The effect of seed layer on morphology of ZnO nanorod arrays grown by hydrothermal method

Well-aligned ZnO nanorod arrays were synthesized by hydrothermal method on Si substrates that were covered with pre-deposited ZnO films as seed layers. The ZnO seed layers were deposited by RF magnetron sputtering. It is found that the seed layers prepared under different oxygen partial pressure sputtering parameters and annealing treatment have a great influence on the morphology of the ZnO nanorod arrays grown subsequently on them. Furthermore, growth positions of nanorod/microrod arrays were selectively controlled on the lithography-assist ZnO seed layer.     

织构金属衬底上CSD-SrTiO3薄膜的制备

涂层导体是发展77 K液氮温区强磁场下电力应用的实用化关键材料。由于缓冲层层数增加会导致控制生长、微观组织和界面结构的难度增大,所以简化缓冲层结构对涂层导体制备工艺的简化和成本的降低非常重要。本研究探索了低成本的化学溶液沉积(CSD)技术制备SrTiO_3(STO)缓冲层过程中前驱液热分解行为以及薄膜制备工艺路线对薄膜外延生长的影响,通过选取恰当的前驱液以及引入籽晶层沉积的方法最终获得了具有良好c轴织构且表面光滑的STO薄膜。     

Effect of anodising electrolyte on performance of AZ31 and AM60 magnesium alloys microarc anodic oxides

Abstract

Various oxide film layers were grown onto AZ31 and AM60 magnesium alloy substrates by micro-arc anodic oxidation (MAO) in alkaline phosphate solutions with different additives such as silicate, aluminate and tetraborate. Surface morphologies and phase composition of the films were assessed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The adhesion strength of the anodic oxides was evaluated by scratch testing. The electrolyte composition affects the surface morphology and the adhesion of the oxides to the alloy substrates. The anodising solution consisting of phosphate, tetraborate and silicate produces a better oxides adhesion compared to those achieved in other electrolytic solutions.     

Coating of hydroxyapatite films on metal substrates by seeded hydrothermal deposition

Hydroxyapatite (HAP) was successfully coated on various metal substrates by a novel seeded hydrothermal deposition method. A nanoscale HAP seed layer was first formed by a short electrochemical synthesis. The seed layer promotes HAP crystal growth onto the surface during a subsequent hydrothermal crystallization step. The surface morphology and microstructure of the HAP coatings can be regulated by varying the reaction temperature, solution pH, calcium-to-phosphorus molar ratio in the starting solution, and hydrothermal deposition time. The new method has advantages over many other reported HAP deposition techniques in that it produces highly crystalline, crack-free, adherent films of uniform thickness. In all the films, the HAP crystals are preferentially oriented with the c-axis normal to the substrate. The as-developed HAP coatings are attractive for applications in the area of bioactive surface modification of metallic implants where the microstructure of the film is advantageous for promoting bone growth.     

Growth of highly oriented Pt(100) thin films on a MgO(100) seed layer deposited on Si(100) substrates by rf magnetron sputtering

The growth of highly oriented Pt(100) thin films on Si(100) substrates deposited by rf magnetron sputtering was studied using a MgO(100) seed layer. The effects of the sputtering parameters on the growth of the MgO(100) seed layer were investigated in order to obtain the deposition condition which gives the best crystalline quality of (100) oriented MgO thin films. A highly crystallized MgO(100) film was obtained at a substrate temperature of 425°C, a rf power of 4.4W/cm² and a pressure of 12.5 mTorr. The crystalline quality of the MgO film was greatly decreased when the Si substrate was oxidized. The degree of (100) preferred orientation of the Pt film deposited on a MgO(100)//Si(100) substrate was found to be sensitive to the thickness of the MgO(100) seed layer, which is explained by the thickness dependence of the crystalline quality and the surface roughness of the MgO seed layer. A highly oriented Pt(100) film, for which the I₂₀₀/(_I200+I₁₁₁) ratio was about 0.8, was obtained at 550°C on a 50 nm thick MgO seed layer.     

常压干燥法制备过程中衬底类型对二氧化硅气凝胶薄膜形貌的影响

采用常压干燥法,在Ti、SiO₂、GaN、Al和Si 5种衬底上制备二氧化硅气凝胶薄膜,研究衬底类型对二氧化硅气凝胶薄膜形貌的影响。通过XPS法检测二氧化硅气凝胶薄膜与衬底之间的界面结合。采用椭偏仪结合反射光谱拟合的方法对二氧化硅气凝胶薄膜的折射率进行测量。通过原子力显微镜和场发射扫描电镜对二氧化硅气凝胶薄膜的表面及截面形貌进行观测。结果表明,二氧化硅气凝胶薄膜的形成会导致Al衬底表面Al-O中心峰产生0.07 eV的偏离,以及Ti衬底表面Ti 2p_3/2中心峰0.43 eV的偏离。这表明Al衬底和Ti衬底与二氧化硅气凝胶薄膜之间形成了某种化学键。同时,折射指数测量显示,Ti衬底表面形成的二氧化硅气凝胶薄膜折射指数最低(1.17),平均孔隙率(63.8%)比硅衬底表面形成的二氧化硅气凝胶薄膜孔隙率(57.2%)要高。衬底类型对二氧化硅气凝胶薄膜形貌的影响与不同衬底的亲水性有关。由于Ti衬底亲水性最佳,更多的颗粒在Ti衬底表面形核和长大,导致其上制备的二氧化硅气凝胶薄膜具有更大的表面粗糙度,以及更大的颗粒和孔径。     

不同厚度Tl-2212薄膜的表面形貌及超导特性研究

采用直流磁控溅射法和后退火技术在蓝宝石基片上制备了Tl-2212超导薄膜,考察了Tl-2212薄膜的厚度对其形貌和超导特性的影响。实验结果表明,随着超导薄膜厚度增加,其表面形貌由致密平整的结构演化为片状晶体结构,临界转变温度Tc和临界电流密度Jc先增大后减小,微波表面电阻Rs先减小后增大。在退火的CeO2缓冲层上所制备的无裂纹薄膜的最大厚度达到600nm,并仍然具有良好的超导性能。     

High photocatalytic activity of Cu_2O/TiO_2/Pt composite films prepared by magnetron sputtering

Cu_2O/TiO_2/Pt three-layer films were deposited on glass substrates using magnetron sputtering method.The surface morphology and the optical properties of the composite film were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), ultravioletvisible spectroscopy(UV-Vis) and photoluminescence spectroscopy(PL). The photocatalytic activity of the samples was evaluated by the photocatalytic degradation of methyl orange(MO) aqueous solution under visible light irradiation. The results indicate that the Cu_2O/TiO_2/Pt composite films are made up of three layers which are Pt layer,anatase-TiO_2 layer and Cu_2O layer from bottom to top. The surface of the films is even and composed of regular-shaped spherical particles. The photocatalytic activity of the Cu_2O/TiO_2/Pt three-layer film is much higher than that of the Cu_2O/TiO_2 double-layer film. Such enhancement is ascribed to the presence of Pt layer, which further inhibits the photogenerated electron-hole recombination, prolongs the lifetime of the photogenerated carriers, increases the quantum efficiency and hence improves the photocatalytic activity of the film effectively.     

纳米结构Ni-TiN复合薄膜的电沉积及腐蚀行为

采用电沉积方法在黄铜基底上制备纳米结构的Ni-TiN复合薄膜。用扫描电镜（SEM）及透射电镜（TEM）对其微观结构进行表征,利用X射线衍射（XRD）分析其平均晶粒尺寸,采用极化曲线及电化学阻抗谱（EIS）研究其腐蚀行为。结果表明,电沉积的电流密度、TiN纳米粒子的浓度、搅拌速度、溶液温度及pH值对电沉积薄膜形貌的影响较大。制备的Ni-TiNi电沉积薄膜的平均晶粒尺寸约为50nm。纳米结构的Ni-TiNi电沉积薄膜的耐腐蚀性能远优于纯Ni沉积薄膜的。     

LY12铝合金/钝化膜/环氧涂层复合电极的腐蚀电化学行为

通过电化学阻抗谱（EIS）技术研究了LY12铝合金／钝化膜／环氧涂层复合电极在NaCl水溶液中的腐蚀行为．结果表明，随浸泡时间的延长，复合电极体系的阻抗不断增大；在浸泡初期，复合电极体系的阻抗谱中即出现了低频扩散阻抗，认为该阻抗由金属表面钝化膜的溶解产物的传质引起．扫描电镜（SEM）观察表明铬酸盐钝化膜呈现明显的裂纹形貌；利于溶解的铬盐通过裂纹到达合金基体使其钝化，是复合电极阻抗不断增大的原因所在．     

Interficial stability of Cu/Cu(Ru)/Si contact system for barrier-free copper metallization

Films of Cu/Cu(Ru) and Cu(Ru) were deposited on Si substrates by magnetron sputtering. Samples were subsequently annealed and analyzed by four-point probe (FPP) measurement, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Auger electron spectroscopy (AES). After annealing at 500 °C, resistivity values of both systems decrease, but the reduction is more significant for Cu(Ru). Moreover, the resistivity values of annealed Cu(Ru) film are still greater than those of annealed Cu/Cu(Ru) film. XRD data suggest that Cu/Cu(Ru) film has higher thermal stability and Cu silicide cannot be observed up to 500 °C. According to TEM results, after annealing at 500 °C, the grain size of the Cu(Ru) film is smaller than that of Cu/Cu(Ru) film. In conjunction with AES, XRD, TEM analyses and sheet resistance measurement, it indicates that Cu/Cu(Ru) seed layers are potentially good for advanced Cu interconnects from the views of interfacial stability and low resistivity.     

In situ STM study of the duplex passive films formed on Cu(1 1 1) and Cu(0 0 1) in 0.1 M NaOH

In situ electrochemical scanning tunneling microscopy (ECSTM) investigations of the anodic Cu(I)/Cu(II) duplex passive layers grown on Cu(1 1 1) and Cu(0 0 1) in 0.1 M NaOH are reported. The outer Cu(II) part of the duplex film formed on both substrates is crystalline with a terrace and step topography. The observed lattices are consistent with a bulk-like terminated CuO(0 0 1) surface on both substrates. This common crystallographic orientation is explained by the hydroxylation of the otherwise polar and unstable oxide surface at the passive film/electrolyte interface. The epitaxy of the oxide layers is governed by the parallel alignment of the close packed directions of the CuO outer layers and Cu₂O inner layers on both substrates. A granular and amorphous layer covering the crystalline CuO(0 0 1) oxide has been observed on Cu(0 0 1) but not on Cu(1 1 1). It is assigned to a film of copper hydroxide corrosion products formed by a dissolution-precipitation mechanism. Its absence on the passivated Cu(1 1 1) surface is explained by the higher stability of the Cu₂O(1 1 1) precursor oxide formed on this substrate in the initial stages of growth of the duplex passive film, resulting in a lower amount of dissolved copper.     

Electrical properties of a-axis aligned lanthanum-modified lead titanate thin films prepared using sol-gel process

The (100) epitaxial lanthanum-modified lead titanate (PLT) film was fabricated using sol-gel method on platinized MgO substrates. The substrate used was Pt(100)JTi(100)JMgO where Pt and Ti layers had been sputter-deposited at 600°C. We used the direct furnace insertion method and the crystallization temperature of 700°C in order to fabricate the epitaxial film. The phase of the film was examined using x-ray diffraction (XRD) and the film orientation was examined by pole figure and x-ray rocking curves. The epitaxial PLT thin film had higher dielectric constant and better ferroelectricity and fatigue resistance than the polycrystalline films. However, it shows higher leakage current than the polycrystalline film.     

梯度基体温度法和反应溅射TiC过渡层对钛合金基体沉积金刚石薄膜的影响

以H2和CH4作为反应气体,采用热丝化学气相沉积法(HFCVD)在钛合金(Ti6Al4V)平板基体上制备金刚石薄膜,利用扫描电镜(SEM)、X射线衍射仪(XRD)、激光拉曼光谱(Raman)和洛氏硬度仪分析薄膜的表面形貌、结构、成分和附着性能,研究了高温形核-低温生长的梯度降温法对原始钛合金和反应磁控溅射TiC过渡层的钛合金表面沉积金刚石薄膜的影响。结果表明:原始基体区和TiC过渡层区沉积的金刚石薄膜平均尺寸分别为0.77μm和0.75μm,薄膜内应力分别为-5.85GPa和-4.14GPa,TiC层的引入可以有效提高金刚石的形核密度和晶粒尺寸的均匀性,并减少薄膜残余应力;高温形核-低温生长的梯度降温法可以有效提高金刚石的形核密度和质量,并提高原始基体上沉积金刚石薄膜的附着性能。     

Numerical analysis of the contact stresses developed during the indentation of coated systems with substrates with orthotropic properties

Many works in the literature have analyzed the contact stresses developed during the indentation of coated systems. In general, the damage observed in systems with soft substrates is characterized by circular cone cracks that propagate at the edge of the indentations. In systems with soft substrates, recent works have also shown that the amount of substrate indentation pile-up presents direct relationship with a peak in radial stresses at film surface and, consequently, with the amount of indentation circular cracks.In this work, a series of finite element analyses was conducted to simulate the indentation of systems with an elastic film and an elastic-plastic substrate. Two values of film thickness were selected and, in each simulation, substrates were divided into two layers with different plastic properties. The layer on the bottom was considered isotropic and the layer attached to the film presented plastic properties along the loading direction (z) that were different from the plastic properties along the radial and tangential directions. Different ratios between axial and radial/tangential properties were considered.Results indicated that the amount of substrate pile-up and, consequently, the peak in radial stresses at film surface, could be significantly reduced in coated systems with substrates with orthotropic plastic properties.     

Ru籽晶层对CoCrPt-SiO_2垂直记录层形貌及结构的影响

采用磁控溅射方法,制备了以不同厚度Ru薄膜为籽晶层的CoCrPt-SiO2垂直磁记录薄膜。利用原子力显微镜(AFM)、透射电镜(TEM)分析Ru薄膜的结构和形貌,并研究了其结构对CoCrPt-SiO2薄膜表面形貌、粗糙度及结构的影响。结果表明,CoCrPt-SiO2记录层的晶粒尺寸和粗糙度均随着Ru籽晶层厚度的增加而增加,薄而粗糙的籽晶层适合于高密度磁记录介质。对于CoCrPt-SiO2记录层晶粒的优化,厚度为70nm的Ru籽晶层有利于记录层薄膜晶粒的完全隔离,从而提高了磁记录性能。     

Self-assembly of single-walled carbon nanotube based on diazoresin

The self-assembly film of single-walled carbon nanotube (SWCNT) based on diazoresin (DR) were prepared on CaF₂, mica substrates and Pt tip. After oxidation, the ends of SWCNT were opened and turned into carboxylic group, which can react with diazonium group via Coulombic attraction. The film formed was photosensitive. After UV irradiation, the ionic bond between carboxylic group and diazonium group would turn into covalent bond following the decomposition of the diazonium group. The self-assembly layer and the bond conversion between the layers of the film have been verified with infrared (IR) spectroscopy, UV-Vis spectroscopy and transmission electron microscope (TEM).     

Site-specific synthesis of ZnO nanocrystalline networks via a hydrothermal method

ZnO nanocrystalline networks (NCNWs) consisting of percolating nanocrystals with irregular shape and size were synthesized using Al seed layers in a hydrothermal process. Various thicknesses of Al films were used to assess the effects of film thickness on the formation of ZnO NCNWs; the coverage and size of the ZnO nanocrystals increased with an increasing Al film thickness. In addition, by exploiting the seed layer-dependent crystal growth behaviors, two distinctly different ZnO nanostructures, nanorods on ZnO seed and NCNWs on Al seed, could be selectively achieved on the same substrate under the same growth conditions. Spectrally- and spatially-resolved investigations of these two ZnO nanostructures were performed using cathodoluminescence, which provided a significant opportunity to study the effect of the nanostructures on the luminescent characteristics. The ZnO NCNWs have an extremely high surface to volume ratio and sufficient inter-space, which enabled the conversion of the surface property from hydrophilic to superhydrophobic.     

SUBSTRATE EFFECT ON HYDROGENATED MICROCRYSTALLINE SILICON FILMS DEPOSITED WITH VHF-PECVD TECHNIQUE

Raman spectra and scanning electron microscope （SEM） techniques were used to determine the structural properties of microcrb＇stalline silicon （μc-Si：H） films deposited on different substrates with the very high frequency plasma-enhanced chemical vapor deposition （VHF-PECVD） technique. Using the Raman spectra, the values of crystalline volume fraction Xc and average grain size d are 86%, 12.3nm; 65%, 5.45nm; and 38%, 4.05nm, for single crystalline silicon wafer, coming 7059 glass, and general optical glass substrates, respectively. The SEM images further demonstrate the substrate effect on the film surface roughness. For the single crystalline silicon wafer and Coming 7059 glass, the surfaces of the μc-Si：H films are fairly smooth because of the homogenous growth or h＇ttle lattice mismatch. But for general optical glass, the surface of the μ-Si： H film is very rough, thus the growing surface roughness affects the crystallization process and determines the average grain size of the deposited material. Moreover, with the measurements of thickness, photo and dark conductivity, photosensitivity and activation energy, the substrate effect on the deposition rate, optical and electrical properties of the μc-Si：H thin films have also been investigated. On the basis of the above results, it can be concluded that the substrates affect the initial growing layers acting as a seed for the formation of a crystalline-like material and then the deposition rates, optical and electrical properties are also strongly influenced, hence, deposition parameter optimization is the key method that can be used to obtain a good initial growing layer, to realize the deposition of μc-Si：H films with device-grade quality on cheap substrates such as general glass.     

Effects of various metal seed layers on the surface morphology and structural composition of the electroplated copper layer

This study examined the effects of depositing a seed layer on the surface morphology and the electric characteristics of an electrodeposited copper foil. Pt, Pd, a Pt-17Pd alloy and gold were used as the seed metals. The morphology, crystal structure, and electric characteristics of the electrodeposited copper foil were examined by scanning electron microscopy, X-ray diffraction, atomic force microscopy, and a four-point probe, respectively. The surface roughness, crystal growth orientation, and resistivity were controlled using various seed layers. Large particles were observed on the surface of the copper layer electroplated onto the Pd seed layer. However, a uniform surface was obtained when a Pt seed layer was used.