Optical and thermal properties of large-area OLED lightings with metallic grids

We investigate the effects of auxiliary metal electrodes on the optical and thermal properties of large-area (30 × 120 mm²) opaque and transparent white OLED lighting panels. Enlarging their emission area inevitably entails a non-uniform current distribution due to the limiting conductivity of transparent electrodes, causing local heat generation. To tackle it, we have used grid patterned Cr, Mo/Al/Mo, or Cu metal lines (0.15 mm in width) as auxiliary metal electrodes on an ITO anode. Among those, Cu metal grids exhibit the highest luminous efficacy with the least heat generation, and the most uniform light distribution by virtue of its lowest sheet resistance, followed by Mo/Al/Mo and then Cr metal grids. It is also found that local heat generation appears more seriously in large-area transparent OLED panels. With attempt to suppress it, we have also deposited Al metal lines (2 mm in width) on a semitransparent Al/Ag cathode by thermal evaporation, which brings in a highly uniform heat distribution. Furthermore, we study the effect of the shape of the light-emitting area on the luminance and heat distributions. A round-shaped OLED panel with a hexagonal metal grid exhibits highly homogeneous luminance and surface temperature distributions.     

Optical properties of metallic quantum wells

The authors model the optical properties of metallic quantum wells with thicknesses in the range of a few nanometers. A simple picture that includes only single electron transitions predicts strong absorption lines at frequencies associated with allowed interband transitions. This strong absorption feature can be in the near infrared for metal films several monolayers thick. The model is extended to include collective electron interactions by solving simultaneously Schroedinger's and Poisson's equations. It is found that the single electron picture does not change appreciably for frequencies above the bulk plasma frequency of the metal. For frequencies at or below the plasma frequency, however, the absorption is reduced in strength and becomes nearly featureless     

Reflection properties of a phase modulating planar screen

The reflection properties of a phase modulating planar structure are examined. The structure consists of an active microwave screen placed in front of a conducting surface. Switching the screen between fully transparent and totally reflective states results in a phase modulated reflected signal with reduced energy at the illuminating frequency. Both single and multilayer configurations are examined     

Sensitivity of a wide-band F.I.R. receiver using a Josephson self oscillator mixer

The system temperature of a receiver using a Josephson junction as a self oscillator mixer has been measured in the range 0.6 to 2 THz. The experimental value T_S=53000K (DSB) at 900 GHz is in good agreement with the calculated value. A T_S～12 000 K is predicted with a 30 K i.f. amplifier Possible applications are related to fast frequency tunable receivers (over one octave) with limited spectral resolution.     

射频磁控溅射法制备SnO2:Sb透明导电薄膜的光电性能研究

采用射频磁控溅射法在载波片玻璃衬底上制备了锑掺杂二氧化锡(SnO2Sb)透明导电薄膜.利用霍耳效应实验、紫外可见光光谱仪、n(折射率)k(消光系数)d(薄膜厚度)光谱仪对该导电薄膜的光电性能进行了测试.讨论了氧气分压对样品光电性能的影响,增加氧气分压,薄膜的厚度减小、吸收边和截止波长蓝移,光学带隙增大,并且氧气分压对薄膜电阻率、载流子浓度和霍耳迁移率的影响不是线性的,而是存在一个最佳值.当氧气分压为0.10 Pa时,薄膜的光电性能最佳,此时膜厚为399 nm,可见光平均透过率为70 %,电阻率为2.5×10-3 Ω·cm,载流子浓度为1.2×1021 cm-3,载流子霍耳迁移率为2.04 cm2·V-1·s-1,其光电特性已达到了TFT-LCD透明电极的要求.     

A study of the apparatus function of a grid Fabry-Perot interferometer used as a F.I.R. spectrometer: Computing of the spectrum

Influences of various parameters on the apparatus function of a F.I.R. grid Fabry-Perot spectrometer are analysed. A pseudo-deconvolution method allowing an improvement of experimental results is tested by simulation and then applied to data concerning the isotopic HCl doublet at 41 cm^?1.     

Optical properties of gallium nitride bulk crystals grown by chloride vapor phase epitaxy

The optical properties of bulk crystals of gallium nitride grown by chloride vapor-phase epitaxy are investigated. It is shown that these crystals exhibit exciton luminescence bands. Analysis of the energy positions of the band maxima imply certain conclusions about the presence or absence of mechanical stresses in the bulk crystals of GaN obtained. Analysis of the luminescence spectra also reveals that the temperature dependence of the width of the GaN band gap E _g in the temperature range T=6–600 K is well described by the expression E _g (T)=3.51−7.4×10⁻⁴ T ²(T+600)⁻¹ eV. It is estimated that values of the free electron concentration in these crystals do not exceed 10¹⁸ cm⁻³. The optical characteristics of the bulk GaN crystals are compared analytically with literature data on bulk crystals and epitaxial layers of GaN grown by various methods. Fiz. Tekh. Poluprovodn. 33, 1173–1178 (October 1999)     

Absolute measurement at 1 THz of the optical coupling of a F.I.R. conical antenna with a Josephson detector

We present the first absolute measurement of the optical coupling of a FIR antenna with a Josephson detector. We have studied a wide band FIR coupling system made of a conical antenna (discone) and a focussing paraboloid mirror. The calculated efficiency is (6.8±0.3)10^?2 for the optimum choice of parameters at 1 THz. The best measurements using a HCN laser at 891 GHz are in agreement while the average achieved coupling is (2.3±0.4)10^?2 reflecting the experimental difficulties.     

R.I.P.: Remain in perpetuity. Facebook memorial pages

Facebook is not only a virtual space to commune with the living, it is also a place to honor, memorialize, and engage in dialogs with the deceased. This study examines 550 memorial pages on Facebook for age, gender, race, and cause of death of the memorialized, as well as to whom the communication is addressed. Where ritualistic memorials and mourning practices usually occur in cemeteries or at the sites of accidents, memorial sites on Facebook offer an alternative space to mourn that is public, collective, and with archival capabilities. Individual dialogs and memories in this alternative space are not private, and often involve direct communications with the deceased. In this way, the dead never really die; rather perpetually remain in a digital state of dialogic limbo.     

A new approach to diffraction analysis of conductor grids. I.Parallel-polarized incident plane waves

Diffraction analysis is presented for infinite planar conducting-cylinder grids illuminated by normally incident (parallel-polarized) plane waves, the electric fields of which are parallel to the cylinder axes. The Green's function kernel integral equations are used for the induced currents, which are based on the equivalent waveguide theory and solved for the currents by the moment method. This is a universal analysis approach, applicable to infinite planar grids made of conducting cylinders of arbitrary cross section, uniform or periodic, dense or sparse, single layer or multilayer     

Optical properties and recombination mechanisms in GaN and GaN:Mg grown by metalorganic vapor phase epitaxy

Photoluminescence (PL) and reflection spectra of undoped and Mg-doped GaN single layers grown on sapphire substrates by metalorganic vapor phase epitaxy (MOVPE) were investigated in a wide range of temperatures, excitation intensities, and doping levels. The undoped layers show n-type conductivity (μ=400 cm²/Vs, n=3×10¹⁷ cm⁻³). After annealing at T=600–700°C, the Mg-doped layers showed p-type conductivity determined by the potential-profiling technique. A small value of the full width at half maximum (FWHM=2.8 meV) of the excitonic emission and a high ratio between excitonic and deep level emission (≈5300) are evidences of the high layer quality. Two donor centers with activation energies of 35 and 22 meV were observed in undoped layers. A fine structure of the PL band with two narrow lines in the spectral range of the donor-acceptor pair (DAP) recombination was found in undoped layers. An anomaly was established in the temperature behavior of two groups of PL lines in the acceptor-bound exciton and in donor-acceptor pair regions in Mg doped layers. The lower energy line quenched with increasing temperature appreciably faster than the high energy ones. Our data does not agree with the DAP recombination model. It suggests that new approaches are required to explain the recombination mechanisms in undoped and Mg-doped GaN epitaxial layers.     

相变记录介质Sb_2Se_3薄膜的光学性质和微观结构

采用热蒸发制备了非晶态Sb_2Se_3薄膜。系统地研究了真空热退火对Sb_2Se_3薄膜光学性质和微观结构的影响。     

Properties of conducting zinc oxide films prepared by R.F. Sputtering

An effective method of dopant incorporation in rf sputtered ZnO film is reported. The electrical, optical and structural properties of zinc doped ZnO films are investigated. Electron mobility of∼10 cm² /V-sec and electron concentration of∼10¹⁹ cm⁻³ have been measured at room temperature. X-ray diffraction data obtained on films prepared on Corning 7059 glass show (002) peak, dominating. The high electrical conductivity and transmission makes ZnO films very attractive as a component for heterojunction solar cells.     

Heterodyne frequency measurements of COF2, CD3F,13CD3F,and C2H5I lasers

Heterodyne frequency measurements are reported for twenty optically pumped laser lines from various molecules including COF₂, CD₃F,¹³CD₃F, and C₂H₅I.     

射频溅射CoMnNiO非晶薄膜中空穴的迁移率

测量薄膜的热电动势,很容易确定薄膜中载流子的迁移率。本研究根据CoMnNiO非晶薄膜在200—350K温区的热电动势测量和直流电导,计算了薄膜中空穴的迁移率。结果表明,330K时,薄膜中空穴的迁移率为1.25cm~2v~(-1)(?)~(-1),且具有热激活性质。由此可以推断,射频溅射CoMnNiO非晶薄膜在常温下发生跳跃导电。