最新刊期
卷 31 ， 期 4 ， 2010
- 摘要：The effect of the electron-phonon interaction on the optical absorptions is theoretically studied for electrons confined in Morse quantum wells. The wave functions and energy levels are described in Morse quantum well by perturbation theory when the electron-phonon interaction is considered, and analytic expression for the optical absorption is obtained by the compact density-matrix method and the iterative procedure. The numerical results for typical GaAs/AlGaAs material show that when considering the electron-phonon interaction the optical absorption coefficients are enhanced, and the total optical absorption is strongly bleached at the linear center. It is obtained that the larger the asymmetry of the quantum wells is, the sharper the peak will be when considering the electron-phonon interaction, and the greater influence of the polaron will be. Furthermore, the correction of electron-phonon interaction effect on the energies of the electron makes the peak shift to the aspect of the high energy.关键词：Morse quantum well;optical absorption coefficient;polaron112|76|2更新时间：2020-08-12
- 摘要：Iron-activated LiAl5O8 is one of red emitting phosphors, exhibiting a broad-band photoluminescence peaked around 675 nm. The component of the matrix and the content of activation ion in LiAl5O8 ∶ Fe3+ phosphors were studied in this paper. The results shown that, under the monitoring at 673 nm, the ordered phase of excitation spectra indicated that there is a strong absorption band at 284 nm, which is charge transfer band of Fe3+-O2-.And there is a single emission band at 673 nm emission under 254 nm excitation. And the emission band is slight asymmetry in the direction of longer wavelength, which belongs to 4T1(4G)→6A1(6S) transition.The luminescent intensity is the strongest when the content ratio of Li2CO3 and Al2O3 is 0.21. The emission intensity enhances as the content of Fe3+ increases. When the content of Fe3+ is 0.5%, the luminescent intensity is the strongest. But the luminescent intensity decreases when the content of Fe3+ increases over 0.5%.关键词：red phosphor;LiAl5O8 ∶ Fe3+;synthesis;photoluminescence102|51|0更新时间：2020-08-12
- 摘要：Electron Raman scattering (ERS) is investigated theoretically in asymmetric triangular double quantum wells (ATDQWs) within the framework of effective-mass approximation. The differential cross-section (DCS) is derived. Numerical calculations are performed for GaAs/AlxGa1-xAs ATDQWs. Results show that the ERS spectrum depends not only on the doping content but also on the asymmetry of ATDQWs. The spectrum yields a red shift with increasing the asymmetry of quantum wells or decreasing the Al doping content.关键词：Raman scattering;double triangular quantum wells;intersubband transition;differential cross-section107|177|0更新时间：2020-08-12
- 摘要：The red phosphor of CaSnO3 ∶ Eu3+ powders were prepared by sol-gel method. During the preparation, PEG (10000) as is the surfactant was added in CaSnO3 ∶ Eu3+phosphor. The influence of PEG(10000) on crystal structure, particle size, morphology and luminescent properties of the phosphor were investigated by means of X-ray diffraction (XRD), laser particle size analyzer, scanning electron microscopy (SEM) and the fluorescence spectrophotometer. The results showed that the structure of CaSnO3 ∶ Eu3+ is not changed by PEG (10000) adding, in the same time the particle size and the morphology were improved by the disperse effect of PEG(10000). And the luminescent intensity of CaSnO3 ∶ Eu3+is enhanced slightly only by adding the PEG(10000).关键词：CaSnO3 ∶ Eu3+;PEG;particle size;luminescence96|52|1更新时间：2020-08-12
- 摘要：Green long persistent phosphors of MgAl2O4 ∶ Mn2+ were synthesized at high temperature under weak reductive atmosphere. The XRD pattern of the sample shown that the product is the simple MgAl2O4 phase. Photoluminescence (PL) excitation and emission, long-lasting phosphorescent (LLP) emission, decay curves, and thermostimulated-luminescence (TSL) spectra were used to characterize the powder phosphor. The sample emits green LLP emission at about 520 nm when excited by 209 nm. There are two ways of excitation energy: (1)Mn2+ ions is excited directly under UV excitation between 279 nm and 451 nm, resulting in green photoluminescence; (2)For 209 nm excitation, Mn2+ ionscharge transfer transition exists, so the electrons from the Mn2+ ground state 6A1 are excited to the conduction band (CB). On one hand, the electrons in the CB can relax to the excited states of Mn2+ through nonradiative processes, and then is green emission followed. On the other hand, some of the electrons in the CB can also be trapped in the electron traps, and then released at high temperature, then turned to the excited states of Mn2+ through nonradiative processes, leading to the phenomenon of green LLP of Mn2+. The possible mechanism for this phenomenon of green LLP of MgAl2O4 ∶ Mn2+ is also investigated based on the experimental results.关键词：long-lasting;trap;MgAl2O4 ∶ Mn2+144|52|1更新时间：2020-08-12
- 摘要：According to the related calculation formula of microcavity device, we use transfer matrix method to simulate and compare with two mirrors which form the resonant cavity of microcavity organic light-emitting device (MOLED). We observed that,as metal mirror's reflectivity increases, electroluminescence (EL) and full wavelength of half maximum (FWHM) of microcavity device become narrow, peak position moves to the designed resonant peak of 520 nm, peak intensity and EL integral intensity increases gradually. The result shows that the bigger the metal mirror's reflectivity is, the better the result is.As the periodicity of DBR mirror increases in 1~9, peaks of EL are all 520 nm, FWHM narrows gradually, integral intensity decreases gradually, peak intensity increases at first then it decreases, and at 4 periodicities it is the biggest. So, when we design MOLED, the periodicity of DBR is an important parameter. It isn't good for light emitting if the reflectivity of DBR is bigger and the effect of microcavity is smaller if the reflectivity is smaller. We must make a resonable choice according to the purpose and need.关键词：organic light emitting device;microcavity;mirror99|116|3更新时间：2020-08-12
- 摘要：The Co doped thin ZnO films were prepared on glass substrates using RF magnetron sputtering method. The influence of O-Ar ratio on the structural, electrical and optical properties of the films have been studied. The films are single phase and have wurtzite structure with c-axis orientation, and have good textures with little nano-crystalline grains and smooth surface when O-Ar ratio is 2 ∶ 8. The concentration of carriers of these films decreases as O-Ar ratio decreases, but as the Hall mobilities increased the Hall resistance is the lowest when O-Ar ratio is 2 ∶ 8. The film deposited at the O-Ar ratio of 2 ∶ 8 shows a highest transmittance and has an emission peak.关键词：thin ZnO ∶ Co film;resistivity;hall mobility;transmittion spectrum;photoluminescent spectrum105|116|0更新时间：2020-08-12
- 摘要：Thin ZnO films were prepared by RF reactive magnetron sputtering with different sputtering pressure and argon-oxygen ratio.The effect of the sputtering pressure and argon-oxygen ratio on the structure and optical properties of the ZnO films were studied using the X-ray diffraction (XRD), scanning electron microscopy (SEM) and F-7100 photoluminescence (PL) spectroscopy. The results indicated that the thin ZnO films have hexagonal wurtzite single phase structure and a preferred orientation with the c axis perpendicular to the substrates.When the sputtering pressure is 0.6 Pa and the argon-oxygen ratio is Ar/O2=20/5.5 sccm, the (002) plane diffraction peak intensity and the grain size are larger, the FWHM of (002) peak is the smallest,UV photoluminescence peak intensity is the strongest.关键词：ZnO films;RF reactive magnetron sputtering;sputtering pressure;argon-oxygen ratio;photoluminescence107|164|2更新时间：2020-08-12
- 摘要：The electronic structures and optical properties of pure and Al-N codoped wurtzite ZnO were calculated using first principle ultrasoft pseudopotential approach of the plane wave based upon the density func-ational theory.Codoped theory showed that, in the ZnO doped system,when the concentration of Al and N equal,Al-N complex formed,N may be fully compensated,but the concentration of N is twice or more times as the concentration of Al,may be the formation of Al-N2,Al-N3,Al-N4 complex,these complexes are likely to reduce the ionization energy of a single N atom.To verify the feasibility of this approach,we chosen 32-atom supercell model to calculated the electronic structure and related parameters of the Al-N codoped wurtzite ZnO,and analysised the mechanism of the increasing of the hole concentration in Al-N codoped p-type ZnO.Firstly,we calculated the binding energy of Al-N complex codoped ZnO and found that Al-N complex can exist in ZnO stably, therefore Al-N codoped ZnO can improve the N solubility of doping. Studies showed that,due to the orbital hybrid between N-2p and Zn-3d,the Fermi level is deeply into the valence band, the top of the valence band shift up and the bottom of the conduction band shift down,resulting in the band gap narrowed.While proper control the ratio of Al and N, the exclusion between the acceptor atoms weakened and the acceptor level was lower after the Al-N complex doped ZnO.So Al-N codoping is an important method to improve the characteristic of p-type ZnO.Besides,in the Al-N codoped ZnO system, the decrease of band gap and the absorption bandedge red-shift will happen after Al-N codoping, experimental phenomena also approve the result.关键词：Al-N codoped;wurtzite ZnO;electronic structures;optical properties107|302|8更新时间：2020-08-12
- 摘要：Spintronics as a fast-developing interdisciplinary field, many novel devices, such as spin-FET and spin-LED, have been proposed. However, spin injection from ferromagnet to semiconductor has a low efficiency. In order to overcome this obstacle, diluted magnetic semiconductors (DMSs) have been proposed to realize the spin injection with high efficiency. In this paper, the spin-polarized tunnel through the ZnSe/ZnMnSe/ZnSe/ZnBeSe/ZnSe/ZnBeSe/ZnSe heterostructures is investigated by use of the transfer matrix and the linear combination of Airy functions. The bias and magnetic fields are both applied along the growth direction. The transmission coefficients as functions of the electron longitudinal energy are calculated, and some resonant peaks are observed. The transmission peaks for both spin-up and spin-down electrons move towards lower energy region with the increase of the applied voltage, which indicates that the bias can enhance the tunneling of electrons. For the spin-up case, the doublet resonance turn to singlet resonance with the increase of the magnetic field. However, the height of transmission peaks varies slightly with the magnetic field for the spin-down case. In our opinion, the reason that electrons with different spin have distinct transmission properties can be attributed to the fact that electrons are supposed by a spin-dependent potential in the DMS layer. Furthermore, we also calculate the spin polarization rate. It can be found that the spin polarization rate oscillates rapidly with the electron longitudinal energy in lower energy region, while converges to 0% in higher energy region. The curves of the rate shift towards lower energy region with the increase of the bias are as same as the transmission coefficient curves. Therefore, the spin-flip of electrons with specific energy can be realized by tuning the bias. External magnetic fields generally lift the spin polarization rate. It can be concluded that our heterostructure can be used as a spin-filter.关键词：diluted magnetic semiconductor;spin-polarized;resonant tunneling100|212|0更新时间：2020-08-12
- 摘要：The electron structures and absorption spectra of aluminum-doped cubic GaN for different aluminum contents (x=0,0.125,0.250,0.375,0.500) are calculated by the first-principles ultra-soft pseudo-potential plane wave approach based upon the density functional theory. It is showed that, for the doped systems, the lattice constants reduce, the band gaps broaden, and the absorption spectra shift to the blue region. Thus, the sun blind region ultraviolet detectors requirements could be met.关键词：blende GaN;first-principles;electron structure;absorption spectrum118|150|0更新时间：2020-08-12
- 摘要：Wide bandgap semiconductor ZnO has been intensively studied for its potential applications in the area of ultraviolet (UV) optoelectronics, such as UV detection and UV Emission. ZnO films are promising for high efficiency UV optoelectronic applications due to its wide direct band gap of 3.37 eV at room temperature and large excitonic binding energy of 60 meV. Naturally, high quality Ohmic and Schottky contacts are necessary for commercial produce of ZnO based optoelectronic and electronic devices, such as ZnO UV photodetector. At present, the structures of ZnO photodetectors almost are metal-semiconductor-metal (MSM) Schottky or Ohmic contact surface structure. It is hard to be used for further ZnO UV detector array and single photon detector, and reflection or shelter effect of electrode can reduce the utilization efficiency of incident light. In this paper, a back-illuminated Au/ZnO/Al Shottky UV photodetector was designed and fabricated. It is a vertical structure device. The rounded Al window electrode as Ohmic contact was fabricated on sapphire at first, then ZnO film was grown on sapphire with Al window electrode by radio frequency magnetron sputtering, at the same time, sapphire in the widow also was used for protected layer. At last, the rounded Au electrode was fabricated on 50 nm Au layer by conventional UV photolithography and wet etching. The objective was to use Au as Schottky contact. The diameters of Al window and Au electrode are 950 μm. On I-V curve of Au/ZnO/Al was measured by an HMS 7707 Hall measurement system (Lakeshore), a clear rectifying effect caused by Au/ZnO Schottky barrier was found. It was showed that we have got well Au/ZnO Schottky contact and ZnO/Al Ohmic contact. The insert light was led-in device from Al window. The peak responsivity wavelength is located at 352 nm, and the cutoff wavelength is 382 nm, UV/visible rejection ratio is only one order of magnitude. Due to the device structure is vertical type, it will be valuable for further ZnO UV detector array and single photo detector study.关键词：UV photodetector;back-illuminated;Au/ZnO/Al vertical structure101|195|3更新时间：2020-08-12
- 摘要：GaN-based MQW light-emitting diode films was transferred to metal substrate from Si(111) substrate by electro-plating and chemical etching. Then, high resolution X-ray diffraction(HRXRD) and photoluminescence(PL) was used to investigate the strain of GaN films in the transfer process. In the study, we designed a series of metal substrates of different structure: (1) Copper substrate, (2)chrome substrate and (3)copper/nickel/copper substrate because of their special thermal and mechanical properties. It was revealed that the tensile strain of GaN films decreases when it is transferred from Si(111) substrate to such three kinds of metal substrates, which is propitious to GaN films. And there is a maximal decrease of tensile strain when GaN films are transferred to chrome substrate. The main layer of electro-plating chrome in the chrome substrate is playing an important role in the sustentation to GaN films. And it was found that, with the thickness increasing of main layer, the strain of GaN films has no change, so the thickness of main layer could be added as more as possible, which can enhance the mechanical properties of chips in the manufacture process.关键词：metal substrate;silicon substrate;GaN;film;strain103|114|4更新时间：2020-08-12
- 摘要：Water soluble NaYF4 ∶ 20%Yb, 0.5%Tm upconversion nanoparticles(UCNPs) were prepared by a facile solvothermal approach using polyvinylpyrrolidone (PVP) as the surfactant. X-ray diffraction(XRD) analyses showed that the UCNPs were pure cubic phase NaYF4 nanocrystals. The size and morphology of the UCNPs were characterized by a scanning electron microscopy(SEM). The SEMimages proved that almost all the UCNPs were nanospheres with the size of ~40 nm. The UCNPs could be well dispersed in water to form a clearly transparent solution which could be kept for at least two days and there was no obvious precipitation. Pumped with 980-nm diode laser, the solution presented bright naked eye-visible violet/blue upconversion luminescence and the upconversion mechanism of the UCNPs was also given in this paper. These results showed that the UCNPs had potential applications in biological field as luminescence labeling probes.关键词：NaYF4;water soluble;nanopartical;rare earth;upconversion116|113|1更新时间：2020-08-12
- 摘要：Mn2+ doped nanometer Zn2SiO4 was synthesized through adding KOH and was coated on the surface of SiO2 by a hydrothermal method. The crystal structure, shape and optical properties of the products were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy spectrum and photoluminescence (PL). Also, the reaction of Zn2SiO4 crystals during the hydrothermal process was discussed based on these data. The XRD patterns showed that Zn2SiO4 was obtained on the surface of SiO2 particles at the reaction temperature of 220 ℃ for different reaction time. SEM results showed that the shape of Zn2SiO4 is hexagonal prism. The amount of Zn2SiO4 coated on the SiO2 is decided on reactive conditions. The photoluminescence measurements indicated there are two photoluminescence spectra. One is green emission with peak wavelength at 522 nm,which excited at 250 nm. The other is blue emission with peak wavelength at 442 nm with a wide excitation band in the ragne of 340 to 410 nm. The former is obviously resulted from Mn2+ ions in the crystal, and the latter is originated from the oxygen vacancies in SiO2 particles.关键词：hydrothermal method;Mn2+ doped Zn2SiO4;SiO2;photoluminescence114|110|0更新时间：2020-08-12
- 摘要：The change of matrix structure can provide different local environment for doped rare earth ions, which offers us an effective way to adjust the luminescence property of active ions. In current paper, the influence of the matrix structure on the luminescence properties of Pr3+ and Eu3+ doped fluoride nanoaprticles has been investigated with laser spectroscopic method. The characters of fluorescence emission from single doped and co-doped nanoparticles have been studied too. It was found that the intensity and the color purity of the fluorescence emission were improved greatly by co-doping another kind of ion to the doped nanoparticles as well as by changing the matrix of the nanoaprticles. The experimental observations were discussed based on the energy level structure of doped ions and the symmetry characteristics of nanocrystals.关键词：fluoride nanoaprticles;rare earth ions;fluorescence radiation;energy level transition124|186|1更新时间：2020-08-12
- 摘要：NaYF4 ∶ Eu3+ nanoparticles/hexagonal prism are successfully prepared by hydrothermal method using trisodium citrate as chelator. The obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and luminescence spectra. The morphology and crystal structure can be well controlled by adjusting the hydrothermal reaction parameters and the molar ratio of Citrate/Ln. The size of NaYF4 ∶ Eu3+ nanoparticles is about 50 nm, and the size of NaYF4 ∶ Eu3+ hexagonal prism is about 1 000 nm×1 500 nm (side length×thickness). The possible formation mechanism of NaYF4 ∶ Eu3+ nanoparticles/hexagonal prism are proposed based on the experimental results. It was found that the morphology of samples is determined by the intrinsic crystal structure and the selective adsorption of citrate. The FT-IR spectra prove the presence of the citrate ligands at the surface of the nanoparticles/hexagonal prism. Therefore, the NaYF4 ∶ Eu3+ nanoparticles can be dispersed in the water. The NaYF4 ∶ Eu3+ samples exhibit strong orange (588 nm) and red (614 nm) emissions under 395 nm excitation, which are assigned to the 5D0→7F2 and 5D0→7F1 transition, respectively. From the intensity ratio of 5D0→7F2 and 5D0→7F1 transitions, it can be concluded that more Eu3+ ions are occupied the sites of inversion centers in the cubic-phase NaYF4 ∶ Eu3+ nanoparticles.关键词：trisodium citrate;nanopantick;NaYF4 ∶ Eu3+;luminescence101|98|2更新时间：2020-08-12
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Luminescent Property of Mg Doped ZnO Nanocrystals Synthesized by Co-precipitation at Low Temperature
摘要：ZnO-based luminescent nanomaterials have attracted comprehensive attention because of their great potential applications in ultraviolet laser devices, LED fabrication and bio-imaging due to their large exciton banding energy (60 meV) and wide bandgap (3.37 eV), low toxicity and high photo-stability. ZnO nanomaterials exhibit two kinds of emission: one is ultraviolet (UV) near-band-edge emission at approximately 380 nm and the other is visible deep-level emission in the range 450~730 nm. Generally, ZnO nanomaterials fabricated at high temperature by PLD, CVD and magnetron sputtering get good crystallization and exhibit near-band-edge emission with negligible visible emission. To get highly luminescent visible light emitting ZnO nanomaterials, mass of visible light emitting defects should be introduced to ZnO crystal. Low temperature fabricating and doping are two kinds of methods to introduce defects into crystals.Because the tetrahedral ionic radius of Mg2+ (0.057 nm) is similar to that of Zn2+ (0.060 nm), wide range solubility of Mg2+ in the zinc blend structure is expected. So, Mg2+ doped ZnO nanomaterials have been studied comprehensively. At high temperature, Mg2+ ions take Zn2+ positions in hexagonal structure and form Zn1-xMg<em>xO alloys, band gap of which can be tuned in 3.3~7.8 eV by verifying Mg2+ content. The alloys have been used widely in ultraviolet lasers and Zn1-xMg<em>xO/ZnO heterojunction optoelectronic devices research. However, at low temperature in liquid, because of low free energy and short ionic radius, Mg2+ ions can facilely enter interstitial positions between lattice planes of wurtzite structured ZnO and form Zn vacancies in the crystal, which should introduce energy levels in band gap of ZnO and make the ZnO nanomaterials emit strong visible light. So, it is of both theoretical and practical meanings to study luminescent property of Mg doped ZnO namomaterials prepared at low temperature.In typical preparation, ZnO colloidal nanocrystals were synthesized at 50 ℃ by dropwise adding 10 mL of tetramethylammonium hydroxide 0.552 mol/L in ethanol(AR) dropwise into 30 mL solution of zinc acetate 0.101 mol/L(C4H6O4Zn·2H2O) (AR) in DMSO(AR) under constant stirring. When doping with Mg2+, we added 10 mL of tetramethylammonium hydroxide 0.552 M into 30 mL solution of zinc acetate and magnesium acetate 0.101 mol/L (C4H6O4Mg·4H2O) (AR) in DMSO.When altering Mg2+ concentration in the colloid, we kept the content of Mg2+ plus Zn2+ to be 0.101 M to guarantee a complete reaction. Solid state nanocrystals were precipitated by adding ethyl acetate into the colloid. The precipitates were then centrifugated at 10 000 r/min for 10 min, washed with ethanol and dried at 80 ℃. The phase structure, morphology and optical properties of the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), transmission electron microscope (TEM), absorption spectra (UV-vis), room temperature photoluminescence (PL) and electron paramagnetic resonance (EPR). The results indicated that Mg2+ ions partially take interstitial positions in ZnO NCs. When activated by 342 nm laser, the Mg doped ZnO NCs emit strong greenish white light with emission peak at about 500 nm. With higher Mg doping content, the NCs become smaller and the luminescence get stronger. Quantum yield of 20% Mg doped ZnO NCs is 22.8%. The partially interstitial doping Mode introduced Zinc vacancies (VZn) and interstitial Mg2+ (IMg) into the doped NCs, which were responsible for the enhanced greenish white light emission. Our findings provide a comprehensive understanding of effects of Mg doping on the microstructure and electronic properties of ZnO prepared at low temperature.关键词：ZnO;co-precipitation;Mg doping;photoluminescence122|190|0更新时间：2020-08-12 - 摘要：Well-aligned ZnO nanorods with different diameters were synthesized on ZnO film coated cover glass substrates and Zn foil via aggregation-driven growth method at ambient pressure. The average diameter of ZnO nanorods increased proportionally with the increase of the time. The presence of the strong (002) diffraction peak in the XRD patterns indicated that the ZnO nanorods exhibited (002) preferred orientation and good crystal quality. HRTEM and SAED results showed that the ZnO nanorods are single-crystal. The nanorods on cover glass grew along the ZnO nanoparticles on ZnO film.关键词：nanorod;array;ZnO;hydrothermal method107|117|0更新时间：2020-08-12
- 摘要：Two new complexes of Eu(Ⅲ) and Tb(Ⅲ) chelated with bis(β-diketone) terephthaloyl-diacetophenone (TDAP) were successfully synthesized. The samples were characterized by the element analysis, infrared spectra, UV-Vis spectra, 1H NMR and fluorescence spectra. The results indicated that their compositions are Eu2(TDAP)3·(H2O)2 and Tb2(TDAP)3·(H2O)6, respectively. Photoluminescence measurement indicated that TDAP is a good indigo emitter under UV radiation. The average triplet state energy of the ligand was obtained by analyzing the phosphorescence spectrum of TDAP. The Eu(Ⅲ) complexes display characteristic metal-centered luminescence, while the ligand emissions are completely quenched. The results indicated that the efficient ligand-to-metal energy transfer (antenna effect) occurs. The characteristic red emission appears due to the 5D0→7Fj transitions of the 4f electrons of the central Eu3+ ions. Tb2(TDAP)3·(H2O)6 has poor fluorescence property, this is because the triplet state energy of the ligand does not match with the lowest excited state energy of Tb3+ ions. The possible energy transfer mechanism was investigated.关键词：Eu(Ⅲ);Tb(Ⅲ);luminescence spectra;energy transfer105|141|0更新时间：2020-08-12
- 摘要：In order to design more effective chemiluminescent systems in aqueous solution, it is essential to get a complete image of the luminescent dynamic process. In this work, taking AMPPD molecule as an example, the photoluminescence of the AMPPD authentic emitter—methyl m-oxybenzoate anion in aqueous solvent was systematically studied. By measuring the steady-state and time-resolved spectra, and 1H NMR signal of the authentic emitter solution, the photoluminescence spectrum of the authentic emitter was successfully extracted out. And the result revealed that the photoluminescence spectrum peak of the authentic emitter is coincided with that of its chemiluminescence spectrum within the error range. These results make the meaning on chemiluminescence dynamics of AMPPD more clear, and further will facilitate the design of more effective chemically initiated electron exchange luminescence (CIEEL) systems.关键词：AMPPD;chemiluminescence;hydrogen-bonding effect185|306|0更新时间：2020-08-12
- 摘要：Eu(DBM)3phen complex were synthesized and introduced into polypropylene (PP), obtaining the composite Eu(DBM)3phen/PP film with smooth surface and transparency. Room-temperature spectroscopy and decay dynamics were performed to explore the luminescence properties of Eu(DBM)3phen and Eu(DBM)3phen/PP film. The results indicated that the Eu(DBM)3phen/PP film displays strong characteristic luminescence and interesting decay lifetime of the Eu3+ ions. Furthermore,the luminescence of Eu-(DBM)3phen/PP film exhibits an improved thermal stability compared with Eu(DBM)3phen.关键词：Eu(DBM)3phen;polypropylene (PP);photoluminescence;composite film116|199|4更新时间：2020-08-12
- 摘要：Based on Monte-Carlo simulation, the current derating characteristics with LED parallel circuit is studied, especially the probability distribution of current derating of a series (2 ≤n≤15) of LED parallel circuit, given the forward voltage drop values of LED after bin agree with Gaussian distribution. The simulation shows that the probability distribution of current derating deviates Gaussian distribution, namely the left and right of the peak point of probability density function is asymmetric, Of which the left side is more sharp than the right side. The probability distribution of current derating is more and more tend to be Gaussian distribution as the quantity of parallel LED increasing. As the probability of occurrence that the current bearing by LED exceeds its rated current increasing, the current derating needed by the parallel circuit increases gradua-lly but the increase rate tends to be reduced. The current derating is about between 20% and 30% when the probability is between 0.01% and 1%. The current derating needed by the parallel circuit increases gradually but the increase rate tends to be reduced as the quantity of LED increasing (n>6). The simulation results can be applied to the LED interconnection array.关键词：Monte-Carlo simulation;LED parallel circuit;current derating;probability107|144|0更新时间：2020-08-12
- 摘要：In order to achieve good stability of field emission as well as high current density, various carbon nanotube-based composites were developed. Here, carbon nanotubes/diamond composites were prepared by microwave sintering method. The carbon nanotubes were dispersed through the composite by thoroughly grin-ding the mixtures. Then, the mixtures were pressed into sheets and sintered by microwave in a microwave plasma chemical vapor deposition system. Morphologies and structural characteristics of composites were cha-racteriozed by scanning electron microscopy. The analytic results demonstrated that the carbon nanotubes are uniformly embedded in composite and formed emission tip. The field emission properties of carbon nanotubes/diamond composite cathodes were also measured in a high vacuum chamber at room temperature using a typical planar diode configuration. The measurement of field emission properties were carried out in a diode structure, wherein the sample acted as the cathode and a stainless-steel cylinder with a diameter of 2.1 mm served as the anode. The distance between the cathode and anode was maintained at 300 μm. The measurement results showed that the field emission of carbon nanotubes/diamond composite is enhanced and the high current density is obtained. A high emission current density value of about 15 V/cm2 is obtained. The results revealed that microwave sintering process is an effective and simple method to synthesize carbon nanotubes/diamond composite.关键词：carbon nanotube;diamond;composite materials;microwave sintering;field emission139|161|3更新时间：2020-08-12
- 摘要：The single mode condition for a rib waveguide with large cross section based on silicon-on-insulator (SOI) is determined through the eigenmode analysis by finite element method (FEM). The mathematic model of waveguide coupler based SOI rib waveguide is established, and the relationships among coupling length, power coupling coefficient, waveguide dimension and separation are calculated and analyzed under the condition of single mode operation. The simulation results indicate that coupling length Lc increases and power coupling coefficient decreases with increasing the waveguide separation for a SOI rib waveguide with W=1 μm and H=2 μm. Furthermore, Coupling length Lc increases with increasing the normalized height (r) of rib waveguide when d＜0.8 μm, but it decreases with increasing r under the condition of d＞0.8 μm. The simulation results provide a guideline for the design and application of SOI-based microring resonator.关键词：integrated optics;microring resonator;single mode condition;waveguide coupler109|187|1更新时间：2020-08-12
- 摘要：Transparent conducting thin indium bismuth oxide (IBO) film was prepared by using a modification-specific reactive thermal co-evaporation method. The room temperature carrier concentrations, resistivities and Hall carrier mobilities of the IBO coating were estimated from Hall effect measurement system. Transmittance spectra were measured with a Shimadzu UV-3101PC spectrophotometer. A field emission scanning electron microscopy (SEM) Hitachi S-4800 and GENE SIS2000 XMS 60S (EDAX Inc.) were used to investigate the morphology and ingredient of the IBO film, respectively. The thin IBO film shows a good optical transmittance in the visible spectra range and a electrical resistivity of 3.143×10-3 Ω·cm corresponding to a carrier density of 3.955×1019 cm-3 and a Hall mobility of 50.21 cm2·V-1·s-1, respectively. Using IBO film as the anode, organic light-emitting diode (OLED) with the structure of Glass/IBO/MoO3/NPB/Alq3/LiF/Al exhibits a high luminance of 30 230 cd/m2 and an EL efficiency of 5.1 cd/A. Our results indicated that IBO is a promising transparent conducting oxide material, and a suitable electrical contact for optoelectronic devices.关键词：transparent conducting oxide;doped;In2O3;Bi2O3;organic light-emitting device128|176|1更新时间：2020-08-12
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