最新刊期
卷 26 ， 期 1 ， 2005
- 摘要：The dispute between molecular and band theory arose from the very beginning of extended study of (organic) electroluminescence. We investigated the layered optimization scheme for inorganic electroluminescence and (obtained)the experience of acceleration ability of SiO2 being greater than 10eV, which is large enough to excite an (electroluminescence) materials. We discovered solid state cathodoluminescence by means of this frame and used the newly discovered solid state cathodoluminescence to study the blue spectral shift when the applied voltage is increased. We found three different kinds of spectra in three consecutive intervals of applied voltage. We found that the field ionization of excitons plays a very important and critical role in this blue shift. The switching on of short wavelength emission (recombination radiation) starts only after the beginning of this field ionization. The exciton emission obeys molecular theory and the recombination obeys energy band theory. Thus their demarcation is the appearance of field ionization of excitons. Since the ionization is changing with electric field continuously, there is a region of (coexistence) of these two processes.关键词：field ionization of exciton;recombination;band theory and molecular theory115|195|6更新时间：2020-08-11
- 摘要：CdSe self-assembled quantum dots (SAQDs) were grown on GaAs(100) by LP-MOCVD under Stranski-Krastanow(S-K) mode. Formation process of CdSe SAQDs below the critical thickness was observed by atomic force microscopy(AFM) images. It revealed that the formation of CdSe SAQDs below the critical thick was due to the effect of surface diffusion and strain release. ZnCdSe SAQDs were grown on GaAs(100) based on the calculated critical thickness by LP-MOCVD under S-K mode. Two kinds of variations in the QDs appeared over time, the Ostwald ripening process and formation process, which is interpreted by theory of crystal growth. ZnSeS QDs were grown on GaAs(100) by LP-MOCVD under V-W mode. With increasing the growth duration, the size of dots becomes larger and the density of the dots decreases, which is explained by virtue of surface free energy.关键词：CdSe quantum dots;ZnCdSe quantum dots;ZnSeS quantum dots;formation of quantum dots128|95|0更新时间：2020-08-11
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Development of Study on Inorganic/Organic Hybrid Luminescent Materials Doped with Rare Earth Complex
摘要：Recently, the developing direction of materials is the functional complementarity and the property optimization.The rare earth complexes have highly luminescent properties and good chromatic purity, but they are unstable and lack the desired mechanical properties to be directly used as luminescent sources. These problems are expected to be solved by doping the complexes into suitable solid matrices. The resulting (inorganic/)organic hybrid luminescent materials combine the respective characteristics of organic and inorganic parts.According to the interactions between the rare earth complexes and the matrices, the hybrid materials include Class Ⅰ(the interactions are weak, typically hydrogen bonds or Van der Waals forces) and Class Ⅱ(the organic ligand is covalently linked to the silica framework).We briefly describe the preparation methods and give a review on the developments for the two classes hybrid luminescent materials. The developing trend for inorganic/organic hybrid materials doped with rare earth complex is also prospected.关键词：rare earth complex;inorganic/organic hybrid;luminescence;sol-gel135|200|4更新时间：2020-08-11 - 摘要：In recent years, the lots of novel effects of the quantum dots systems have attracted more and more physicists. Because of the wide device applications and a lot of new physical effects in such structures, understanding the electronic properties of these systems is of particular importance. Several studies have already been carried out on the interaction of the electrons with longitudinal-optical (LO) phonons in quantum dots. Recently, Mukhopadhyay and Chatterjee investigated the polaronic corrections to the first excited-state energies of an electron in a parabolic quantum dot using a canonical transformation method based on the Lee-Low-Pines-Gross formation. Using the Fock approximation of Matz and Burkey, Lepine and Bruneau discussed the effect of an anisotropic confinement on the ground-state energy of a polaron in a parabolic quantum dot. Li and Zhu investigated the strong-coupling polaron in a parabolic quantum dot by the Landau-Pekar variational treatment. It is shown that both the polaron binding energy and the average number of virtual phonons around the electron decrease with increasing the effective confinement length. The results indicate that the polaronic effects are more pronounced in quantum dots than those in two-dimensional and three-dimensional cases. Taking into (account) the electron-bulk LO-phonon interaction, Kandemir and Altanhan using the Lee-Low-Pines (transformation) to calculate the polaronic effects for an electron confined in a parabolic quantum dot. Zhu and Gu investigated the ground states and self-energy of the weak-coupling polaron in a parabolic quantum dot by using the second order Rayleigh-Schrdinger perturbation theory. However, the properties of the strong-(coupling) polaron in the excited state in parabolic quantum dot has not been studied so far. By using the (variational) method of Pekar type, we have studied both the ground state and the excited state of strong coupling polaron in parabolic quantum dot. The polaron binding energies in both the ground state and the excited state, the average number of virtual phonons around the electron and the resonance frequency of polaron are (calculated.) Their dependence on the electron-LO-phonon coupling constant and the effective confinement strength is depicted. The (results) show that, with the increasing the effective confinement strength, the polaron binding energies in both the ground state and the excited state, the average number of virtual phonons around the electron and the resonance frequency of polaron in parabolic quantum dot are decreased. The average (number) of virtual phonons around the electron will increase with increasing the electron-LO-phonon coupling constant.关键词：quantum dot;strong coupling;polaron126|93|2更新时间：2020-08-11
- 摘要：Recently, with the rapid development of epitaxial techniques such as molecular beam epitaxy MBE and metal-organic chemical vapor deposition MOCVD, more and more quasi-one-dimensional electronic systems have been fabricated. In such quantum well wires, the electron motion along the length of the wire is free, but it is quantized in the two dimensions perpendicular to the wire. These quantum structures present some special physical properties and have been applied to many semiconductor devices, such as high-electron-mobility transistors. In recent year, a great deal of experimental and theoretical interest has been concentrated on the study of the electronic properties of these quasi-one-dimensional semiconductor systems. With the use of variational solutions to the effective mass equations, Dagani and Hipolito have calculated the energy and effective mass in a rectangular quantum wires; Yeung have studied the cyclotron resonance of a magetopo-(laron) in parabolic quantum wire by using the variational-perturbation expansion method. Guo et al. discussed the binding energy of polaron in quantum wires by means of density-matrix treatment. Taking into account the interaction of the electron with optical phonon modes, Chuu et al. have studied the energies of the ground state and the excited state in cylindrical quantum wires using Pekar alternative approach and perturbation-variational method. Zhou and Gu have presented the properties of polaron and magetopolaron in cylindrical quantum wires by using variational solutions and linear combination operators methods. The properties of polaron in rectangular quantum wires and in cylindrical quantum wires have been studied by the present authors and co-workers.Considering the interaction of the electron with optical phonon modes, we investigated effective mass of strong-coupling polaronand the mean number of optical phonon in a parabolic quantum wire by using the Tokuda’s improved linear combination operators, the Lagrange multiplier and the variational method.The numerical results showed that, with the increasing of confinement strength ω0 of quantum wire and the Lagrange multiplier u, effective mass m of polaron and the mean number of optical phonon and vibration frequency λ of polaron will increase.关键词：parabolic quantum wire;polaron;effective mass;mean number of optical phonon108|114|1更新时间：2020-08-11
- 摘要：With the development of several experimental techniques, for instance, metalorganic chemical vapour deposition, molecular beam epitaxy and electron beam lithography combined with reverse mesa etching, there has been of considerable interest in understanding of hydrogenic-impurity states in low-dimensional semi conductor heterostructures such as quantum wells, quantum well wires and quantum dots. In recent years, there has been great interest in investigating quantum dots both theoretically and experimentally. Due to the small structures of QD’s, some physical properties such as optical and electron transport characteristic are quite different from those of the bulk materials. The study of the impurity states in these low dimensional structures is an important aspect to which many theoretical and experimental works based. Recent investigations in the reduced dimensionality show that the impurity binding energy will be enhanced with the deduction of the dimensionality. In recent years, the problem of a bound magnetopolaron in a quantum dot has been extensively studied. Petukhov etal. studied the hopping and giant magnetoresistance of a bound magnetic polaron in magnetic semiconductors and nanostrucrure with the golden rule at effective mass approximation. Charrour etal. presented a systematic study of the ground state binding energy of a hydrogenic impurity in cylindrical quantum dot subjected to an external strong magnetic field and performed calculations within the effectivemass approximation using the variational procedure and considering an infinite confining potential on all surfaces of the system. Liu et al. investigated properties of the bound magnetopolaron in a quantum wires. Bouhassoune et al. studied magnetic field effect on the binding energy of a bound polaron in a quantum well by a variational method. Nguyen et al. analysed magnetic field effects of parabolic confining potentials on the binding energy of hydrogen impurities in quantum dots using a very simple trial function with only one variational parameter. Chen etal.derived ground state properties of the bound magnetopolaron using the linear combination operator and unitary transformation method. Corella etal. calculated the ground state and binding energy for the hydrogen impurity in a spherical quantum dot by using the variational method. Zhou etal. derived energy levels of the bound magnetopolaron by the variational method. Li et al. investigated the influence of magnetic field on the binding energy of a hydrogenic impurity in cubic quantum dots, and so on. In the present paper, by using the linear combination operator and unitary transformation method, properties of the bound magnetopolaron in a parabolic quantum dot are studied for the strong electronLOphonon coupling case. Results show that the vibration frequency of the bound magnetopolaron decreases with the cyclotro resonance frequency, the effective confinement length increasing and it increases with the Coulomb potential increasing. The average number of phonons decreases when the effective confinement length, the cyclotron resonance frequency increased, and it increases when the Coulomb potential enhanced.关键词：parabolic quantum dot;strong coupling;bound magnetopolaron;effective confinement length;average number of virtual phonons105|100|1更新时间：2020-08-11
- 摘要：Heavy-metal fluoride glasses have attracted much attention as host materials due to smaller multi-phonon relaxation rate and high transparence. The optical properties of Pr3+ ion doped in hosts have also been investigated extensively for its potential application on full-color displays, optical data storage and biomedical instruments. Since detailed spectroscopic studies provide information leading to an assessment of the application of Pr3+ ions, it is very urgent to explore the optical properties of different levels of Pr3+ ions in different host materials. The purpose of this paper is to investigate optical characteristics of the 3P0 and 1D2 levels in Pr3+:ZBLAN fluoride glass. Firstly the absorption spectra of Pr3+:ZBLAN with two concentrations (1×10-3 and 5×10-3 in mass fraction were measured by using a spectrophotometer. Then by using time-resolved laser spectroscopy technique, the fluorescence spectra and the lifetimes of the 3P0 and 1D2 excited states of Pr3+ ions were investigated under one-photon resonant excitation by a laser beam from the optical parameter oscillator and amplifier system. Experimental fluorescence intensities of the different emission bands were compared with the calculated radiative rates by the Judd-Ofelt theory in literature which indicating that the phenomenological intensity parameters for the Judd-Ofelt theory obtained for Pr3+:ZBLAN is reliable. Due to the concentration quenching, the fluorescent intensity of the 1×10-3 sample is stronger than that of the 5×10-3 sample. However, the lifetimes of the 3P0 and 1D2 excited states of Pr3+ ions in ZBLAN glass are not influenced by the concentration. For 1×10-3 sample, the measured lifetimes of the 3P0 and 1D2 (levels) are 46 and 322 μs, respectively.关键词：Pr3+：ZBLAN glass;rare earth ions;fluorescence spectra;lifetime96|62|2更新时间：2020-08-11
- 摘要：In the last decades, much attention has been paid to the Er3+ doped glass materials since it is widely known that the transition 4I13/2→4I15/2 of Er3+ can give an emission peaking around 1.5 μm, which matches the IR optical communication window.To our knowledge there are very few of investigations on the dynamics of 1.5μm emission of Er3+. The transfer function theory is introduced to investigate transient fluorescent behavior of the transition 4I13/2→4I15/2 in the Er3+ doped materials under 980 nm-pulsed excitation. A mathematical expression for the temporal emission evolution is given. It is found that after having been excited by 980 nm δ-pulse the luminescence decay of level 4I13/2 obeys double exponential function law, and the variation of population of the level 4I13/2 has two stages: rise-stage and set-stage.关键词：Er3+ doped material;transfer function;transient fluorescent behavior136|77|0更新时间：2020-08-11
- 摘要：Pristine,Si-doped,and Si/Nd-doped yttrium aluminium garnet(YAG) nanoparticles were investigated using XRD,TEM,optical absorption and emission measurement.It was found that the coexistence of Si4+ and Nd3+ increased the solubility of both ions and promoted the formation of YAG phase. Single-phase,nanocrystalline (Si/Nd:YAG) powders were obtained at calcination temperatures as low as 920℃.The optical behaviour of the (Si/Nd:YAG) nanopowders was similar to that of single-crystal Nd:YAG.关键词：YAG;nanopowders;optical properties;dopant159|159|0更新时间：2020-08-11
- 摘要：The plasma display panels PDPs are regarded as a medium of large-format panel display. The performance and lifetime of PDPs are strongly related to the nature of phosphors used in it. The working of PDPs is realized by a conversion of vacuum ultraviolet VUV light to visible light. VUV light has higher energy than that of the ultraviolet (UV) light used as the excitation source of conventional lamp phosphors, therefore, the surface morphology of PDP phosphors suffering from VUV radiation is damaged, and the luminescent performance is decreased with PDPs working time, thus shortening the life of PDPs. This indicates that PDP phosphors should not only have high luminescent efficiency, but also are highly resistant to VUV radiation. Obviously, it is essential to choose an appropriate coating material to resist the VUV radiation.In this work, BaAl12O19:Mn2+ powders were prepared by the conventional solid-reaction method. MgF2 was coated at the surface of BaAl12O19:Mn2+ powders by the emulsion method. Some factors, such as reagent concentration and reaction procedure, were investigated, the optimal coating conditions and technique were obtained. The structure analysis of surface-modified (BaAl12O19:)Mn2+ powders was performed by XRD,TEM, IR measurements. The phosphor screen was prepared also for the aging measurement.The results indicated that MgF2 was successfully coated at the surface of BaAl12O19:Mn2+. The luminescent intensity of surface-modified BaAl12O19:Mn2+ decreased only 1.6% at the starting. After aging for 8 h, the luminescence decay of surface-modified samples was significantly less than that of non-modified samples.关键词：BaAl12O19：Mn2+;phosphor;surface-coating;MgF2110|115|2更新时间：2020-08-11
- 摘要：Eu-doped (Y,Gd)BO3:Eu phosphor with spherical particle morphology, small size, high crystallinity and good photoluminescence (PL)intensity was prepared by co-precipitation method. Ultrafine precursor powders were obtained by controlling the solution concentration of Y3+,Gd3+,Eu3+ and temperature of system, the precursor is amorphous and soft when the system temperature maintain from 50℃ to 70℃.The phosphor particle size is influenced by the solution concentration, and the mean size of the (Y,Gd)BO3:Eu particles decreased from 2.3μm to 0.8μm when the solution concentration changed from 0.2 mol/L to 0.5mol/Land shifted to the larger size with the further increase of the solution concentration. Conventional solid state reaction require higher sintering temperature above 1200℃ for pure (Y,Gd)BO3:Eu phase. However, the co-precipitation allows a significant decrease of sintering temperature and the phosphor sintered at 800℃ have pure orthorborate phase already. The X-ray diffraction peak intensities increased with increasing temperature. The phosphors prepared at different temperature 800, 1000, 1200 and 1300℃ were characterized by X-ray diffraction, SEM, particle size determination and photoluminescence. In addition, the characteristics of the particle were compared with those of a commercial product. Crystallinity,particle size and luminescence intensity are dependent on sintering temperature. The morphology and size of synthesized particles are strongly effected by sintering temperature. The phosphor particles prepared at 1200℃ have the best characteristics,such as completely spherical shape, filled morphology, fine particle size, no-aggregation,and the commercial product prepared by conventional solid state reaction has a irregular shape with aggregation, the particles began to agglomerate and the particle size became larger at an firing temperature of 1300℃. The luminescence intensities of the phosphors increase with the sintering temperature and the brightness of phosphor increase with increasing temperatures due to favorable crystallization and has a maximum values at 1200℃ when excited with UV light. The particles sintered at 1200℃ exhibited better morphology than those of a commercial product.关键词：(Y;Gd)BO3：Eu;co-precipitation method;phosphor;PDP;spherical morphology103|131|4更新时间：2020-08-11
- 摘要：Among the host lattices for luminescent material, orthosilicate and metasilicate compounds had been extensively investigated by many researchers because of their excellent chemistry stability, visible light transparency, and relative easy preparation. For example, Mn-doped Zn2SiO4 phosphor which exhibits the highest emission intensity under VUV ray excitation have been intensely studied to be used for large plasma TV screens and the tricolor fluorescent lamp. In general, the phosphors doped with manganese activators have a long (decay) time according to the spin selection rule. The origin of the rather long decay time lies in the fact that the corresponding transition 4T1g(G)→6A1g(S) is spin forbidden. It is well known that the slow decay lifetime of Mn2+ is a disadvantage for the Mn2+ doped Zn2SiO4 phosphor using as the green phosphor, however, a long (lifetime) is an important requirement for the afterglow phosphor, the long lifetime of Mn2+ make it is feasible to be used as a activator ions in silicate host to create long-lasting phosphorescence. On the other hand, all the phosphors doped with manganese ions found up to now have short long-lasting phosphorescence, it is important to find an excellent silicate phosphor that can be applied to practical application. The aim of this work is to report on the long-lasting properties of Zn2SiO4:1.2%Mn,5%Cd phosphor. XRD analysis results show that the Zn2SiO4:1.2%Mn,5%Cd phosphors synthesized at 1050℃ for 3h are single phase and have no detectable amount of CdSiO3 impurity. This phosphors show long-lasting phosphorescence under 240nm or (260nm) UV light for 3 min, the afterglow light can be seen by naked eye clearly in the dark room even after the excitation source have been removed for about 1 hour. The photoluminescence spectra measurement (revealed) that under excitation of 240 and 260nm radiation the luminescence center of Zn2SiO4:1.2%Mn,5%Cd phosphors do not changed because the emission spectrum have the same peaks position and shape. The bright green emission peaks located at～521nm is due to the 4T1g(G)→6A1g(S) transition of Mn2+ ions.The chromaticity coordinates of this phosphor is x=0.2301, y=0.6915. According to the luminescence decay curves measurement results, the Zn2SiO4:(1.2%Mn,)5%Cd phosphors show higher brightness compared to the Zn2SiO4:1.2%Mn phosphors, we considered that the Cd2+ component in the Zn2SiO4:1.2%Mn,5%Cd phosphor results in the longer decay time because the ionic radius of Cd2+ 0.097nm is relative larger than that of Zn2+ 0.074 nm and the Cd2+ is easy to lost during the high temperature synthesis. By introducing 5%Cd2+component to Zn2SiO4:(1.2%)Mn, some electron traps or crystal defects with appropriate trap depth can be created,and these traps result in the long-lasting phosphorescence.关键词：zinc silicate;long-lasting luminescence;manganese ion;cadmium ion102|95|1更新时间：2020-08-11
- 摘要：High quality GaN is grown by epitaxial lateral overgrowth(ELO) technique on SiO2-patterned GaN “template”.he results from luminescence microscope observation reveal that nucleation happens on the SiO2 mask. After the thickness reaches about 4.5 μm, the coalescence starts. The lateral growth rate is almost the same as the vertical growth rate. Voids are formed on all of the SiO2 mask area. ELO GaN is etched in molten KOH for 13min at 240℃. The threading dislocation density is reduced to almost zero in the area on mask. And the threading dislocation density is still high in the area on windows. It is the order of 108cm-2. Also we found that the qualities in masks area for samples with different window area size are similar and have no relation with window area size. The room temperature photoluminescence PL results indicate that the stress in ELO GaN has been released partially.关键词：GaN;ELO;MOCVD113|83|1更新时间：2020-08-11
- 摘要：Various size ZnO hexagonal microrods have been synthesized onto glass substrates through aqueous growth method with the thermal decomposition of an aqueous solution of equimolar zinc nitrate Zn(NO3)2·(4H2O) and methenamine ((CH2)6N4) by controlling the experimental conditions. The ZnO microrods grow from one center to form radial clusters, which consist of more than 2 pair rods symmetrically grown from the center to both sides, and the rods have a flat top end perpendicularly. When the growth time reached two days, we found that the microrods turned into hollow microtubes with the tube-thickness of tenth of diameter. XRD patterns, SEM images, Raman spectrum have been measured, which revealed all samples were hexa-gonal microrods of ZnO with length of 5～6μm and diameter of 0.8～5μm. The Raman spectrum showed four peaks at 332.2, 377.6, 435.4 and 577.8 cm-1, assigned to the 2E2,A1,E2 and E1(LO)modes, respectively. The growth mechanism is discussed, Zn(NO3)2 dissolves and forms growth units of tetrahedron Zn-(OH)4 under the reaction of the surface activator (CH2)6N4, then the incorporation of growth units leads to the formation of the ZnO crystal lattice at the interface through a dehydration reaction (OH-+OH-H2O+)O2-. The fastest of the growth velocity along [0001] direction leads to the formation of the ZnO microrods. The excitation spectra showed that except the intrinsic inter-band excitation of shorter than 370nm, there was a strong exciton excitation peak located at 387nm with FWHM 30nm at room temperature. The photoluminescent spectra showed that there was a wide orange-red emission with peak at 630 nm and FWHM 250nm when the excitaion wavelength at 387nm. The cathodoluminescent spectra showed a strong orange emission peak at 580nm with FWHM 140nm and a weak UV emission peak at 395nm with FWHM 20nm. Compared with the calculated data of these intrinsic defects by the literature with the theory of FP-LMTO, we attribute the orangered and red emission to the luminescent transition from oxygen vacancies to the valence band.关键词：ZnO;microrod;luminescence;aqueous growth method with thermal decomposition107|77|2更新时间：2020-08-11
- 摘要：Crystallization of organic thin films is one of the main degradation mechanisms of organic light emitting diodes (OLEDs). The induced crystallization of N,N′-di(naphthalene-1-yl) N,N′-diphenyl-benzidine (NPB) thin films by copper phthalocyanine (CuPc) buffer layer with different thickness and nucleus sizes was studied by atomic force microscopy (AFM) and wide angle X-ray diffraction (WAXRD). It was found that the NPB with CuPc as buffer layer crystallized more easily than that without CuPc buffer layer, and CuPc films can induce the crystallization of NPB films. These results may provide evidence that the long-term degradation of an OLED with CuPc as buffer layer can be partially attributed to the crystallization of the hole-transporting layer NPB induced by CuPc.关键词：organic thin films;crystallization;AFM;degradation;OLED126|153|0更新时间：2020-08-11
- 摘要：It is very important to obtain data of energy band structure for optimizing and choosing organic electroluminescent materials. There are mainly four methods can be used such as UV-Vis absorption spectroscopy, quantum chemistry calculation, the photoemission analysis and cyclic voltammetry to obtain the band gap, HOMO and LUMO energy level respectively. Because the energy level can be determined easily by the electrochemical method, the cyclic voltammetry is widely applied. In the present work, a series of carbazole deri-(vatives) have been studied. The experimental values of HOMO energy level have been gained through the onset potential in the cyclic voltammetric curves. The experimental results showed that the HOMO energy level of N-methylcarbazole is 5.99 eV which is lower than those of other N-alkylcarbazole derivatives for the σ-π hyperconjugation between methyl and carbazyl. The electron-withdrawing carbonyl on the compound ethyl N-carbazylacetate(6) makes it have lower level of the HOMO (energy) level than carbazole. The HOMO energy level of CBP is the lowest for the conjugation of aryl which reduces the density of electron cloud on the nitrogen atom dramatically. It is informed that the HOMO energy level is significantly influenced by the characteristics of the substituent. The electron-donating group can improve the ability of hole transfer of carbazole derivatives, but the electron-withdrawing group is just contrary. The carbazole derivatives with conjugated aryl have relative low HOMO energy level and can be used as hole barrier materials. The experimental conclusions are constructive to direct the design and synthesis of organic electroluminescent materials.关键词：organic electroluminescent materials;HOMO energy level;cyclic voltammetry122|240|4更新时间：2020-08-11
- 摘要：PM (Passive Matrix) driver demands high quality PLEDs (Polymer Light Emitting Diodes). Each pixel should have perfect diode characteristic, with rectification ratio over 104, or else the application of such new type of display will be hampered by crosstalk. For diminishing D.Braun’s crosstalk[1], PM driver must break off the relation between selected pixels and idle pixels when driving selected pixels, so reverse voltage (VDD-VEE) is necessary to apply to idle rows and (columns) when row was scaned, thus AC-PM driver is formed. However, it was found that the leakage of a pixel can cause PLED screen to produce two sorts of crosstalks, and the leaking pixel has no diode characteristic, but has low reverse resistance. During idle time of row scan, the leaking pixel shorts VDD and VEE in IC, produces considerable leaking current which forms abnormal voltage drop on resistance net distributing in display screen and driver IC, thus previous voltage on idle rows and columns is changed, and bias status of idle pixels on them is changed to forward bias, leading to (emission) and forming new type of crosstalk. Such typical crosstalk is expressed two lighting lines: one is column crosstalk, caused by high voltage on ITO anode instead of low VEE, which represents brightness distributing relevant to ITO resistance and metal line resistance; another is row crosstalk, caused by low voltage on metal cathode instead of high VDD, accompanying with selected pixels in eyes. Based on experiment test and phenomenon inspection, discusses that the coincidence reason of row crosstalk and column crosstalk from the low rectification ratio pixel, depicts its influenced rules in the form of miniature. Finally obtains vital consequence resulting in circuit which can be probed, and submits the possibility of lessen the crosstalk, especially the idea from IC re-designing aspects which can relieve crosstalk occurred in products.关键词：passive matrix;row crosstalk;column corsstalk;OELD135|93|0更新时间：2020-08-11
- 摘要：The development of field emission display (FED) has been the subject of (increasing) scientific (interest) due to their extensive application in flat panel display and microelectronics area. The cathode(electron-emitter) material is one of the key factors for FED. So far, many kinds of emitters were discovered, such as metal emitters (Spindle-type field emitters), silicon emitters, diamond film emitters, diamond-like carbon (DLC) film (emitters) and carbon nanotube emitters. But it is intricate for most of the emitters in producing process and difficult to be fabricated in large area. However, some polymers, which are quite cheap, easy to synthesize, soluble in organic solvents to make high quality films in large area by using convenient methods, were created in making the emitters. Pure polymer emitters were demonstrated by Musa, and further work was done in our group. The great difference between our work and Musa’s is that we used conducting polymers while Musa used insulated polymers. What is more, Musa’s paper only gives the field emission I-V curve, the light emission image had not been showed. We believe that the conducting polymers have high conductivity, which is expected to bring about a low turn-on emission field, high emitting current density, and better picture quality. In our experiment, the conducting polymers, CSA-doped polyaniline (PANI-CSA), was made on a cleaned 1cm×1cm ITO substrate by spin-coating method and then dried on a heater. A display prototype has been fabricated using ZnO:Zn phosphor-coated ITO as an anode. The prototype of our FED device was placed into a vacuum chamber for field emission testing. The relationship between the emission current and the voltage fits the Fowler-Nordheim equation, and the enhancing factor β calculated based on our I-V data is 430. The emission current stability was tested for 50 min. No obvious decrease of the current was observed. By way of studying the surface appearance of conducting polymer after field emission, we analyze the emission mechanism and consider the sunken and protrude shapes produced from initial planar surface by applied high fields playing an important role in increasing the enhancing factor.关键词：conducting polymer;PANI-CSA;films;field emission93|65|1更新时间：2020-08-11
- 摘要：Heat dissipation model of stacks oxygen-free copper microchannel heat sink was established in this paper. Structural parameters of microchannel heat sink were optimized through theoretical calculations and approximate analysis. Minimum thermal impedance of microchannel heat sink Rthm=4.205×10-3 K·cm2/W can be obtained when t=200μm,ωc=60μm,ωf=100μm,p=2.2×106Pa. A new kind of five layers oxygen-free copper microchannel heat sink was designed for high power semiconductor laser stacks according to optimized results and influence of hydraulic pressure drop induced by tropism of microchannel. We fabricated the oxygen-free copper microchannel heat sink based on practical technology. The drop of water pressure of 2.02×106 Pa is not easy to realize in practice. Thermal impedance of 4.982×10-3 K·cm2/W can fit the need of high power semiconductor laser stacks under the actual drop of operation water pressure.关键词：microchannel heat sink;heat dissipation model;structural parameters;hydraulic pressure drop172|257|0更新时间：2020-08-11
- 摘要：High-power laser diode arrays are difficult to use directly in such fields as military, industry, and medicine because of their extremely asymmetric divergent beams (θx≈5～10°and θy≈20°～35°), i.e., their poor beam quality. In order to improve the beam quality of laser diode arrays, special optical systems have to be used to reshape the asymmetric divergent beams. One most simple and effective beam-reshaping way is to change linearly arranged laser beams of the one-dimension laser diode array (LD Bar) into circularly arranged laser beams by fiber arrays. With flat-end fiber arrays, the coupling efficiency is usually about 20%, which is obviously too low to use in most situations. So, fiber arrays with special ends have to be prepared to obtain both high coupling efficiency and high beam quality output of LD Bar. By ray tracing method, theoretically studied that the coupling properties of three kinds of specially prepared fiber arrays with LD Bar were theoritically studied. The results show that, compared with the sphereend fiber and the tapered fiber, the sphere-end tapered fiber having much higher coupling efficiency (over 90%) with LD Bar was optimized. Moreover, when the sphere-end tapered fiber array is in use, output beams of LD Bar with much higher quality can be obtained due to the strong suppression of divergent angles. The sphere-end tapered fibers are easily prepared in experiment by methods of high-temperature melting and chemical erosion.关键词：laser diode array;fiber array;beam reshaping119|77|2更新时间：2020-08-11
- 摘要：The basic principles that a related organic substance can emit fluorescence as it is excited by ultraviolet rays is described, the relationships of molecular structures of organic substances and generation of fluorescence are studied, molecular structures and chemical characteristics of a few common pesticides such as carbaryl, carbofuran, carbisoprocarb and acetamiprid are analyzed and their mechanism of generation of fluorescence is revealed. Moreover, the fluorescence spectrum experiments are conducted by means of a steady-state fluorescent spectrograph with the solutions of carbaryl,carbofuran and acetamiprid using pure methanol, the mixture of 80% of water and 20% of methanol and the alkalescent mixtures (pH=13) as solvents respectively and that their fluorescence spectrograms have been obtained and the relationships of their own molecular structures and characteristics of fluorescence are analyzed. The results indicate that some pesticides, for example carbaryl,carbofuran and acetamiprid, who have groups with plane rigidity structures or conjugate system like aryl ring and heterocyclic ring, can emit fluorescence as they are excited in a certain solvent or under the condition of acid or alkalescence, and they can be analyzed and measured directly or indirectly by fluorescence analysis. Study on fluorescence characteristics of pesticides provides a feasible theoretic basis for further researching and developing a fluorescence spectrometer for pesticides.关键词：fluorescence;pesticides;molecular structures;fluorescence spectrum experiments143|212|4更新时间：2020-08-11
- 摘要：In recent years, natural antioxidants that were used to substitute synthesized antioxidants become trends of international and domestic researches. Aromatic plants have been widely paid attention due to their (ability) of antioxidation. In the present study the nonvolatile parts of dry leaves from large sweet basil and (meyer) lemon (below called basil and lemon) were taken as experiment material. Six chemilum inescence systems and two colorimetric systems were used to evaluate their capacity of antioxidation and that of preventing DNA damage caused by ·OH. The experiments revealed that basil and lemon could not only directly scavenge O(·)2, but also inhibit the bioactivity of xanthine oxidase and then reduce the production of O(·)2. Experiments (also) showed that basil and lemon could efficiently scavenge ·OH,H2O2,ONOO· and DPPH·.Moreover, lemon has a better ability to scavenge H2O2,ONOO· and DPPH· than that of basil. Basil and lemon could effectively inhibit lipid peroxidation and they could obviously inhibit and delay DNA damage caused by ·OH, acting as mixing-type antioxidants. Above results indicate that basil and lemon are very effective antioxidants and free-radical scavengers. Meanwhile famous antioxidant baicalin is taken as a comparison. Baicalin is better in the capacity of antioxidation than basil and lemon in most of the system, but baicalin was purer and the (extraction) process is more complex and needs more cost than basil and lemon. So it is very significant to research on the exploitation and application of basil and lemon. These experiments provide new data for their further exploitation and establish theoretic base for the function study of basil and lemon on food, hygiene and medicine.关键词：large sweet basil;meyer lemon;active oxygen species;active nitrogen species;DNA damage;antioxidant99|75|1更新时间：2020-08-11
- 摘要：The solid powder fluorescence of oil cuttings was studied and we drawn a conclusion that in the range of certain oil concentration, the fluorescence intensity of the solid powder is linear with oil concentration in the powder of cuttings, with a regression coefficient of 0.993 6. But when the heavy oil concentration in the sample reaches a certain degree, the fluorescence intensity does not vary with oil concentration in the powder of cuttings, but its value does not equal zero. At the same time, the fluorescence quenching phenomena of oil cuttings were studied and the high concentration of heavy oil is the primary factor of the fluorescence quenching, which will causes non-linear relation between the fluorescence intensity and oil concentration in the powder of cuttings and results in false analytical data and error characters of spectra. From the study on the mechanism of concentration quenching of fluorescence, we obtained that the concentration quenching is mainly induced by the organic molecular interaction, such as formation of excimer and dimmer, intercrossing relaxation, etc. A comparison was made between the concentration quenching of solid powder fluorescence and the concentration quenching in solution. This showed that (1) when oil concentration of sample reaches a certain degree, the intensity of fluorescence keeps a constant in solid powder, but it equals zero in solution. (2) fluorescence peak of heavy oil locates at shorter wavelength in solid powder than that in solution. (3) the fluorescence quantum yield of heavy oil is larger in solid powder than that in solution. The study is important to develop a new analytical technique of quantitative fluorescence detector which can be applied to the analysis of solid samples with pretreatment, and is significance for quantitative fluo-rescence logging and organic geochemistry.关键词：oil cutting;solid powder fluorescence;concentration quenching105|93|6更新时间：2020-08-11
- 摘要：ZnO has been studied extensively for several applications, such as surface-acoustic-wave devices, ultraviolet light-emitting devices, laser diodes and gas sensors. Apart from these, high quality ZnO films are promising for UV photodetector application due to their wide and direct band gap and large photoresponse. Compared with photoconductive detector, Schottky type photodetectors are more attractive due to their high speed and low noise performance. Previously reported Schottky barrier UV sensitive photodiodes exhibited low quantum efficiency due to a large amount of recombination centers in the polycrystalline ZnO layers. In this paper, hexagonal microtube ZnO was firstly grown on single crystal p-Si(111) substrates by hydrothermal method. The Ag film electrodes was deposited on ZnO by planar magnetron sputtering, therefore Ag/n-ZnO UV photodetector was fabricated. The characteristic of dark- and photo-current of Ag/n-ZnO Schottky UV photodetector, the UV photoresponse and the quantum efficiency of the detector were also investigated. The results of testing indicate that there is a good Schottky behavior between Ag and microtube ZnO, and an effective barrier height is 0.35 eV. Dark current was very small,without illumination. Under illumination using monochromatic light with a wavelength of 365 nm, photogenerated current arrived at 25.6 and 57.9 μA, at a bias of 5 V and 9 V,respectively. A evident wide-range spectral responsivity and higher quantum efficiency of (Ag/n-ZnO) detector were observed. The maximum photo-responsibility of 0.161 A/W and the quantum efficiency of (54.7%) were obtained at wavelength of 366 nm. Therefore, the hexagonal microtube ZnO is suitable to apply for UV photodetector.关键词：hexagonal microtube ZnO;Schottky barrier;UV photodetector;I-V characteristic;spectral (responsivity;) quantum efficiency135|106|5更新时间：2020-08-11
- 摘要：GaP1-xNx alloys (or heavily doped nitrogen in GaP) are usually referred as abnormal alloy due to their giant band gap effect. Recently many attentions have been paid to the study on their photoelectric properties. In this paper, the radiative decay and time-resolved spectra were employed to investigate the transient photoluminescence of GaP1-xNx alloys with x=0.05%～3.1% at low temperature. For the low N concentration (x=0.05%～0.81%) samples with emission of different NNi lines and their sidebands, the (lifetime) is about 30～100 ns in accord with the decay time of NN4, NN3 and NN1 center. For the samples with N concentration up to 1.3%～3.1%, the photoluminescence shows a broaden band and their radiative recombination exhibit the typical exponential decay with 56～36ns, much longer than that of the free excitons (usually about several nanoseconds), but shorter than that of the samples of GaP1-xNx with x=0.43%～0.81%, whose photoluminescence composed mostly of NN4 and its sidebands. And it has a trend that, compared to the NNi bound excitons, the radiative decay time of the alloys decrease with increasing the N composition. However the lifetime only decrease to the same level of that of the NN4 center (about 30ns) which indicates that the newly nitrogen impurity band of GaP1-xNx alloy with x～3% has kept the indirect property of bound excitons with long lifetime, although many PL properties suggested that it has direct band gap. At the same time, due to the longer lifetime for the carriers at the lower energy, the decay time at different detected energies showed that, the higher the detected energy, the shorter the lifetime. In addition to the luminescence decay, the time-resolved photoluminescence were detected. For the high nitrogen concentration samples (GaPN alloys), the energy peak shifts to the lower energy side with the time delay due to the shorter lifetime at higher energy side. For the low nitrogen concentration samples, especially for x=(0.05%) and 0.12%, the relative intensity of deep exciton becomes stronger with the time delay, which is obvious that the energy transfers from shallow center to deep centers e.g. from NN4 to NN3 and NN1. In previous reports, the energy transfer between different NNi excitons was studied by rather indirect method, such as thermal quenching. It is the first time to observe the energy transfer directly between excitons bound to NNi.关键词：GaPN alloy;time-resolved spectra;energy transfer106|103|0更新时间：2020-08-11
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