatment of as-deposited superconducting thick films. The high-T _c superconducting phase is recovered by cationic diffusion during subsequent post-annealing heat treatment. Crystallographic phases and microstructural characterization have been performed using XRD, SEM, and EPMA analytical techniques. The significance of the technology lies in the elimination of film/substrate interdiffusion problems, thereby resulting in high-quality superconducting thick films. The technology will significantly reduce the post-annealing times usually required by conventional furnace annealing techniques.     

Preparation and characterization of PI/PVDF composite films with excellent dielectric property

All-organic polyimide (PI)/poly(vinylidene fluoride) (PVDF) composite materials with high dielectric constant and low dielectric loss were fabricated via solution blending. The dielectric, mechanical, and thermal properties of the PI/PVDF composite films were studied. Results indicated that the dielectric properties of the composites were highly reinforced through the introduction of PVDF, and the composites exhibited excellent thermal stability. When the mass fraction of PVDF was adjusted to 30 wt%, the specimen demonstrated excellent thermal properties, superior mechanical properties, high dielectric constant (5.7, 1 kHz), and low dielectric loss (0.009, 1 kHz). Moreover, the dependence of the dielectric constant and dielectric loss on frequency was investigated. The composite presented stable dielectric constant and dielectric loss that were less than 0.04 within the testing frequency range of 100 Hz–10 MHz. This study demonstrated that the PI/PVDF composites were potential dielectric materials in the field of electronics.     

Influence of cobalt on annealing of zero magnetostrictive Ni-Fe-Co films

Zero magnetostrictive films about 1000 Å thick with cobalt contents from 0 to approximately 50 percent have been subjected to easy- and hard-axis saturating fields. The changes in characteristics were examined on aging for four hours in 30°C steps up to 240°C. Anisotropy field, dispersion, and coercive force were examined. The anisotropy and dispersion changes on aging indicated somewhat faster aging for samples with increasing cobalt. This is as expected for anM-induced annealing mechanism. However, the differences were small; maximum differences in the parameters, after aging to 150°C, between samples with different cobalt contents were ±10 percent.     

有机载体对钡铁氧体厚膜微结构的影响研究

本文采用丝网印刷方法来制备钡铁氧体厚膜,研究了钡铁氧体浆料的成分对钡铁氧体厚膜表面形貌的影响,并讨论了排胶时间对其表面形貌的影响.研究结果表明,采用松油醇和柠檬酸三丁酯构成的混合溶剂可以有效改善钡铁氧体浆料的挥发特性,进而降低钡铁氧体厚膜的气孔率,提高厚膜的饱和磁化强度.通过降低有机载体的比例,可以提高钡铁氧体厚膜的致...     

PVDF压电薄膜的应变传感特性研究

PVDF压电薄膜是一种重要的智能材料。本文理论分析了智能材料——PVDF压电薄膜的应变传感机理；研究了PVDF应变传感器的制作与布设工艺；试验研究了PVDF传感元件在准静态和动态响应下的传感特性．得到了PVDF传感元件的电压灵敏度，并分析了PVDF压电薄膜的尺寸对灵敏度的影响。研究结果表明：PVDF传感器具有灵敏度高、线性度好、制作与布置工艺简单、面监测等优点．适用于土木工程结构的健康监测。     

Influence of thickness on nanomechanical behavior of Black Diamond™ low dielectric thin films for interconnect and packaging applications

In the present study, we have investigated the thickness dependence of mechanical properties of the Black Diamond? (SiOC:H, BD, Low-k) films, which are of great interest in current Cu/low-k Back End of the Line (BEOL) interconnect/packaging technologies. For this investigation the BD thin films of six different thicknesses 100, 300, 500, 700, 1,000 and 1,200 nm were deposited on the 8″ Si wafer by using plasma enhanced chemical vapor deposition (PECVD) technique. Nanoindentation and nanoscratch tests of the BD films were performed by using the Nano Indenter^® XP (MTS Corp. USA). In nanoindentation testing of the BD films, significant differences in the elastic modulus of the BD films were observed. In nanoscratch testing, it is found that the critical load (Lc) and scratch width increases as the thickness of the film increases. Cross-sectional analysis of residual nanoindentation impressions was carried out using atomic force microscopy (AFM) to study the deformation behavior. The nanoindentation and nanoscratch responses of the BD thin films of six different thicknesses are different and they are expected mainly due to the molecular reorganization in thin/ultra thin films.     

The annealing behavior of Ge-Au-Ni,Ge-Au-Pt and Ge-Au-Pd trilayered films

Interdiffusion in Au-Ge-Ni, Au-Ge-Pt and Au-Ge-Pd trilayered electro- gun-evaporated thin films on SiO₂ substrates was investigated by backscattering, scanning electron microscopy and X-ray diffraction. We observed that, when the amount of germanium is less than 100 at.% of that of nickel, palladium or platinum in the trilayered films, heat treatment yields laterally uniform two-layered films consisting of a germanide layer and a gold layer. When more germanium is present than is required to complete the formation of the most germanium-rich germanide (GeNi, GePd, Ge₂Pt), the films are laterally non-uniform after annealing above or below the Au-Ge eutectic temperature (356°C). The behavior of Au-Ge-Ni on SiO₂ is compared with that obeseerved on GaAs as substrate.     

Influence of annealing on the optical properties of amorphous germanium films

The influence of annealing on the optical, electrical and structural properties of thin amorphous Ge films deposited under well-defined conditions has been investigated. The results below the onset of recrystallization are interpreted as due to a progressive elimination of defects and an evolution of the films towards an “ideal” amorphous state. Various mechanisms are discussed in relation with various structural models.     

Influence of magnetic annealing on high-frequency magnetic properties of FeCoNd films

FeCoNd thin film with thickness of 166 nm has been fabricated on silicon (1 1 1) substrates by magnetron co-sputtering and annealed for one hour under magnetic field at different temperatures (T_a) from 200 °C to 700 °C. The As-deposited and annealed FeCoNd film samples at T_a ≤ 500 °C were amorphous while the ones obtained at T_a ≥ 600 °C were crystallized. We found that the perpendicular anisotropy field gradually decreases as the annealing temperature increases from room temperature to 300 °C. A well induced in-plane uniaxial anisotropy is achieved at the annealing temperature between 400 and 600 °C. The variation of the dynamic magnetic properties of annealed FeCoNd films can be well explained by the Landau-Lifshitz equation with the variation of the anisotropy field re-distribution and the damping constant upon magnetic annealing. The magnetic annealing might be a powerful post treatment method for high frequency application of magnetic thin films.     

Microwave dielectric behavior of nanocrystalline titanium dioxide thin films

Dielectric behavior of titania thin films, deposited by DC magnetron sputtering on to borosilicate glass substrates, in the microwave region is reported. Deposition in a 100% pure oxygen DC plasma is demonstrated. The nanocrystalline films showed a crystallite size range between 16 and 50 nm. The crystallite size decreased with increase in film thickness between 150 and 700 nm and increase in rate of deposition. Refractive index decreased with increase in percentage of oxygen in the sputter gas. The dielectric constants were measured using the extended cavity perturbation technique at 8.98, 10.01 and 10.98 GHz. The dielectric constant and loss tangent showed a very small decrease with increase in frequency but exhibited a stronger dependence on processing parameters as well as crystallite size. The dielectric constant peaked at a value of 46 (±0.1) at a frequency of 8.98 GHz with 50% O₂ in the plasma, decreasing above and below it. Similarly, it peaked at a value of 46 (±0.1) for a crystallite size of 40 nm decreasing thereafter. Interestingly, the dielectric constant also showed a maximum at a bandgap of 3.36 eV at the same value. In each case the maximum dielectric constant was accompanied by a minimum in the dielectric loss. The variation in the dielectric properties can be correlated with microstructural changes as evidenced by SEM and AFM images.     

N含量对CNx薄膜结构和介电性能的影响

利用双放电腔微波ECR等离子体增强非平衡磁控溅射(MW-ECR PEUMS)系统,在室温下制备CNx薄膜.通过傅立叶变换红外光谱、X光电子能谱表征技术以及椭偏仪测试手段,研究了N含量对CNx薄膜结构和介电性能的影响.研究结果表明,随着CNx薄膜N/C比的增大,sp3 C-N的形成受到抑制,sp2 C-N的形成增多,薄膜折射率以及介电常数电子极化贡献部分降低.     

Influence of vacuum annealing on the properties of SILAR CuInS2 thin films and optimization of annealing duration

The structural, compositional, morphological and optical properties of as-deposited and vacuum annealed CuInS₂ thin films prepared by successive ionic layer adsorption and reaction method are studied by X-ray diffractometer, energy dispersive X-ray analyzer, scanning electron microscope and spectrophotometer respectively. The influence of vacuum annealing on the properties of CuInS₂ (CIS) thin films is discussed, annealing duration has also been optimized and reported in this paper.