最新刊期
卷 33 ， 期 6 ， 2012
- 摘要：Yb3+-Er3+-codoped fluoride samples were synthesized by using solid-state reaction method. Upconversion emission characters were investingated under 980 nm laser diode excitation. It was found that the upconversion spectra depended on excited power when Yb3+-doped content was more than 10%. According to various concentration of rear-earth ions, an upconversion process with time-delayed sequential two-phonon energy tansfer was proposed, which can be able to explain the phenomenon satisfactorily.关键词：rare-earth;near-infrared excitation;upconversion emission76|46|2更新时间：2020-08-12
- 摘要：In this work, the steady-state photoluminescence (PL) and time-resolved photoluminescence(TRPL) of polycrystalline CdTe on different substrates were measured at room temperature by a Nd:YAG picosecond laser as the excitation source. With the increasing of pump power, the PL spectra have been broadened towards high photon energy. The PL spectra of the annealed sample exhibit another small band, which is attributed to the donor-acceptor pair recombination by a chlorine donor and a cadmium vacancy complex acceptor. The PL decay curve presents bi-exponential processes. The processes with long and short lifetimes are related to surface trapping state and band-edge excitonic state, respectively. Annealing treatment makes the fluorescence lifetime longer and benefits for the separation of the electron-hole pair before being composited.关键词：CdTe;annealing;photoluminescence;fluorescence lifetime78|452|0更新时间：2020-08-12
- 摘要：With the Si/Al doping quantity increasing, the intensity of the BaO-(1-x)SiO2-xAl2O3-B2O3-0.005Er3+(x=0,0.5,1,mole fraction) glass samples show the opposite trend at 1 540 nm infrared emitting and 540 nm up-conversion luminescence. We discuss the internal relation between the rare earth ion’s peripheral micro structure and fluorescence behavior. The process of electron transition for up-conversion and infrared emitting are illustrated by the energy diagram.Infrared FTIR transmission spectra show that the maximum phonon energy does not significantly change with the doping concentration. This indicates that the change of spectrum in different concentration is not derived from the influence of the maximum phonon energy. The calculation by Judd-Ofelt theroy shows that the local symmetry around rare earth ions varies with doping quantity of Al3+/Si4+. Radiative decay rates(A), the radiative lifetime(τ), fluorescence branching ratios(β), and stimulated emission cross section(σ) for 540 nm and 1.54 μm are calculated. The results show that the changes are opposite. Finally, the fluorescence decaying curves of 4I13/2-4I15/2 for Er3+ in the borate glass samples are characterized,which is consistent with the experimental results.关键词：borate glass;infrared luminescence;up-conversion luminescence;Judd-Ofelt theory106|120|0更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：The effect of nitridation treatment and the low temperature (LT) AlN buffer on structure and strain of a-plane GaN epilayers grown on r-plane sapphire by low pressure metalorganic chemical vapor deposition (LP-MOCVD) has been investigated by high resolution X-ray diffraction (HRXRD) and polarized Raman scattering spectra in backscattering configurations. For the sample using the LT-AlN buffer, the full widths at half maximum (FWHM) of X-ray rocking curves (XRC) and the strain of a-plane GaN are lower comparing with that of the sample with nitridation, which is consistent with the smaller in-plane stress anisotropic distribution in a-plane GaN epilayers with LT-AlN buffer.关键词：a-GaN;anisotropic;Raman spectroscopy;strain92|51|0更新时间：2020-08-12
- 摘要：A novel red Sr2ZnMoO6:Sm3+ phosphor was prepared by solid state reaction method, and its luminescence properties were studied. The X-ray diffraction patterns (XRD) showed that a pure Sr2ZnMoO6 phase phosphor was obtained after sintered at 1 250 ℃. The emission spectrum of the Sr2ZnMoO6:Sm3+ phosphor was characterized, which peaked at 563, 598, 607, 645 nm, corresponding to the 4G5/2→6H5/2, 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions of Sm3+, respectively. The strongest one appears at 645 nm. The excitation spectrum consisted of charge transfer band (284 nm) and characteristic transition (403 nm). The concentration quenching could be observed when x was more than 2%, and it was confirmed that the mechanism of concentration quenching was electric dipole-dipole interaction by Dexter theory. Under the condition of doping charge compensation of Li+, Na+ and K+, the emission intensity of Sr2ZnMoO6:Sm3+ was improved, and it was found that Li+ ions gave the best boost. These Sr2ZnMoO6:Sm3+ phosphors may be potentially used as red phosphors for white light-emitting diodes.关键词：luminescence;phosphor;Sr2ZnMoO6;concentration quenching;charge compensation81|59|3更新时间：2020-08-12
- 摘要：We designed and synthesized two new iridium (Ⅲ) diazine complexes and, where Ph= phenyl, containing 2-(2,4-difluorophenyl)- pyrimidine (DFPPM) as the cyclometalated ligands. OLEDs with iridium(Ⅲ) diazine complexes as phosphor have high-efficiency and long luminance half-life, however, diazine compounds show a significantly redshift of the emission band than pyridine compounds. Therefore, it will be a great challenge to synthesize blue phosphorescent materials with diazine compounds as ligands. The complexes were characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) and their photophysical properties were investigated by UV-Vis spectroscopy and photoluminescence (PL) technique. The PL spectrum of in solution has its maximum emission peak at 472 nm and 489 nm, whereas has its maximum emission peak at 447 nm and 472 nm. The luminescence of shifts to the blue region compared to that of (DFPPM)2Ir(acac), indicating that the HOMO-LUMO gap is increased due to the higher ligand field strength of the phosphine. Compared with, shows a significantly blue-shift of the emission band. The ligand field strength of CN is larger than Cl due to its strong σ donor and π acceptor ability. This causes larger splitting of the d-orbital and consequently more lowering of the metal-centered HOMO. Complex of (DFPPM)2Ir(CN)(PPh3) emits deep blue light with Commission Internationale de l’Eclairage (CIE) coordinates of (0.14, 0.15). Electroluminescence (EL) device was fabricated when the complex of was doped into polymer host polyvinylcarbazole (PVK). Compared to the photoluminescence spectrum, a red-shifted of emission was observed from the electroluminescence spectrum. The reason of red-shift of EL spectra is in progress.关键词：iridium (Ⅲ) diazine complex;organic light-emitting devices;phosphorescent material;blue-light material76|85|1更新时间：2020-08-12
- 摘要：Silicon nitride (SiNx) thin films were deposited by bipolar pulse reactive magnetron sputtering technique with different experiment parameters. Digital microscope and UV-Vis spectroscopy were used to study the surface structure and optics band gaps of the films. Confocal microscopy Raman spectrometer was used to study the Raman spectra of the silicon substrate, the as-deposited films and the annealed films. It is found that the films are Si-rich SiNx films and the most important influence factor on optics band gaps is the flow of nitrogen. The results of the Raman investigation show that the amorphous and crystalline silicon peaks appear in the film. After annealing, the amorphous silicon peaks were weakened or disappeared. It indicates that the crystallization appears in the film apparently. The shift of crystalline silicon peaks shows that silicon nanocrystals appear in the film, and the average size is about 6.6 nm.关键词：SiNx;reactive magnetron sputtering;UV-Vis spectroscopy;raman spectra;optics band gaps150|286|6更新时间：2020-08-12
- 摘要：Eu3+ doped BaO-TiO2-3SiO2 luminescent materials have been synthesized by Sol-gel method, the molar ratio of this fluorescence materials is n(Ba):n(Ti):n(Si):n(Eu)=1:1:3:x. The crystal structure and the luminescent properties of the samples are measured and characterized by using the method of DTA-TG, IR, powder XRD and excitation and emission spectra, respectively. The DTA-TG analysis shows that the weightlessness is obvious in the temperature range of 50~400 ℃, and this phenomenon corresponds to the loss of dissociated water, ethanol and acetic acid. The IR spectra shows that the samples are mostly composed of the Ti—O—Si and O—Si—O bonds. Powder XRD analysis indicates that the samples are non-crystal material. The excitation and emission spectra show that the best annealing temperature is 800 ℃ for preparing material and the optimum Eu3+doping molar ratio is x(Eu)=5.75×10-3. It also shows that the best excitation lights are the ultraviolet light with the wavelength of 395 nm and the visible light with the wavelength of 465 nm when the wavelength of the monitoring light is 612 nm, that is to say, the monochromaticity and the luminescent intensity of red light excited from the samples are optimum and basically the same when the wavelengths of the excitation lights are 395 nm and 465 nm, respectively.关键词：sol-gel method;BaO-TiO2-3SiO2：Eu3+;luminescent materials82|50|2更新时间：2020-08-12
- 摘要：Efficient inverted top-emitting organic light-emitting diode(ITOLED) using a thin Cs2CO3 layer modified Al as the reflective bottom cathode is demonstrated. With tris-(8-hydroxy-quinoline) aluminum (Alq3) as emitting layer and MoO3/Ag as semitransparent anode, the Al/Cs2CO3 based ITOLED shows a tune-on voltage of 3.6 V, luminance efficiency of 9.8 cd/A and 3.4 lm/W, which are much better than those (4.2 V, 8.6 cd/A, 2.85 lm/W) obtained from Mg:Ag based ITOLED and those (5 V, 5.5 cd/A, 1.57 lm/W) obtained from bare Al based ITOLED. Electron-only devices research shows that a stronger electron-injection is obtained from Al/Cs2CO3 than Mg:Ag and Al, which is attributed to the lower work function of Al/Cs2CO3 than Mg:Ag and Al. The good performance of Al/Cs2CO3 based ITOLED is attributed to the efficient electron injection from the Al/Cs2CO3 cathode as well as a microcavity effect.关键词：OLED;Cs2CO3;inverted top-emitting;electron injection105|169|3更新时间：2020-08-12
- 摘要：The carrier transport and recombination in light-emitting diodes (LEDs) determine the non-uniform intensity and distribution of the internal heat source. The non-uniform temperature field also influences the carrier transport and recombination in LEDs. Thus the carrier transport and recombination are strongly coupled with temperatures. In this paper, the internal quantum efficiency, spectrum characteristic and photoelectric conversion efficiency of LEDs with substrates of sapphire, Si and SiC are systematically studied by a non-isothermal multi-physics-field coupling model. It is shown that the LED with SiC substrate has the smallest efficiency droop effect and exhibits the highest spectrum intensity and photoelectric conversion efficiency, among the LEDs with substrates of sapphire, Si and SiC. This is because the LED with the substrate of SiC has the best thermal dissipation capability, thus the non-uniform temperature field has the smallest effect on the carrier transport and recombination, leading to the significantly enhanced carrier concentration in the active region and decreased current leakage.关键词：light-emitting diodes;internal quantum efficiency;substrate;temperature field68|145|0更新时间：2020-08-12
- 摘要：This paper presented a rapid determination method, which was based on the variation of LED lamp transient temperature field and the third boundary condition. It used the surface temperature measured values of LED lamp to calculate its surface convective thermal transfer coefficient. Based on balance theory of convective heat, we designed test equipment that can work under a higher intensity of thermal transfer conditions of the surface. Experimental results show that the test method is simple and practical, the time is short (~30 min), and the accuracy is high (<0.2%) and reliable. It can be used for projects that related to surface thermal convection coefficient measurements.关键词：surface temperature;surface convection thermal transfer coefficient;convection thermal balance;curve fitting;engineering thermal design83|145|0更新时间：2020-08-12
- 摘要：We designed a type of reflector that consisted of one-dimensional diffraction gratings and one-dimensional photonic crystal. It can be used for thin-film silicon solar cells. The structure parameters were optimized by Legendre polynomial expansion method,and the reflectivity at the range of 400~1 200 nm was calculated. Under the high reflectivity one-dimensional photonic crystal, the propagation path of the photon can be extended and absorbed in the battery. The results show that the diffraction grating and a back reflector in the photonic crystal structure are efficient at the range of 750~1 100 nm. Back-reflection layer can greatly improve the light harvesting capacity and enhance the conversion efficiency of solar cells.关键词：photonic crystal;diffraction grating;silicon thin film solar cells;reflectivity98|137|6更新时间：2020-08-12
- 摘要：In order to enhance the temperature stability of 852 nm laser diode, the gain of InGaAlAs, InGaAsP, InGaAs and GaAs quantum-wells were calculated by a comprehensive model theory, and the peak gain and wavelength versus operation temperature for the six different quantum-wells were compared and discussed. The results indicate that In0.15Ga0.74Al0.11As quantum-well is the most appropriate candidate for 852 nm laser diode when the higher gain and better temperature stability demanded simultaneously. Compressive-strained In0.15Ga0.74Al0.11As single quantum-well 852 nm laser diode was grown by metal-organic chemical vapor deposition (MOCVD). The wavelength shift with temperature for 852 nm laser diode is 0.256 nm/K, the experimental results are in good agreement with theoretical calculation results.关键词：lasers;AlGaInAs;quantum-well;numerical simulation143|373|4更新时间：2020-08-12
- 摘要：Three 976 nm diode laser short bars were used as submodule to manufacture high brightness fiber coupled module with CW hundred watts class output power. First, beam transform systems were employed to shape beams emitted from each submodlue; Second, the three beams were stacked in direction of lower beam parameter product by means of spatial multiplexing technology; Finally, the laser was focused into a multimode fiber with 200 μm core diameter and NA=0.22 by optimized lens. Experiment result showed that divergence angle of the focused laser beam was 24.8° and its beam waist diameter was 175.2 μm; laser output from fiber could reach to 107 W, equalizing brightness of 2.23 MW/(cm2·sr), which is a higher level in China. Furthermore, the wall plug efficiency is 43.1% when driving current is 52.5 A, which is far higher than that of solid state laser. Finally the thermal resistance was computed by means of measuring spectrum with different current and the result is 1.29 K/W which indicates favorable heat dissipation of the module. All of the result showed that the module can be used in the field of pumping fiber lasers, medical, material processing and so on.关键词：diode laser short bars;fiber coupling;high brightness;ray tracing76|112|9更新时间：2020-08-12
- 摘要：A software for the numerical simulation of crystalline silicon solar cells is developed. Photocarrier continuity equation, effective mobility, effective minority carrier diffusion length and carrier recombination on crystal boundary of multicrystalline silicon are taken into account in the physical model. The software outputs the numerical simulation of crystalline silicon solar cells by numerical results and graphics. As the simulation results close to experimental data, the software can be a good guide for the design and production of crystalline silicon solar cells.关键词：crystalline silicon solar cells;numerical simulation;Matlab/GUI90|91|0更新时间：2020-08-12
- 摘要：The selective responding of Salen-type fluorescent probe, N,N'-bis(2-hydroxy-1- naphthaldehyde)-l,2-phenylenediimine(NAPPDIH) to Mg2+ was studied. The fluorescence and UV/Vis titration experiments indicated that NAPPDIH bound Mg2+ at the molar ratio of 1:1. With the binding of NAPPDIH to Mg2+, the fluorescence spectra exhibited a specific enhancement, the UV-Vis absorption exhibited a red shift, and a naked eye color varied from pale yellow to deep yellow. The influence of other metal cations on the fluorescent spectra of NAPPDIH was investigated, the results showed that the fluorescence intensity of NAPPDIH could be greatly increased only by Mg2+ ion. Besides, a good linearity between the enhanced fluorescence intensity and the concentration of Mg2+ from 3.0?10-6 mol/L to 5.0?10-5 mol/L was established. NAPPDIH was predicted as a fluorescent probe to rapidly detect Mg2+.关键词：N;N'-bis(2-hydroxy-1-naphthaldehyde)-l;2-phenylenediimine;Mg2+;fluorescence spectra;UV-Vis spectra119|101|0更新时间：2020-08-12
- 摘要：We proposed a detection method for detecting aircraft hydraulic oil leakage——fluorescence method. Taken Mobil phosphate ester hydraulic oil as an example, the experiments verified the feasibility of the fluorescence method in the detection of phosphate ester hydraulic oil leakage. LS-55 fluorescence spectrophotometer and the laboratory build system were used to analyze the fluorescence characteristics of HyJet Ⅴ phosphate ester hydraulic oil, Jet Oil Ⅱ lubricant and 2197 lubricant. The results show that three kinds of oil can be distinguished by different fluorescence emission spectrum peaks, which indicates that it is feasible to detect phosphate ester hydraulic oil leakage with fluorescence method. The technology is of great significance to achieve the real-time,online and on-site measurement of hydraulic oil leakage.关键词：aircraft;fluorescence;leakage;phosphate ester hydraulic oil101|191|2更新时间：2020-08-12
paper
- 摘要：Computational fluid dynamic (CFD) based thermal simulation and transient thermal measurement are utilized to evaluate the thermal performance of OLED in this paper. The effects of input power, panel orientation and air velocity on the thermal characteristics of OLED are investigated and discussed. It is found that obvious thermal gradient exists between junction and substrate or glass cover, and the thermal gradient increases obviously with the input power. The thermal characteristic has a close relationship with the orientation of OLED panel and air velocity.关键词：OLED;junction temperature;thermal resistance122|130|3更新时间：2020-08-12
- 摘要：The temperature characteristic of 1.06 μm InGaAs/InGaAsP quantum well laser diode was studied. The output optical power, threshold current, conversion efficiency and spectra of the module were measured and analyzed when the module was operated with different current at different temperature. The results show that the module’s characteristic changes with the temperature in the range of 15 ℃ to 55 ℃. The module’s CW output optical power reduced from 40.7 W to 29.4 W. The threshold current increased from 9.29 A to 17.24 A. The conversion efficiency reduced from 54.22% to 37.55%. The lasing wavelength shift is 0.37 nm/℃ and the characteristic temperature is 68.6 K. The temperature of the device in the actual application process should be controlled in the range of 15 ℃ to 25 ℃ to maintain the stability of the device performance.关键词：semiconductor laser;1.06 μm;threshold current;temperature characteristic88|169|4更新时间：2020-08-12
- 摘要：The behaviors of ZnO films using t-BuOH and H2O as oxygen precursors were investigated. Despite the fact that both t-BuOH and H2O are of lower activity, the ZnO epilayer has a higher growth rate when t-BuOH is used as oxygen precursor, due to its more effective prevention of the gas phase pre-reaction. Compared with H2O, ZnO epilayer get a better crystal quality by using t-BuOH as oxygen precursor. And the Hall mobility up to 37.0 cm2稸-1穝-1 is achieved in the flim where t-BuOH is used as oxygen precursor. The research shows that t-BuOH is more suitable for oxygen precursor of the MOCVD growth of ZnO epilayer.关键词：ZnO;MOCVD;O precursor;t-BuOH89|46|0更新时间：2020-08-12
Device Fabrication & Physics
- 摘要：The organophosphate pesticides, parathion and methyl-parathion, are studied in this paper. Their ground-state configurations are optimized by the AM1 semi-empirical method of the quantum chemistry. Then, the ground-state configurations are optimized to the excited states configurations by the method of single excited interactions CIS. On this basis, the absorption spectra of their ground-state configurations and the fluorescence spectra of their excited-state are computed on the level of B3LYP/6-31+G(d),using the time dependent density functional theory(TD-DTF). The imaginary frequency does not appear from the vibration analysis of the optimized ground-state configurations. The computed spectra are compared with the spectra from that of the experiments using the English Edinburgh FLS920P spectrometer.The results show that they are coincided and the optimizations above are reasonable.This study provides theoretical support on the pesticide detection.关键词：organophosphate pesticides;molecule configuration;absorption spectra;fluorescence spectra;quantum chemistry93|128|1更新时间：2020-08-12
Spectral Analysis
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