Interface modification effect between p-type a-SiC:H and ZnO:Al in p-i-n amorphous silicon solar cells

Aluminum-doped zinc oxide (ZnO:Al) [AZO] is a good candidate to be used as a transparent conducting oxide [TCO]. For solar cells having a hydrogenated amorphous silicon carbide [a-SiC:H] or hydrogenated amorphous silicon [a-Si:H] window layer, the use of the AZO as TCO results in a deterioration of fill factor [FF], so fluorine-doped tin oxide (Sn0₂:F) [FTO] is usually preferred as a TCO. In this study, interface engineering is carried out at the AZO and p-type a-SiC:H interface to obtain a better solar cell performance without loss in the FF. The abrupt potential barrier at the interface of AZO and p-type a-SiC:H is made gradual by inserting a buffer layer. A few-nanometer-thick nanocrystalline silicon buffer layer between the AZO and a-SiC:H enhances the FF from 67% to 73% and the efficiency from 7.30% to 8.18%. Further improvements in the solar cell performance are expected through optimization of cell structures and doping levels.     

Enhanced photocatalytic performance of Bi2Fe4O9/graphene via modifying graphene composite

Bi₂Fe₄O₉ (BFO) is one of the most important photocatalyst materials and its composition with graphene may leave an optimizing effect on the photocatalytic performance. In this paper, reduced graphene oxide (RGO) with various contents is selected to be composited with BFO successfully via one‐step hydrothermal method. A series of BFO‐xRGO (x=0, 1.25, 2.50, 3.75, 5, 6.25, and 7.50 wt.%) were prepared and the effects of RGO content on crystalline, light absorption, impedance, and photocatalytic degradation rate of methyl violet (MV) solution are characterized. The entire film samples exhibit enhanced photocatalytic efficiency. Especially, with 5 wt.% RGO content added, the film sample shows the best photocatalytic degradation efficiency with a MV solution degradation rate of 95%. This implies that the composition of RGO allows BFO‐based thin film as an efficient photocatalyst candidate, and as well, the BFO/RGO composite possesses the potential for better use in the related photocatalyst applications.     

Plasma polymerization of trimethylsilane in cascade arc discharge

Plasma polymerization of trimethylsilane (TMS) in cascade arc discharge was experimentally investigated. It was found that the deposition rates of methane and TMS plasma polymer were dependent on plasma parameters, and the surface characteristics of plasma polymer were also dependent on plasma variables. The following plasma variables were studied: arc current, argon flow rate, TMS flow rate, chamber pressure, substrate axial, and radial positions. Carbon, silicon, and oxygen were the main elements observed in TMS polymer films obtained by x-ray photoelectron spectroscopy (XPS). Powder-like TMS polymer films were observed by scanning electron microscopy (SEM). The size distribution of the powder-like particles was strongly dependent on deposition parameters. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1653–1665, 1997     

Laser annealing and surface modification of plasma polymer-metal composite films

Plasma polymer films with encapsulated metal particles were prepared by simultaneous plasma polymerization and metal evaporation. Laser annealing (Nd-YAG, 1064 nm) causes dramatic changes in the particle size and shape without material ablation, but with changes in the surface topography. This results in changes in the optical plasma resonance absorption, as demonstrated by UV-visible-near-infrared (NIR) spectroscopy. The invariable transmission in the UV region of the plasma polymer matrix after laser annealing confirms that there is no material ablation. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) demonstrated particle size changes and modifications of the plasma polymer surface due to laser annealing.     

Luster Pottery from the Thirteenth Century to the Sixteenth Century: A Nanostructured Thin Metallic Film

Luster is a decorative metallic film that was applied on the surface of medieval glazed pottery. It can be obtained via the low-temperature (∼650°C), controlled reduction of copper and silver compounds. In this paper, we show that luster is a thin layered film (200–500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10–20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5–100 μm in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Luster is indeed the first reproducible nanostructured thin metallic film that was made by humans.     

DC—PCVD法快速制备Si3N4薄膜

采用ＤＣ－ＰＣＶＤ方法，控制工艺参数，在ＧＣｒ１５钢试样上获得４０μｍ厚的，以Ｓｉ３Ｎ４为主要成分的非晶态绝缘薄膜，沉积速率约为３７Ａ／ｓ，讨论了沉积速率高的原因。     

等离子体增强化学气相沉积法制备氢化硅膜的自晶化倾向性

为了探寻生长过程中硅膜的自晶化沉积,采用等离子体增强化学气相沉积(PECVD)法沉积了氢化硅薄膜,系统研究了不同沉积阶段所得硅膜微观结构的迁变规律。结果表明,硅膜的显微结构依赖于沉积时间,当沉积时间仅为30min时,所得硅膜的结构为非晶;而当沉积时间延至60min时,硅膜形成微晶颗粒;此后随着沉积时间的增加,晶化程度提高,且非晶区域面积相应减小。另外,硅膜的沉积速率也随沉积时间的增加而增加。在硅膜沉积过程中,随时间不断变化的界面状态可能为其自晶化的主要原因。     

Nanostructured Silicon Oxide–Nickel Oxide Sol–Gel Films with Enhanced Optical Carbon Monoxide Gas Sensitivity

Sol–gel derived silica (SiO₂) films doped with nickel oxide (NiO) nanocrystals were fabricated. A bifunctional ligand was used, bearing amine groups capable of coordinating the nickel ions and hydrolysable siloxane groups for anchoring the metal complex moiety to the silicate matrix. Nickel oxide nanocrystals precipitated at 500°C while the film was still porous. The nanocomposite films showed a reversible change in the optical transmittance in the VIS-NIR range when exposed to carbon monoxide gas. The effects of residual porosity, testing temperature, and carbon monoxide gas concentration on optical transmittance were studied.     

有序介孔二氧化硅薄膜的制备及性能

以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯为无机前驱体,在酸性条件下,采用溶胶-凝胶技术,用蒸发诱导自组装(EISA)工艺制备了二氧化硅透明介孔薄膜. 透射电子显微镜图显示热处理后的薄膜具有高度有序的六方相结构孔道;由椭偏仪测得热处理后薄膜的折射率低至1.18,厚度在180 nm左右;阻抗分析仪测得薄膜的介电常数为2.14. 薄膜经过六甲基二硅胺烷(HMDS)表面修饰后具有良好的疏水性能和热稳定性,作为低介电材料能更好满足工业需求.     

Mimicking Nanometer Atomic Processes on a Micrometer Scale via Electrophoretic Deposition

The process of submonolayer formation during the electrophoretic deposition (EPD) of colloidal films of micrometer-sized (diameter ∼ 0.5 μm) silica particles on a silicon wafer has been observed as a function of deposition time. The process of nucleation and growth of the silica monolayer is compared with that of atomic film growth (10000 times smaller scale) via molecular-beam epitaxy (MBE), and for the first time, a striking similarity between the two growth processes is observed. Likewise in the atomic growth process via MBE, the entire nucleation, growth, and aggregation process during EPD of silica particles can be broadly classified into two regions. At low surface coverage when silica particles are deposited outside of clusters, diffuse randomly, and stick to a cluster on touching them, the mechanism of growth in this region follows diffusion-limited aggregation (DLA) and the fractal dimension of the two-dimensional clusters is found to be close to 1.65. Later on, as the clusters grow in size, deposition of particles inside the clusters become important and clusters become more and more compact, resulting in a dense, close-packed, and homogeneous monolayer. This region is termed a consolidation region, and a change in fractal dimension from 1.65 toward 2 with increasing surface coverage has been observed.     

气相法制备ZnS薄膜材料研究进展

综述了近几年ZnS薄膜材料的气相沉积制备方法及其应用,主要讨论了真空蒸发、磁控溅射、脉冲激光沉积、分子束外延、金属有机物化学气相沉积、原子层沉积等制备方法的最新研究进展,指出了ZnS薄膜的各种气相沉积方法的优点和不足以及今后的发展趋势。     

Synthesis of Sr2Nb3O10 nanosheets and their application for growth of thin film using an electrophoretic method

K(Sr₂Nb₃)O₁₀ (KSN) ceramic without the secondary phase was obtained from a KSN + 0.05K₂O specimen sintered at 1350°C. This ceramic was used as the precursor to synthesize Sr₂Nb₃O₁₀^? (SNO^?) nanosheets, because it has a pure KSN phase with a large (002) plane. The SNO^? nanosheets were deposited on a Pt/Ti/SiO₂/Si substrate using the electrophoresis method at room temperature, and heated at various temperatures to get rid of the organic defects. The crystalline SNO phase without organic defects was formed in film annealed at 600°C. However, when the annealing temperature exceeded 600°C, the Pt electrode became unstable, resulting in degradation of the SNO film. Good electric properties were obtained from the SNO film annealed at 600°C: dielectric constant of 70, dielectric loss of 0.017 at 1.0 MHz, leakage current density of 3.5×10^?8 A/cm² at 0.2 MV/cm, and a breakdown electric field of 0.25 MV/cm.     

Effects of indenter angle on micro‐scale fracture toughness measurement by pillar splitting

We present improvements to a recently developed pillar splitting technique that can be used to characterize the fracture toughness of materials at the micrometer scale. Micro‐pillars with different aspect ratios were milled from bulk Si (100) and TiN and CrN thin films, and pillar splitting tests were carried out using four different triangular pyramidal indenters with centerline‐to‐face angles varying from 35.3° to 65.3°. Cohesive zone finite element modeling (CZ‐FEM) was used to evaluate the effect of different material parameters and indenter geometries on the splitting behavior. Pillar splitting experiments revealed a linear relationship between the splitting load and the indenter angle, while CZ‐FEM simulations provided the dimensionless coefficients needed to estimate the fracture toughness from the splitting load. The results provide novel insights into the fracture toughness of materials at small‐scales using the pillar spitting technique and provide a simple and reliable way to measure fracture toughness over a broad range of material properties.     

类金刚石膜的结构与性能研究

用激光Ｒａｍａｎ谱和ＸＲＤ谱对用直流－射频等离子体化学气相沉积法制备的类金刚石膜的结构进行了分析，并研究了工艺参数对膜的沉积速率，内应力和直流电阻率的影响，结果表明，类金刚石膜是由ｓｐ＾２和ｓｐ＾３键组成的非晶态碳膜，当负偏压高于３００Ｖ时，膜中ｓｐ＾３／ｓｐ＾２键的比值随负偏压的升高而降低，类金刚膜的沉积速率与负偏压Ｖｂ的成正比，膜内存在１～４．７ＧＰａ的压应力，随负偏压的升高而降低，膜的电阻率     

甲烷浓度对金刚石薄膜(100)织构生长的影响

以H2和CH4的混合气体为气源,用微波等离子体辅助化学气相沉积法(MPECVD)在1 cm×1 cm S i(100)基体上沉积了金刚石薄膜。研究了不同的甲烷浓度对金刚石薄膜(100)织构生长趋势的影响。分别采用扫描电子显微镜(SEM),Ram an光谱对金刚石膜的表面形貌、质量进行了分析。结果表明,当基体温度为750℃,气压为4.8×103Pa,甲烷浓度为1.4%时,薄膜表面为(100)织构。