最新刊期
卷 32 ， 期 4 ， 2011
- 摘要：Erbium-doped fiber amplifier (EDFA),utilizing the emission transition 4I13/2→4I15/2 of Er3+, is a key element of the 1.5μm window telecommunication system. In recent year, in order to raise amplifier gain parameters, many solutions, such as Er3+/Yb3+, Er3+/Eu3+, Er3+/Sm3+-doped, were introduced. In this paper, novel Er3+doped and Er3+/Yb3+co-doped TeO2-Bi2O3-SiO2-B2O3 glasses were prepared by high-temperature melt-quenching method. The absorption spectra and emission spectra of Er3+- doped glasses, the emission spectra and lifetimes of Er3+/Yb3+co-doped glasses were measured and investigated. The intensity parameters Ωt (t=2,4,6) were calculated by using the theory of Judd-Ofelt. Under 808nm semiconductor laser excitation, the infrared emission intensity ratio of Yb3+ ions to Er3+ ions and mechanism of counter energy transfer were discussed in Er3+/ Yb3+co-doped glasses. The results indicate that a maximum value of full width half maximum (FWHM) of 1.53μm infrared emission spectra is 90 nm in Er3+-doped glasses, and the suitable content of Yb3+ ions is helpful for decrease disappearing population velocity of Er3+:4I13/2 level, increase emission intensity of Er3+:4I13/2→4I15/2 transition and lifetime of Er3+:4I13/2 level.关键词：counter energy transfer117|12|0更新时间：2020-08-12
- 摘要：We studied the effects of trimethyl–aluminum (TMAl) preflow on the properties of AlN films grown on (0001) sapphire substrates via metalorganic chemical vapor deposition using high-temperature treatments. Short TMAl preflow treatments had little effect on the surface morphology of the AlN films, but hexagonal islands appeared on the surface when the TMAl preflow time was increased. As the preflow time increased, the crystalline quality decreased and the stress state of the AlN films also changed. The origin of this stress behavior can be explained through a combination of extrinsic stress and intrinsic stress.关键词：stress112|12|0更新时间：2020-08-12
- 摘要：Water soluble NaYF4：20%Yb3+，2%Er3+ upconversion nanoparticles were prepared in ionic liquid. The obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and luminescence spectra. The morphology and crystal structure can be well controlled by adjusting the fluoride concentration. Based on the experimental date, the high fluoride concentration was in favor of the formation of hexagonal phase. The products could be dissolved in water and the solution exhibit bright green luminescence pumped with 980-nm laser.关键词：upconversion120|18|0更新时间：2020-08-12
- 摘要：Pr3+-doped 12CaO·7Al2O3 (C12A7 ∶ Pr3+) powders were prepared using the coprecipitation method and were characterized by XRD, excitation and emission spectra, fluorescence lifetime, afterglow decay, thermoluminescence and photostimulated luminescence. The emission peaks at 491,535,614 nm are attributed to the transition of 3P0→3H4, 3P0→3H5 and 1D2→3H4 of Pr3+ ions. The long afterglow emission locate at 491,535,614 nm, the time of the afterglow emission is about 300 s. By fitting the thermoluminescence spectrum data, the depth of the trap is about 0.63 eV. After the samples were irradiated by UV light (230 nm) for 5 min and placed in the dark for 5 min to drain the afterglow,the intensive photostimulated luminescence(PSL)is observed under infrared excitation (808 nm) due to the existence of the shallow traps. Our results indicate that C12A7 ∶ Pr3+ phosphor with three-wavelength phosphorescence and two-wavelength optical storage can be used in optical storage field as one kind of multi-dimension recording materials.关键词：12CaO·7Al2O3;Pr3+ ion;optical storage115|48|2更新时间：2020-08-12
- 摘要：The long-persistent properties of the phosphor SrAl2O4 ∶ Eu2+,Dy3+ (or SAO ∶ ED) have been modulated by doping with Yb3+ or/and Er3+ according to the energy-level model proposed recently by Dorenbos. To analyze the decay process, we use a new developed analytical model instead of the usually adopted empirical one. The decay curves have been analyzed by this model. It is found that the doped Yb3+ does enhance the light-emitting intensity of SAO ∶ ED as predicted by Dorenbos, yet it acts not as a light-emitting center, but as an auxiliary excitation center. In consistent with Dorenbos' prediction, the doped Er3+ does act as a trap center. But when SAO ∶ ED is co-doped with Er3+ and Yb3+, Er3+ plays a role,which exerts an effect of re-trapping, increases the initial light-emitting intensity and reduces the decay time, but the figure of merit of light-emitting does not change significantly.关键词：long-persistent phosphor;decay curve;doping;SrAl2O4116|38|2更新时间：2020-08-12
- 摘要：Eleven rare earth complexes were synthesized with dibenzoylmethane (HDBM),1-phenyl-3-biphenyl -1,3-dione (HPBPD) as the first ligands and 1,10-phenanthroline(phen),dipyrido quinoxaline (dpq),dipyrido- phenazine (dppz) as the second ligands. Their elemental analysis, TG-DTA, UV spectra, IR spectra and fluorescence spectra were measured, the results indicate that the complexes have the compositions of RE(DBM)3L and RE(PBPD)3L·1/2H2O (RE3+= Eu3+,Tb3+;L=phen, dpq, dppz). The molar conductivity shows that all the complexes are non-electrolyte. The data of IR spectra and UV spectra indicate that the azatriphenylenes through the N atoms of the phenanthroline moiety and HDBM, HPBPD through oxygen atoms coordinated with RE3+ ions, respectively. The fluorescence spectra data show that the fluorescence intensity of β-diketone Eu3+ complexes are stronger than the series of complexes of terbium. The abilities of energy transmission of phen and dpq are stronger than dppz. The luminance properties of the rare earth complexes were studied in detail. The triplet state energy of HDBM (20 700 cm-1) is higher than that of Eu3+ 5D0 (17 293 cm-1) and the energy of Tb3+ 5D4 (20 454 cm-1). In all the ternary complexes, Eu (Ⅲ) complexes have strong fluorescence, while the fluorescence intensity of Tb (Ⅲ) complexes is less than that of Eu (Ⅲ) complexes, which is due to the small difference between the triplet energy of HDBM and the lowest excited state energy of Tb3+.Thus it is possible that energy transfer from HDBM ligand to Eu3+ is more effective. As a high UV absorption coefficient for organic ligands, the energy transfer is effectively to the rare earth luminescent center ion, producing a characteristic emission spectrum.关键词：azatriphenylenes;β-diketone;rare earth complexes;fluorescence property130|159|0更新时间：2020-08-12
- 摘要：Novel red-emit phosphors, Na2Ca4(1-x-y)(PO4)2SiO4 ∶ xEu3+ ,yBi3+ were synthesized for WLED by conventional solid-state reaction at 1 200 ℃. Effects of the H3BO3 flux, the re-calcination time and doping concentrations of Eu3+ ,Bi3+ on the luminescence properties were investigated. It was found that a higher Eu3+ emission intensity can be obtained if 30% H3BO3 was added as flux. No apparently structure transformation of the Na2Ca4(PO4)2SiO4 matrix was observed after doping Eu3+ ,Bi3+. The phosphors give the characteristic emission of Eu3+ at 615 nm under the excitation of 395 nm. Samples re-calcined at 1 200 ℃ for 1.5 h gives a strongest emission. The red emission of Eu3+ can be significantly enhanced by co-doping of Bi3+ via an energy transfer process which involves the charge transfer (CT) transition of Eu3+-O2-→Bi3+→Eu3+. The optimized doping mole fractions of Eu3+ and Bi3+ are x=0.04 and y=0.01, respectively. It shows that the Na2Ca4-(PO4)2SiO4 ∶ Eu3+ ,Bi3+ is a promising red phosphor for NUV-chips based WLED.关键词：Na2Ca4(PO4)2SiO4 ∶ Eu3+;Bi3+;solid-state reaction method;white-LED;red-emit phosphor116|39|0更新时间：2020-08-12
- 摘要：The green-emitting phosphors SrCO3 ∶ Mn2+ were successfully synthesized by conventional solid-state reaction combined with co-precipitation method in a carbon-reducing atmosphere. The photoluminescent pro-perties and crystal structure of the samples were investigated by fluorescence spectroscopy and X-ray diffraction, respectively. XRD results showed that the phosphors possess pure trimetric crystal structure. And the PL spectra showed a strong broad-band green color emission located at 500~600 nm (λex=267 nm) correspon-ding to the 4T1(4G) →6A1(6S) transitions of Mn2+ ion in SrCO3 ∶ Mn2+ phosphors. The optimum sintering temperature is about 1 000 ℃ and the best doping concentration is 2.0% in mole fraction. A strong concentration quenching effect is presented at the concentration of x(Mn2+)＞2.0%.关键词：SrCO3 ∶ Mn2+;co-precipitation method;luminescence124|189|0更新时间：2020-08-12
- 摘要：The Y2O3 ∶ Er3+ nanometer phosphors coated with SiO2 was synthesized by the microemulsion method. The X-ray diffraction results showed that the as-prepared powders were cubic phase of Y2O3. The TEM pictures demonstrated that the powders have the nearly spherical and the average diameter of the particles was in the range of 60~80 nm. Under the excitation of 980 nm diode laser, a very strong green emission centered at 562 nm and a red emission centered at 660 nm were observed, which were assigned to the transitions of 4S3/2/2H11/2→4I15/2 and 4F9/2→4I15/2 energy levels of Er3+ ions, respectively. The research on luminescent intensity and the exciting power relations revealed that this up-conversion process was a two-photons absorption process. Because Y2O3 (nucleus)/SiO2 (shell) has highly effective performance on the up-conversion luminescence and was easy to dissolve in the water and united with organic matter and biological member, the application of this nanometer nuclear-shell structure material in the biological fluorescence mark domain is significance.关键词：nanometer phosphors;reverse microemulsion method;up-converting luminescence;nanometer nuclear-shell structure102|54|3更新时间：2020-08-12
- 摘要：The silicon nanoparticle have been grown by radio-frequency plasmas-enhanced chemical vapor deposition technique and the photoluminescence(PL)of the silicon suspension have been studied by both steady-state and time-resolved photoluminescence spectra. The steady-state PL spectra of the silicon suspension show that a blue PL band around 440 nm is found for the as-prepared silicon suspension emits. An increase of the intensity for the blue band around 440 nm followed by a red photoluminescence centered at 750 nm after storing the suspension for two months. The steady-state PL spectra excited by different wavelength and time-resolved PL spectra of the samples demonstrate that the blue PL band with a delaytime of nanosecond order is caused by the band-to-band recombination in Si nanocrystals. The oxidation of the silicon nanoparticle causes the decaytime increasing. The red PL band originates from radiation recombination of carries via defect/surface-related states and the delay-time of which is on the order of microsecond.关键词：silicon nanoparticle;radio-frequency plasmas-enhanced chemical vapor deposition;photoluminescence107|249|0更新时间：2020-08-12
- 摘要：Ti4+doped borosilicate glass has been prepared. The as-made glass was heat-treated and crystallized. X-ray diffraction (XRD), TEM, absorption spectrum and emission spectrum of glass ceramics were measured. Crystallite size of BaYF5 glass ceramics were calculated by Scherrer formula and the comparing with the result of TEM. White emission band (300~800 nm) originated from the charge transferring of Ti4+ (3d0)-O2-(2s2 3p6) can be observed in Ti4+ doped borosilicate glass ceramics. Comparing with the as-made glass, significantly increased luminescence was observed in the glass ceramics. By optimizing the heat treat temperature and concentration of Ti4+, borosilicate glass ceramics with CIE coordinate (0.261,0.351) can be obtained which is close to the standard white-light illumination (0.333, 0.333).关键词：glass-ceramic;Ti ion;X-ray diffraction;phosphors105|66|1更新时间：2020-08-12
- 摘要：The temperature (including annealing temperature and measurement temperature) effects on the structure and optical properties of Eu/TiO2 nanomaterials were studied. It was found that the particle size is increase with the annealing temperatures. The emission intensity of the Eu3+ ions increases with annealing temperature, but decreases when the annealing temperature is over 973 K. Meanwhile, a broad emission band ascribed to defect states associated with Ti3+ ions and oxygen vacancies is intensified with the increasing of annealing temperature. The fluorescence spectra at low measurement temperatures show that the emission intensity of the broad emission band is enhanced while the emission from Eu3+ ions is weaken with the decrease of annealing temperature. The mechanism was discussed in this paper.关键词：temperature;Eu3+;rare earth;TiO284|53|0更新时间：2020-08-12
- 摘要：Nonpolar (112 0) a-plane GaN films with two-step AlN buffer(a low-temperature (LT) and a high-temperature (HT) AlN layers) were grown on (11 02) r-plane sapphire by metalorganic chemical vapor deposition (MOCVD). The as-grown films were investigated by high-resolution X-ray diffraction (XRD) and photoluminescence (PL). The two-step AlN buffer has been proved to be advantageous in crystal quality compared with one-step LT-GaN or HT-AlN buffers in our early works. In this report, the thickness of the two-step buffer was further optimized, and much less anisotropic a-plane GaN films were achieved. It was found that the LT-AlN layer of the two-step buffer played a key role in reduction of anisotropy of the GaN film grown.关键词：GaN;anisotropy;XRD;AlN;buffer layer165|64|7更新时间：2020-08-12
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Efficient Green Phosphorescent Polymer Light-emitting Diodes Based on Cyclometalated Iridium Complex
摘要：A novel iridium complex with sterically bulky camphor-derives group as β-diketonate, i.e., (2-phenylpyridinato-N,C2') irdium(Ⅲ) (3-acetyl-camphor) , was synthesized and it was characterized by 1H NMR, ESI-MS, and elementary analysis. This complex exhibited a higher phototoluminescence quantum efficiency (0.54) than (2-phenylpyridinato-N,C2') irdium(Ⅲ) (acetylacetonate) (0.34) in 2-methyl- tetrahydrofuran solution. Efficient green phosphorescent polymer light-emitting diodes using Ir(ppy)2(acam) as dopants showed high efficiencies and stable EL spectra, with maximum current efficiency of 15.1 cd/A, maximum power efficiency of 4.23 lm/W and maximum brightness of 9 939 cd/m2 at doping mass fraction of 1%.关键词：iridium complex;camphor-derives group;synthesis;phosphorescence;PLEDs.130|262|4更新时间：2020-08-12 - 摘要：A leaf-shaped silicon light-emitting device is designed and fabricated with standard 0.35 μm CMOS dual gate technology. The left-shaped light-emitting device includes three wedge-shaped emitting devices, and the pn junction structure is n well/p+ junction. The device's photograph is measured using the Olympus IC microscope, and the electrical properties of devices were tested. The device operates in avalanche breakdown, and the threshold voltage is 8.8 V, which can emit yellow and visible light. Under forward bias condition, the turn-on voltage of the device is 0.8 V. Comparing with the wedge device, the leaf-shaped device is affected by the series resistance divider, and appears an enhanced luminescence on the tip. After analyzing the results, it is obtained that they are related to the layout of electrode.关键词：silicon LED;standard CMOS technology;layout of electrode96|126|0更新时间：2020-08-12
- 摘要：A method of using electroluminescence (EL) imaging to detect the hidden defects in silicon solar cells under the condition of certain bias is presented in this paper. The EL wavelength of silicon solar cells ranges from 850 nm to 1 200 nm. In the case of forward bias, the EL intensity is related to the concentration and diffusion length of minority carriers, but under the reverse bias, EL regime and illumination intensity are corresponding to defect areas and defect density of battery, respectively. The EL of solar cells can be quickly captured by silicon CCD camera, and the hidden defects of silicon solar cell can be found according to the intensity value of EL imaging. Since the EL intensity of the intrinsic deficient is more sensitive to temperature than that of the extrinsic defect, the types of defect can be checked out by the difference of EL intensity, which responds to the change of temperature.关键词：silicon solar cells;electroluminescence;hidden defect;silicon CCD camera149|145|1更新时间：2020-08-12
- 摘要：The Co-doped ZnO film was grown by electrodeposition method, the carrier concentration is 1017 cm-3, but the sample is paramagnetism. The electrons can not induce the room temperature ferromagnetism, only the introducing of additional carriers can enhance the ferromagnetic exchange action and induce the room temperature ferromagnetism. Nitrogen-doped ZnCoO film was obtained in plasma-enhanced chemical vapor deposition system, where NH3 plasma provided N source. After an ammine plasma treatment the room tempe-rature ferromagnetism was detected on ZnCoO sample. So some holes generated by N doping play an important role for the room temperature ferromagnetic properties in Co doped ZnO sample.In our experiments, although the sample still is n-type semiconductor, there are some holes in the crystal generated by plasma treatment. In this theory, a bound magnetic polarons (BMPs) could be formed after the introduction of p-type dopant N.关键词：post-treatment;ferromagnetism;doping89|85|0更新时间：2020-08-12
- 摘要：Lithium carbonate doped 3,4,9,10-perylenetetracarboxylic dianhydride (Li2CO3 ∶ PTCDA) was fabricated as electron injection layer in NPB/Alq3 heterojunction based organic light emitting diodes (OLEDs). It was found that the current of OLED using Li2CO3 ∶ PTCDA was strongly dependent on the Li2CO3 doping concentration. The OLED using Li2CO3 ∶ PTCDA(1 ∶ 1) with Al as the cathode exhibits an improved power efficiency and significantly increased luminance, comparing with the one using Li2CO3 ∶ BCP(1 ∶ 4) with Al as the cathode and the one using the regular LiF/Al cathode.It is because the electron conductivity for Li2CO3 ∶ PTCDA/(1 ∶ 1) is much higher than that Li2CO3 ∶ BCP(1 ∶ 4) and neat Alq3. In addition, it is found that there exist a Schottky barrier at the intrinsic interface of Alq3 and Li2CO3 ∶ PTCDA(1 ∶ 1), which suppress the electron transfer from Li2CO3 ∶ PTCDA(1 ∶ 1) into Alq3. However, the release of Li atoms upon the Al deposition onto 1 ∶ 1 Li2CO3 ∶ PTCDA could turn the interface into an ohmic contact, thereby delivering efficient electron injection from Li2CO3 ∶ PTCDA(1 ∶ 1) into Alq3. We provided a class of high-function, low-cost, and easily fabricated n-doped material for the performance enhancement of OLEDs.关键词：organic light emitting diodes;n-type doping;PTCDA;BCP166|112|0更新时间：2020-08-12
- 摘要：The silver nanoparticles have been prepared by oxidation and reduction method and their effects on the optical behaviors of riboflavin aqueous solution have been investigated. The absorption intensity of riboflavin was enhanced. After the silver nanoparticles added into the solution, the 372 nm peak was red-shifted and the 444 nm peak was blue-shifted. The fluorescence of riboflavin solution was quenched with the increase of silver nanoparticles concentration. The mechanism of the quenching of riboflavin aqueous solution has been discussed from the enhancement of non-radiative channel,reduction of local field near the surface of silver nano-particles, distribution reduction of riboflavin molecules in the first single excited stated and energy transfer etc.关键词：silver nanoparticles;riboflavin;absorption spectrum;fluorescence quenching;energy transfer101|218|1更新时间：2020-08-12
- 摘要：In order to evaluate the method of UV-B radiation damage on plant cell by photonic technology, soybean callus was radiated by 50 μW/cm2 UV-B for 16 h. Ultraweak photon emission from soybean callus was collected and analyzed. The results showed that strength of spontaneous luminescence (SL) in ultraweak photon emission of soybean callus increased and delayed luminescence (DL) decreased gradually. Through the analyses of dynamic presses of DL, the change rules of dynamic parameters of DL such as integrated inten-sity I(T),initial I0,correlation time τ and decay constant β were obtained. It was indicated that integrated intensity I(T),initial photon number I0, correlation time τ and decay constant β decreased with the UV-B radia- tion time, and I(T) was positive correlation to initial photon number I0. The order parameter used to describe order degree of cell was defined according to biological signification of ultraweak photon emission. The study found that the changes of the order parameter of soybean callus under the action of UV-B radiation reflected the damage of UV-B radiation on cell. So, the damage of UV-B radiation on plant cell could be expressed by the order parameter based on ultraweak photon emission of cell.85|67|0更新时间：2020-08-12
- 摘要：The interaction between Fenbufen and bovine serum albumin(BSA) was studied with fluorescence spectra and UV-visible absorption spectra in the presence of simulating physiological systems.It showed that the complex formated by BSA and Fenbufen lead to the static quenching of the intrinsic fluorescence of BSA. The binding site number n and apparent binding constant KA were measured according to Stern-Volmer equation.The distance between BSA and Fenbufen was obtained based on the Förster nonradiative energy transfer theory. We also confirmed that the main sorts of binding force between Fenbufen and BSA is electrostatic force. Meanwhile, synchronous fluorescence and three-dimensional fluorescence spectra were used to investigate the structure change of BSA before and after the introduction of Fenbufen.Furthermore, the effect of coexistence metal ions on the binding constants of Fenbufen with BSA was also discussed.关键词：fenbufen;bovine serum albumin;interaction;fluorescence spectroscopy;UV spectroscopy92|161|2更新时间：2020-08-12
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