Electrodeposited hydroxyapatite coatings in static magnetic field

Uniform hydroxyapatite (HA) coatings were deposited electrochemically on titanium in magnetic fields. The structure and morphology of the deposited films were investigated by scanning electron microscopy, X-ray diffraction and transmission electron microscopy (SEM, XRD and TEM). It was found that the morphology of HA deposits could be altered by direction and intensity of applied magnetic field. Needle-like crystals formed when magnetic field was applied perpendicularly to electric field (B⊥ J), whereas spherical nanocrystals formed when magnetic and electric fields were in parallel (B||J). In addition, the nucleation rate of the HA crystals was proportional to the magnetic field intensity. Therefore, the resultant crystal size decreased with increasing magnetic field intensity.     

Characterization and tunneling conductance spectra of N,N′-bis (9H-fluoren-9-ylidene)benzene-1,4-diamine thin films on graphite

N,N′-bis(9H-fluoren-9-ylidene)benzene-1,4-diamine was synthesized via the acetic acid-assisted Schiff base reaction between 9-fluorenone and p-phenylenediamine. The thin films were deposited from solution and characterized by contact angle measurements (CAM), X-ray photoelectron spectroscopy (XPS) and tunneling conductance spectroscopy (TCS). The tunneling conductance spectra, related to the potential and distance between the tip and substrate, were acquired at different tip–substrate separations and depicted significant trend under the action of electric field. Systematic analysis shows more information about electron transport through medium layers. The electric field plays an important role in tunneling conductance spectra. The tunneling conductance spectra data indicate the electric field dependence of electron transport.     

不锈钢衬底两面同时液相电沉积类金刚石薄膜及其沉积机理研究

为了利用液相电沉积技术实现在金属衬底表面全方位电沉积类金刚石(DLC)薄膜,采用不同尺度的不锈钢片作为衬底,在表面电沉积了DLC薄膜,利用X射线光电子能谱、Raman光谱和扫描电子显微镜分别对衬底两面薄膜的化学成分、微观结构和表面形貌进行了分析。结果显示:对于尺度大于石墨阳极的不锈钢衬底,仅在衬底正对着阳极的一面实现了DLC薄膜的沉积;而对于尺度小于阳极的不锈钢衬底,在衬底两面都有DLC薄膜沉积,且两面薄膜结构相似,形貌相近。利用准静态电场理论对实验结果进行了解释,提出在金属衬底表面实现液相电沉积DLC薄膜的前提条件是存在垂直于衬底表面的电场分量,为进一步实现在复杂形状的导电性衬底表面沉积DLC薄膜提供了理论依据。     

Structure, electrical conductivity and Hall Effect of amorphous Al-C-N thin films

A series of Al-C-N thin films with different Al contents were deposited on Si (100) substrates by closed field unbalanced reactive magnetron sputtering in the mixture of argon and nitrogen gases. Their phase configurations and structures were subsequently investigated by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy measurement, cross-sectional field emission scanning electron microscopy and high-resolution transmission electron microscopy, while their electrical conductivities and Hall Effects were studied by physical property measurement system. The results indicated that all deposited Al-C-N thin films were amorphous. There were three bonds, C-N, C-C and Al-N, in Al-C-N thin films irrespective of Al content. Increase of Al content increased the amount of Al-N bonding at the cost of that of C-C bonding. Higher Al content led to less sp² C-C bonding. The films with low Al content were essentially P-type semiconductor. Increase of Al content increased the electrical resistance, making the film gradually transform to insulation, which was attributed to increase of band gap. Hall coefficient was increased with increase of Al content, which was contributed to decrease in concentration and mobility of hole in the films.     

CVD金刚石膜的场发射机制

利用热灯丝化学气相沉积方法在光滑的钼上沉积了金刚石膜,用扫描电子显微镜和Raman谱对金刚石膜进行了分析。结果表明金刚石膜是由许多金刚石晶粒组成,晶粒间界主要是石墨相,并且在膜内有许多缺陷。金刚石膜的场发射结果表明高浓度CH4形成的金刚石膜场发射阈位电场较低浓度CH4形成的金刚石为低。这意味着杂质（如石墨）和缺陷（悬挂键）极大地影响了膜的场发射性能。根据以上结果,提出了一种CVD金刚石膜的场发射机制即膜内的缺陷增强膜内的电场,石墨增大电子的隧穿系数以增强CVD金刚石膜的场发射。     

直流负偏压对类金刚石薄膜结构和性能的影响

利用直流-射频-等离子体增强化学气相沉积技术在单晶硅表面制备了类金刚石薄膜，采用原子力显微镜、Raman光谱、X射线光电子能谱、红外光谱、表面轮廓仪和纳米压痕仪考察了直流负偏压对类金刚石薄膜表面形貌、微观结构、沉积速率和硬度等性能的影响。结果表明：无直流负偏压条件下，薄膜呈现有机类聚合结构，具有较低的SP3含量和硬度；叠加上直流负偏压后，薄膜具有典型的类金刚石结构特征，SP3含量和硬度得到了显著的提高；但随着直流负偏压的升高，薄膜的沉积速率和H含量逐渐降低，而SP3含量和硬度在直流负偏压为200V时出现最大值，此后逐渐降低。     

Properties of amorphous silicon thin films synthesized by reactive particle beam assisted chemical vapor deposition

Amorphous silicon thin films were formed by chemical vapor deposition of reactive particle beam assisted inductively coupled plasma type with various reflector bias voltages. During the deposition, the substrate was heated at 150 °C. The effects of reflector bias voltage on the physical and chemical properties of the films were systematically studied. X-ray diffraction and Raman spectroscopy results showed that the deposited films were amorphous and the films under higher reflector voltage had higher internal energy to be easily crystallized. The chemical state of amorphous silicon films was revealed as metallic bonding of Si atoms by using X-ray photoelectron spectroscopy. An increase in reflector voltage induced an increase of surface morphology of films and optical bandgap and a decrease of photoconductivity.     

Study of electrical polarization hysteresis in ferroelectric polyvinylidene fluoride films

Electric properties of polyvinylidene (PVDF) films fabricated using the Langmuir-Schaefer method have been studied. Films of different thickness were deposited on silicon substrates and analyzed using several techniques. X-ray diffraction (XRD) data showed that PVDF films crystallize at an annealing temperature above 130 °C. Polarization versus electric field (PE) ferroelectric measurements was done for samples prepared with electrodes. PE measurements show that the coercivity of the films increases as the maximum applied electric field increases. The coercivity dependence on the frequency of the applied electric field can be fitted as f^0.6. The results also show that the coercivity decreases with increasing the thickness of PVDF film due to the pinning effect.     

DEPOSITION OF DIAMOND-LIKE AND OTHER SPECIAL COATINGS BY PULSED LASER ABLATION AND THEIR POST-SYNTHESIS PROCESSING

Use of pulsed laser ablation technique for deposition of diamond-like and other special coatings is discussed here at length, establishing the correlation between the process parameters and the film quality. Process parameters dealt with sufficient detail are the laser wavelength, laser pulse width and energy density, nature of ambient and the corresponding partial pressure, substrate temperature and the electric field, if any, applied during deposition. The optimum parameter space for deposition of films having high performance features are identified in the case of diamond-like films and films of cubic boron nitride, titanium nitride and tungsten carbide. In this context, results on the characterization of the films deposited under different conditions are discussed. These include data obtained by Raman spectroscopy, IR spectroscopy, X-ray diffraction, ellipsometry, UV-VIS transmission, scanning electron microscopy. The post-synthesis of the laser deposited films using ion and laser beams from I he standpoint of enhancing their quality or etching of dielectric features therein are also discussed.     

The effect of parallel electric fields on the orientation of polycrystalline zinc oxide thin films produced by reactive evaporation and oxidation of zinc

The effect of an electric field (detached electrodes) on the crystal orientation of zinc oxide thin film was investigated. Two methods, direct and indirect, were utilized to produce zinc oxide thin films. In the direct method (reactive evaporation) oxygen was introduced into the zinc vapour stream and ZnO films were deposited on cold substrates in a vacuum system. Parallel electric fields were applied during the reaction process. It was observed that the electric field had no effect on the preferred c-axis orientation of the ZnO crystals. There was no significant difference in the crystal size or surface texture of ZnO samples subjected to electric fields with respect to the sample that experienced no electric field. In the indirect method (oxidation) electric fields were applied during the evaporation of zinc then the samples were oxidized in air in a furnace at 600 C. Here the application of electric field improved the c-axis orientations. The crystal size remained unchanged, but the surface morphology was affected by the application of the electric field. Whenever the c-axis orientation improved, crystals on the surface became rounded and a more ordered microstructure was observed.     

Influence of RF power on structural,morphology, electrical,composition and optical properties of Al-doped ZnO films deposited by RF magnetron sputtering

In this study, influence of RF power on the structural, morphology, electrical, composition and optical properties of Al-doped ZnO (ZnO:Al) films deposited by RF magnetron sputtering have been investigated. Films were systematically and carefully investigated by using variety of characterization techniques such as low angle X-ray diffraction, UV–visible spectroscopy, Raman spectroscopy, Hall measurement, X-ray photoelectron spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy etc. Low angle X-ray diffraction analysis showed that the films are polycrystalline with hexagonal wurtzite structure and which was further confirmed by Raman spectroscopy analysis. Its preferred orientation shifts from (102) to (002) with increase in RF power. The average grain size was found in the range of 15–21 nm over the entire range of RF power studied. The FE-SEM analysis showed that grain size and surface roughness of ZnO:Al films increase in with increase in RF power. The UV–visible spectroscopy analysis revealed that all films exhibit transmittance >85 % in the visible region. The optical band gap increases from 3.37 to 3.85 eV when RF power increased from 75 to 225 W. Hall measurements showed that the minimum resistivity has been achieved for the film deposited at 200 W. The improvement in the electrical properties may attribute to increase in the carrier concentration and Hall mobility. Based on the experimental results, the RF power of 200 W appears to be an optimum sputtering power for the growth of ZnO:Al films. At this optimum sputtering power ZnO:Al films having minimum resistivity (8.61 × 10^?4 Ω-cm), highly optically transparent (~87 %) were obtained at low substrate temperature (60 °C) at moderately high deposition rate (22.5 nm/min). These films can be suitable for the application in the flexible electronic devices such as TCO layer on LEDs, solar cells, TFT-LCDs and touch panels.     

Characterization of iridium oxide thin films deposited by pulsed-direct-current reactive sputtering

Thin films of iridium oxide were deposited on silicon and borosilicate glass substrates by pulsed-direct-current (pulsed-DC) reactive sputtering of iridium metal in an oxygen-containing atmosphere. Optimum deposition conditions were identified in terms of plasma pulsing conditions, oxygen partial pressures, and substrate temperature. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and Rutherford backscattering spectroscopy. According to the results, it was possible to obtain films that are near-stoichiometric, smooth and uniform in texture. The films deposited without substrate heating were amorphous, and those deposited at substrate temperatures above 300 °C were found to have a homogeneous polycrystalline structure. The results also showed that pulsed-DC sputtered iridium oxide films were smoother and had lower micro-inclusions density than DC-sputtered films obtained under otherwise similar deposition conditions. This improvement in the film quality is at the expense of a tolerable decrease in the deposition rate.     

SiO2层上沉积的纳米多晶硅薄膜及其特性

采用低压化学气相沉积(LPCVD)系统以高纯SiH4为气源,在p型10.16 cm<100>晶向单晶硅衬底SiO2层上制备纳米多晶硅薄膜,薄膜沉积温度为620℃,沉积薄膜厚度分别为30 nm、63 nm和98 nm.对不同薄膜厚度的纳米多晶硅薄膜分别在700℃、800℃和900℃下进行高温真空退火.通过X射线衍射(XRD)、Raman光谱、扫描电子显微镜(SEM)和原子力显微镜(AFM)对SiO2层上沉积的纳米多晶硅薄膜进行特性测试和表征,随着薄膜厚度的增加,沉积态薄膜结晶显著增强,择优取向为<111>晶向.通过HP4145B型半导体参数分析仪对沉积态掺硼纳米多晶硅薄膜电阻I-V特性测试发现,随着薄膜厚度的增加,薄膜电阻率减小,载流子迁移率增大.     

Microstructure and magnetic properties of zinc ferrite thin films produced by pulsed laser deposition

Zinc ferrite thin films were deposited from a target of zinc ferrite onto a MgO substrate using XeCl excimer laser operating at 308 nm and frequency of 30 Hz. The crystallographic characterizations of the films were performed using X-ray diffraction (XRD). Microstructure, surface morphology, chemical composition and grain size, as well as surface roughness were obtained from scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The magnetic properties of the thin films were studied in the temperature range 5–300 K and in fields of up to 5 T using SQUID magnetometry. Data on temperature and field dependence of magnetization provide a strong evidence for superparamagnetism. Paper presented at 8 AGM of MRSI, BARC, Mumbai, 1997.     

Physical properties of very thin SnS films deposited by thermal evaporation

SnS films with thicknesses of 20-65 nm have been deposited on glass substrates by thermal evaporation. The physical properties of the films were investigated using X-ray diffraction (XRD), scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and ultraviolet-visible-near infrared spectroscopy at room temperature. The results from XRD, XPS and Raman spectroscopy analyses indicate that the deposited films mainly exhibit SnS phase, but they may contain a tiny amount of Sn₂S₃. The deposited SnS films are pinhole free, smooth and strongly adherent to the surfaces of the substrates. The color of the SnS films changes from pale yellow to brown with the increase of the film thickness from 20 nm to 65 nm. The very smooth surfaces of the thin films result in their high reflectance. The direct bandgap of the films is between 2.15 eV and 2.28 eV which is much larger than 1.3 eV of bulk SnS, this is deserving to be investigated further.     

The influence of the substrate and the substrate temperature on the crystallinity of tin films

Thin films of tin were prepared on various substrates (NaCl, KCl, KBr and KI) and at various substrate temperatures (28–90°C) and were studied using transmission electron microscopy and selected area electron diffraction techniques. To determine the dependence on cleanness, tin was deposited on single-crystal surfaces prepared by vacuum cleaving. Films were prepared on substrate surfaces to which a parallel d.c. electric field (0–1000 V cm⁻¹) was applied. It was observed that the crystallites of tin films deposited on KBr were more preferentially oriented than those deposited on NaCl, KCl or KI. The effects of vacuum cleaving and of d.c. electric fields are discussed.     

Multiferroic BiFeO3 thin films for multifunctional devices

We report the metalorganic chemical vapor deposition of crystalline BiFeO3 films on platinized silicon substrates using n-butylferrocene, triphenylbismuth and oxygen. Based on thermogravimetric analysis data, the suitability of these two precursors for depositing BiFeO3 is discussed. The deposited films were characterized for structure and morphology using X-ray diffraction and scanning electron microscopy. Composition analysis using X-ray photoelectron spectroscopy revealed that the films were stoichiometric BiFeO3. Electrostatic force microscopy indicated that the film had polarizable domains that showed no deterioration in polarization over time long after electric poling. The film showed a saturation magnetization of 10 +/- 1 emu/cm3 at room temperature.     

The electrical conductivity of copper and tin thin films vacuum deposited in a lateral electric field

Copper and tin thin films of different thicknesses in the coalescence thickness range (160, 210 and 260 Å) were grown by vacuum deposition onto clean glass substrates at room temperature under a pressure of 2 × 10^?5 Torr in different electric fields between 0 and 200 V cm^-1 aligned parallel to the substrates. The electrical conductivities of the films were measured immediately after formation both in situ and after letting air into the system.We found that the application of an electric field of less than 60 V cm^-1 decreased the resistance of the films. However, the application of stronger electric fields produced an increase in the film resistance. This is attributed to a disturbance of the electrostatic forces between the growing islands by the redistribution of charges in the presence of the applied electric field which causes an increased rate of coalescence of the islands in the film.     

Growth and characterization of diamond films deposited at high-pressure using a low-power microwave plasma reactor

Diamond films were deposited on molybdenum substrates from mixtures of methane diluted in hydrogen using a high-pressure microwave plasma reactor. In this reactor, a compressed waveguide structure was used to increase the electric field strength, and accordingly the reactor was able to operate stably with low gas flow rate and microwave power. The films deposited on 12 mm diameter substrates were characterized by film morphology, Raman spectra, growth rate and crystalline quality. The morphology of diamond films deposited in this reactor depends mainly on the substrate temperature. When the deposition pressure was 48 kPa and microwave power was only 800 W, high quality diamond films could be uniformly deposited with a growth rate around 20 μm/h.     

Temperature variation in the thermoelectric power of polycrystalline CdS films

The variation with temperature in the thermoelectric power of vacuum- deposited CdS films grown under the influence of a longitudinal d.c. electric field was investigated. The electric field strength was ±70, ±140 or ±210 V cm⁻¹, and the films were deposited onto glass substrates. The temperature variation in the resistance of the film is also reported and the field variation in the activation energy is discussed.