Polytype transformations in SiC-epitaxial layers: The color cathodoluminescence-sem studies

The polytype transformation in SiC-epitaxial layers grown by the sublimation “sandwich method” have been studied by means of a real color SEM cathodoluminescence (CL) technique. The variation of polytypes grown on 6H-, 4H-, 15R-, and 21R-polytype substrates is demonstrated. Different spectral composition of local CL emission is observed on smooth and profiled substrate surfaces. The double polytype transformation effect was fixed. The nature of the polytype transformation in SiC epitaxial layers is discussed.     

溶胶－凝胶法在金属表面制备TiO_2－SiO_2系薄膜的研究

本文介绍以钛酸丁酯和正硅酸乙酯为前驱物、用溶胶。凝胶法在不锈钢金属基体表面制备晶态或非晶态的ＴｉＯ＿２－ＳｉＯ＿２系薄膜，ＩＲ测定结果表明有硅。氧－钛网络形成，并对薄膜进行了ＸＲＤ和ＳＥＭ观察。研究结果表明，在不锈钢金属基体上用溶胶－凝胶法选取适当条件可以得到附着力良好以及均匀完整的多种无机物薄膜，显示了该法的应用前景。     

Growth and defects of GaAs and InGaAs films on porous GaAs substrates

We investigated the opportunities to increase the electric uniformity of GaAs and InGaAs films grown by molecular-beam epitaxy (MBE) technique on monocrystalline (single crystal) GaAs: both on porous and conventional so-called “monolithic” (without pores) GaAs (100) substrates. The basic attention was given to study the electrically active defects in films by using scanning electron microscope (SEM) with new technique which is called “Rau-detector” [E.I. Rau, A.N. Zhukov and E.B. Yakimov, Solid-State Phenomena, 1998, v. 53-54, 327.]. We compared the main properties of epitaxial GaAs and InGaAs films grown on above mentioned substrates. The films grown on porous substrates had higher structural perfection including the following advantages: (a) smoother surface due to lateral growth mechanism; (b) less density of structural defects (without dislocation walls), the density of pyramidal defects was ∼ 2 × 10⁵ cm^− 2 as compared with the density 2 × 10⁷ cm^− 2 in the films grown on monolithic substrates; (c) less electrical activity of various structural defects and increased electric uniformity of grown films. The electrical activity of defects in films grown on porous substrates was essentially lowered due to gettering properties of porous substrate.     

AlN基片氧化及金属化

研究了 Al N陶瓷高温氧化对金属化结合强度的影响。在 80 0℃、 10 0 0℃、 12 0 0℃和 140 0℃下对 Al N基片进行了高温处理 ,并用 XRD和 SEM分析了氧化结果。从 12 0 0℃开始 ,基片表面有较明显的氧化 ,140 0℃时 ,基片内部氧化明显。在氧化后的 Al N基片上金属化布线 ,发现表面轻微氧化的 Al N基片和金属化强度有一些提高 ,但氧化过度 ,反而会使金属化结合强度大幅度下降。     

Natural Materials for Sustainable Organic Solar Cells: Status and Challenge

The exploitation of natural materials has received growing attention because of the needs of environmental sustainability. In contrast to petroleum-based synthetic materials, natural materials possess significant advantages of abundant, low-cost, degradable, and renewable. Here, the recent research status of natural materials as flexible substrate, cathode interfacial material, and anode interfacial material for organic photovoltaics (OPVs) are first presented. Then, the confronted key challenges that limit the widespread application of natural materials for OPVs is summarized, including complex multilength scaled aggregation morphology, non-conjugated structure, and unclear working mechanism. Finally, their potential solutions from the perspective of chemical structure are proposed for constructing efficient OPVs. It is believed that natural materials have a broad landscape in low-cost and green manufacturing technology for OPVs in the future.     

Development of metal supported solid oxide fuel cells based on powder metallurgical manufacturing route

Abstract

In the past few decades, stationary solid oxide fuel cell (SOFC) systems have been developed that can generate electricity and heat from the energy stored in hydrogen or hydrocarbons with total efficiencies up to 95%. While the mechanical cell support of stationary systems is commonly supplied by thick ceramic cell components (i.e. anode and electrolyte supported concepts), mobile systems demand a more robust design. This is ensured by a strong yet porous metallic substrate which serves as the mechanical backbone of thin film membrane electrode assemblies [metal supported cell (MSC) concept]. Porous PM Fe–Cr oxide dispersion strengthened alloys for use as MSC supports have recently been developed. These materials provide mechanical and chemical long term stability in typical SOFC atmospheres at operation temperatures up to 850°C. The substrates support a multilayer anode–electrolyte–cathode thin film assembly, constituting a high performance MSC repeat unit. These units are the building blocks for MSC stacks with superior properties for mobile applications.     

Microbiota in anaerobic digestion of sewage sludge with and without co‐substrates

In this study, seven full‐scale anaerobic digesters, with or without co‐substrate regime, were analysed by physicochemical and molecular biological methods. A combination of robust community fingerprinting and Illumina MiSeq sequencing revealed a core bacterial community dominated by Chloroflexi, Firmicutes, Bacteroidetes and Proteobacteria, with variations in the profiles because of differences in the co‐substrate feeding regime. Despite these differences, physicochemical properties revealed a stable performance of all reactors, indicating a resilient bacterial microbiota in all full‐scale reactors. A rich bacterial core community ensured reactor functionality, whilst feeding regime and reactor type impacted the overall and the core bacterial diversity. Within the Archaea, Methanosaeta dominated in all reactors. Results indicated no relationship between archaeal community structure and the type of co‐substrate digested. Methanogens rely on the metabolic end products of bacterial activity and are thus less dependent on differences in the initial co‐substrate regime.     

Utilization of geometric light trapping in thin film silicon solar cells: simulations and experiments

In this study, we present a new light absorption enhancement method for p‐i‐n thin film silicon solar cells using pyramidal surface structures, larger than the wavelength of visible light. Calculations show a maximum possible current enhancement of 45% compared with cells on a flat substrate. We deposited amorphous silicon (a‐Si) thin film solar cells directly onto periodically pyramidal‐structured polycarbonate (PC) substrates, which show a significant increase (30%) in short‐circuit current over reference cells deposited on flat glass substrates. The current of the cells on our pyramidal structures on PC is only slightly lower than that of cells on Asahi U‐type TCO glass (Asahi Glass Co., Tokyo, Japan), but suffer from a somewhat lower open circuit voltage and fill factor. Because the used substrates have a locally flat surface area due to the fabrication process, we believe that the current enhancement in the cells on structured PC can be increased using larger or more closely spaced pyramids, which can have a smaller flat surface area. Copyright © 2012 John Wiley & Sons, Ltd.     

Fluorogenic peptide-based substrates for monitoring thrombin activity

The synthesis of a series of peptides containing C‐terminal 7‐amino‐4‐methylcoumarin (AMC) for use in the thrombin generation test (TGT) is described. The lead structure in this project was H‐Gly‐Gly‐Arg‐AMC, of which the water solubility and kinetic parameters (K_M and k_cat) are greatly improved over those of the substrate in current use in the TGT: Cbz‐Gly‐Gly‐Arg‐AMC. A series of N‐terminally substituted Gly‐Gly‐Arg‐AMC derivatives were synthesized, as well as implementation of structural changes at either the P₂ or P₃ position of the peptide backbone. Furthermore, two substrates were synthesized that have structural similarities to the chromogenic thrombin substrate SQ68 or that contain a 1,2,3‐triazole moiety in the peptide chain, mimicking an amide bond. To determine the applicability of newly synthesized fluorogenic substrates for monitoring continuous thrombin generation, the K_M and k_cat values of the conversion of these fluorogenic substrates by thrombin (FIIa) and factor Xa (FXa) were quantified. An initial selection was made on basis of these data, and suitable substrates were further evaluated as substrates in the thrombin generation assay. Assessment of the acquired data showed that several substrates, including the SQ68 derivative Et‐malonate‐Gly‐Arg‐AMC and N‐functionalized Gly‐Gly‐Arg‐AMC derivatives, are suitable candidates for replacement of the substrate currently in use.