New generalized computations of quasi-planar waveguides characteristics

An efficient hybrid field solution to the general multilayer substrates transmission line problems with full shielded and half open cross-sectional geometry is presented by using the waveguide modes coupling and decoupling procedure in the spectral domain. Modal transverse transmission lines corresponding to the LSE and LSM modes are taken into account so that the Green's elements for the edge conditions can be derived by a simple iterative method. In this paper, we analyze not only the propagation constants and characteristic impedances but also the available transmission power capacity and power distribution of most commonly used structures. Normalized eigenmode power levels characterizing the propagation features are computed.     

Photocatalysed eosin Y mediated C(sp3)-H alkylation of amine substrates via direct HAT

A visible light promoted, photoredox catalysed, green one-pot approach for the alkylation of amine substrates with sp² carbon has been developed. This eosin Y based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for coupling reaction. The proposed strategy includes simple procedure which can make adduct product with sp² carbon. This eosin Y based photocatalytic hydrogen-atom transfer strategy may hold great potential for diverse functionalization of a wide range of native CH bonds in an economical and sustainable manner.     

Paving the Way for High-Performance UVB-LEDs Through Substrate-Dominated Strain-Modulation

AlGaN-based ultraviolet-B light-emitting diodes (UVB-LEDs) exhibit great potential in phototherapy, vitamin D3 synthesis promotion, plant growth regulation, and so on. However, subjected to the excess compressive strain induced by the large lattice mismatch between multiple quantum wells (MQWs) and AlN, UVB-LEDs that simultaneously satisfy the requirements of high light output power (LOP), low working voltage, and excellent stability are rarely reported. Here, a substrate-dominated strain-modulation strategy is proposed. By precisely manipulating the strain in AlN grown on nano-patterned sapphire substrate (NPSS) to a slightly tensile one, the compressive strain in the following Al_0.55Ga_0.45N underlayer and Al_0.28Ga_0.72N/Al_0.45Ga_0.55N MQWs is successfully suppressed. As a result, an outstanding UVB-LED with a peak wavelength at 303.6 nm is achieved. The 20 × 20 mil² UVB-LED chip shows a wall-plug efficiency (WPE) of 3.27% under a forward current of 20 mA and a high LOP of 57.2 mW with an extremely low voltage of 5.87 V under a forward current of 800 mA. It is more exciting that the LOP degradation is as low as 17% after 1000 h operation under a forward current density of 75 A cm⁻², showing excellent stability. The here-developed UVB-LED, with a high LOP and excellent reliability, will definitely promote the applications of AlGaN-based UVB-LEDs.     

Reactions of fluorinated acid anhydrides, (CF3CO)2O, (CF3SO2)2O and (FSO2)2O, with organometallic substrates of group 15 (As, Sb and Bi)

(C₆H₅)₃MX₂ (M = As, Sb; X = OCOCF₃ and M = Sb, Bi; X = SO₃F, SO₃CF₃) compounds prepared by the interaction of triphenylmetal(V) substrates with (CF₃CO)₂O, (CF₃SO₂)₂O and (FSO₂)₂O have been characterized by molecular weight determination, elemental and spectroscopic (IR, ¹H and ¹⁹F NMR, mass) analyses.     

Template functions of particle monolayers on hydrophobic solid substrates

The template function of cationic particle monolayers bearing quaternary ammonium groups on their surfaces towards anionic colloids was investigated in this paper. Monodispersed cationic polymer particles having quaternary ammonium groups were self-organized on octadecylated glass plates through hydrophobic interaction. The morphology of the resulting particle monolayers was changed by tuning hydrophilic–hydrophobic balance of particles to fabricate aggregated type and dispersed type of particle monolayers. Gold and silver colloids were selectively deposited onto the particle monolayers through electrostatic interaction. The deposited gold and silver colloids on particle monolayers showed plasmon absorbance. Fluorescent silica colloids were also selectively deposited on particle monolayers to permit fluorescence labeling of the particle monolayers. Cationic particle monolayers fabricated on hydrophobic solid octadecylated were found to effectively work as templates for the deposition of above mentioned inorganic colloids.     

LTCC基板制造工艺研究

低温共烧多层陶瓷（ＬＴＣＣ）基板是制造复杂微电子产品多芯片组件（ＭＣＭ）的重要部件。详细地讨论了ＬＴＣＣ基板制造工艺，介绍了多年研究之经验及国外的有关技术，还指出了目前工艺中存在的技术问题及在工艺水平上与国外的差距。采用目前工艺，可做出２０层布线、线宽及间距均为０．２０ｍｍ、８０ｍｍ×８０ｍｍ的多层共烧基板     

Flexible rewritable organic memory devices using nitrogen-doped CNTs/PEDOT:PSS composites

Nonvolatile rewritable organic memory devices based on poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and nitrogen doped multi-walled carbon nanotube (NCNT) nanocomposites were fabricated on glass and PET substrates.Organic memory devices with bistable resistive switching were obtained using very low NCTN concentration (∼0.002 wt%) in the polymeric matrix. The memory devices exhibited a good ON/OFF ratio of approximately three orders of magnitude, a good retention time of 10⁴ s under operating voltages ≤ |4V| and a few hundredths of write-read-erase-read cycles. The bistable resistive switching is mainly attributed to the creation of oxygen vacancies. These defects are introduced into the thin native Al oxide (AlOx) layer on the bottom electrode during the first voltage sweep. The well-dispersed NCNTs immersed in PEDOT:PSS play a key role as conductive channels for the electronic transport, hindering the electron trapping at the AlOx-polymer interface and inducing a soft dielectric breakdown of the AlOx layer. These PEDOT:PSS + NCNTs memory devices are to easy to apply in flexible low-cost technology and provide the possibility of large-scale integration.     

A low-temperature X-ray diffraction study of the Cu2ZnSnSe4 thin films

Low-temperature XRD measurements were performed to confirm the phase composition and structural parameters of the electrochemically deposited Cu₂ZnSnSe₄ thin films on flexible metal substrates.     

Low temperature hermetic laser-assisted glass frit encapsulation of soda-lime glass substrates

Room temperature and low temperature (120 °C) laser-assisted glass frit bonding of soda-lime glass substrates are accomplished in this work. The locally laser melted bonding showed hermeticity with helium leak rate of <5×10⁻⁸ atm cm³ s⁻¹, maintaining its leak rate even after standard climatic cycle tests. Small size devices were bonded at room temperature while larger areas were sealed at the process temperature of 120 °C. The sealing parameters were optimized through response surface methodology that makes the process capable for further development regardless of device size.