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摘要：Since Tang and VanSlyke developed an efficient organic light-emitting diode (OLED) based on an organic bilayer structure in 1987, the efficiency has been increased, particularly, the use of n- and p-doped organic transport materials with small-molecule OLEDs leads to improving conductivities and significantly better injection of charge carriers into the OLED. Further concepts have been established such as the insertion of additional organic layers as exciton and charge carrier blockers which can localize the emission zone and prevent exciton quenching effects as well as charge carrier imbalance. In spite of rapid advances in the organic electroluminescent device (OELD), there have still been many hurdles to be overcome for manufacturing a high-resolution full color display. The development of a stable, efficient, and saturated red device remains an important goal for OLEDs which is obtained by using a discrete emitting layer or doping fluorescent and phosphorescent dyes into a host layer. In this report,a organic red electroluminescent device was fabricated based on hole transporting material PVK doped with Ir(piq)₂(acac) by the spin-coating method and vacuum evaporate plating technology. The structure of the device is ITO/CuPc/PVK ∶ Ir(piq)₂(acac)/BCP/Alq₃/LiF/Al. The effect of the doping ratio on the performance of the device was investigated. The device has high perfor-mance when the doping ratio is 1 ∶ 0.08 in mass that the CIE coordinate is located at (x=0.66,y=0.33) and the main emission peak is at 625 nm. The full width at half maximum of the spectrum is only 55 nm. It is attributed to the structure of micro-cavity which is improved by the reasonable thickness of films. The color of a dye can be modified by inserting it into a microcavity. Indeed, a microcavity is formed within a OLED by weak reflections from interfaces. The spectrum of the device has fine monochromaticity that the color purity is 98.2%. The luminescence performance of the device is well improved.  

摘要：We designed and made two devices, one is microcavity organic light-emitting device (MOLED), and the other is non-microcavity device (OLED). The structures of MOLED is G/DBR/ITO/NPB (46 nm)/DPVBi (20 nm)/Alq₃ (56 nm)/LiF (1 nm)/Al (150 nm); OLED is G/ITO/NPB (46 nm)/DPVBi(20 nm)/Alq₃ (56 nm)/LiF (1nm)/Al (150 nm). The performances of MOLED and OLED were tested and analyzed. The OLEDs electroluminescent (EL)-angle curve, at 30 mA/cm² and changing the angle from 0° to 70°, is a broad spectrum. It is the characteristic spectrum of DPVBi luminescence layer, which peaked at 452 nm, the full width at half maximum (FWHM) is 70 nm. The color coordinates (CIE) are (x=0.18, y=0.19). It was proved that OLED has no angle dependence.The MOLED EL-angle curve at the same current of 30 mA/cm² is a narrow spectrum. We can see that, along with the detecting angle changing from 0° to 70°, the EL peak values decreases from 472 nm to 428 nm, namely blue shift. The peak intensity also decreased. The FWHM became larger from 14 nm to 120 nm. The CIE coordinates change from (x=0.14, y=0.10) to (y=0.19, 0.25), the color changes into blue-white from purple-orchid. All of the above proved that the MOLED obviously has angle dependence. The angle dependence of MOLED is disadvantage for flat display application, thus we need reduce it. But this characteristics is virtue and necessary for organic microcavity laser.  

摘要：Y_0.795-xGd_xYb_0.2Tm_0.005F₃ nanocrystals were synthesized through a hydrothermal method. After annealing in the air conditions, the upconversion (UC) emission properties under a 980 nm continuous wave semiconductor laser diode excitation were studied. The experimental results suggested that the violet and ultraviolet (UV) UC emission enhancement were observed in Y_0.795-xGd_xYb_0.2Tm_0.005F₃ nanocrystals, as well as the UC emissions from ⁶D_9/2, ⁶I_J, ⁶P_5/2, and ⁶P_7/2 states to the ground state ⁸S_7/2 of Gd³⁺ were shown, too. The luminescent kinetic analysis implied that, under 980 nm excitation, Yb³⁺ can transfer energy to populate the ³P₂ level of Tm³⁺, make UV, violet, and blue UC emissions obtained, further, the ⁶I_J multiplets of Gd³⁺ were populated through the energy transfer process ³P₂ → ³H₆ (Tm³⁺):⁸S_7/2 → ⁶I_J (Gd³⁺). At the same time, the energy transfer processes occurred between Gd³⁺ and Yb³⁺ or Tm³⁺ based on the energy matching conditions, leading to the above mentioned UV UC emissions of Gd³⁺.  

摘要：The Er³⁺/Tm³⁺-codoped tellurite glasses were prepared by high-temperature melting. The absorption spectra, fluorescence spectra, upconversion emission, and the fluorescence lifetime of samples were investigated under 980 nm LD excitation. Spectral properties of the samples with different concentration of Er³⁺-Tm³⁺ ions were analyzed, the 1.53 μm fluorescence intensity of Er³⁺ reduces with increasing Tm³⁺-ions concentration, but the 1.8 mm emission of Tm³⁺ increases. The Tm³⁺-³H₆→³F₄ absorption cross-section and Er³⁺-⁴I_13/2→⁴I_15/2 emission cross-section were calculated based on Dexter theory, the energy transfer process from Er³⁺-⁴I_13/2 level to Tm³⁺-³F₄ level can occur. The measured lifetimes of Er³⁺-⁴I_13/2 level was decreased from 2.05 ms to 0.8 ms with increasing the mol fraction of Tm₂O₃ from 0.1% to 0.5% where Er₂O₃ mol fraction is fixed at 0.5%, while the energy transfer rate, at first, from Er³⁺ to Tm³⁺ increases rapidly and then tardily does. The upconversion luminescence of Er³⁺ and Er³⁺/Tm³⁺ ions doped tellurite glasses was investigated. The green light of 530 nm and 545 nm, and the red light of 657 nm can be observed in Er³⁺ doped tellurite glass, moreover the 545 nm light intensity is stronger than the 530 nm light. But the green upconversion emission intensity decreases with Tm³⁺-ions doping, otherwise the red upconversion emission intensity increases firstly and then decreases with increasing Tm³⁺-ions concentration. In addition, the intensity of red light is strongest when the Tm³⁺/Er³⁺ concentration ratio is 1/5 approximately.  

摘要：Over the several passed decades, the upconversion luminescence of rare earths doped glasses has been attracted much interest due to its applications in short wavelength laser devices, three dimensional displays and optical storage sources. Therefore, exploring novel materials with high luminescent efficiency and good chemical and mechanical stability has become a challenge to the researchers. It has been of technical and applied importance to understand the mechanisms of the upconversion luminescence in the inorganic materials doped by rare earths. In this paper, a novel oxyfluoride glass sample PGETYA was prepared by a melt-quenching technique. This glass system not only has the higher up-conversion luminescence efficiency, but also avoids the drawback of both the oxide and fluoride host materials. The PGETYA sample consists of 58.52PbF₂-34.43GeO₂-3Al₂O₃-0.05Tm₂O₃-4Yb₂O₃ (in molar), among which GeO₂ is the main component, namely glass former, others are introduced as adjustors to improve the glass performance. Tm³⁺ and Yb³⁺ ions are doped as co-operative luminescent activators. The upconversion emission spectrum was measured under 980 nm excitation by using a semiconductor laser diode. Very strong blue upconversion emission at 476 nm originating from ¹G₄→³H₆ transition of Tm³⁺ can be seen by naked eyes. Meanwhile two weaker red emissions originating from ¹G₄→³H₄ and ³F₃→³H₆ transitions of Tm³⁺ were also observed. Upconversion luminescence intensity variations with the increase of excitation density viz the increase of LD working currents were investigated. The nonlinear curve fittings of the relationship between the up-conversion emission intensity and LD working current to the theoretical result were carried out, and it was concluded that the blue up-conversion for this material is nicely fitting in with the three-photon process and red one fulfills the two-photon process. These results suggested that the studied oxyfluoride glass with the designed composition may be a good candidate material for the practical applications in short wavelength laser and three dimensional displays.  

摘要：Sr₃SiO₅ : Eu²⁺ phosphors were synthesized by high temperature solid state reaction. The starting materials are the analytic reagents SrCO₃, SiO₂, Eu₂O₃. After the individual materials were mixed in the requisite proportions sufficiently, the powders were calcined at 1 300 ℃ for 6 h under the ambience of 5% H₂ in N₂ to reduce Eu³⁺ to Eu²⁺. The structure was checked by powder X-ray diffraction (XRD, D/max-rA, Cu Kα, 40 kV, 100 mA). The excitation and emission spectra are measured by a Shimadzu RF-540 fluorescence spectrophotometer. All the photoluminescence properties of the phosphors were measured at room temperature. The obtained products are Sr₃SiO₅ : Eu²⁺ phosphors. Effect of Eu²⁺ concentration and co-doping activation on the luminescence characteristics of Sr₃SiO₅ : Eu²⁺ phosphors was investigated. The results showed that the emission intensities of Sr₃SiO₅ : Eu²⁺ phosphors firstly increase with increasing Eu²⁺ concentration, and then decrease because of concentration quenching. They reach a maximum at 1% Eu²⁺, and the concentration self-quenching mechanism is the d-d interaction according to the Dexter theory. Moreover, the emission intensities can be enhanced by co-doping rare earth ions, such as Tm³⁺ and Yb³⁺. The relative spectra of InGaN-based Sr_2.98-Eu_0.01Tm_0.01SiO₅, Sr_2.98Eu_0.01Yb_0.01SiO₅ or YAG ∶ Ce phosphors were measured. Because Sr₃SiO₅ : Eu²⁺ phosphor has longer emission wavelength than YAG : Ce, so the color rendering property of InGaN-based Sr_2.98-Eu_0.01Tm_0.01SiO₅ or Sr_2.98Eu_0.01Yb_0.01SiO₅ is better than that of InGaN-based YAG : Ce. In conclusions, Sr₃SiO₅ : Eu²⁺ phosphor is a promising yellow phosphor for white LED manufacture.  

摘要：The samples of YVO₄·xTiO₂ : Eu³⁺ (x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9) were synthesized by the conventional solid state reaction. The structure of prepared sample was measured by X-ray diffraction(XRD) at room temperature. XRD measurements confirmed that the prepared YVO₄ ·xTiO₂ : Eu³⁺ is consisted of two phases. One phase is YVO₄ with the tetragonal according to JCPDS-Card (42-0413), the other phase is Y₂Ti₂O₇ with the cubic pyrochlore according to JCPDS-Card (17-0341). Spectroscopic properties of the sample were studied under the UV/VUV excitation. The effects of Ti doping on the luminescent properties of the sample were investigated and it was found that reasonable Ti doping can highlight the absorption of matrix in UV/VUV rang. The emission spectrum is dominated by the red peaks at 616 nm and 619 nm due to the electric dipole transition ⁵D₀→⁷F₂ of Eu³⁺. It indicated that Eu³⁺ occupies a site lacking inversion symmetry. There is one band peaked at 155 nm in the excitation spectrum of the sample, it could be assigned to the absorption of the host.  

摘要：The phosphor of (La,Ce,Tb)BO₃ was synthesized by high temperature solid state reaction. X-ray diffraction(XRD) patterns indicated that (La,Ce,Tb)BO₃ and LaBO₃ have the same crystal structure, the crystal structure was not changed by doping with Ce³⁺ and Tb³⁺ . Emission scanning electron microscopy (SEM) image showed that the phosphor particles is uniform, the morphology is regular, and the granularity is about 5 μm. The luminescence properties of (La,Ce,Tb)BO₃ phosphor were studied, both the Tb³⁺ characteristic emission and excitation peaks and the Ce³⁺ characteristic emission and excitation peaks were observed in the emission and excitation spectrum of (La,Ce,Tb)BO₃. The emission spectra of Ce³⁺ in (La,Ce)BO₃ and the excitation spectra of Tb³⁺ in (La,Tb)BO₃ have large superposition at 330~400 nm regions, which supply good conditions for energy transfer from Ce³⁺ to Tb³⁺. The energy transfer between Ce³⁺ and Tb³⁺ is primarily as resonance transfer. Both of (La,Ce,Tb)BO₃ phosphor and commercial phosphor (La,Ce,Tb)-PO₄ have main emission peak at 541 nm. Comparing (La,Ce,Tb)BO₃ phosphor with commercial phosphor (La,Ce,Tb)BO₃, (La,Ce,Tb)BO₃ phosphor has a little red shift at 489 nm and its relative emission intensity was 94.7% of the commereial phosphor (La,Ce,Tb)PO₄. Therefore, it is expected that (La,Ce,Tb)BO₃ phosphor would be a promising green-emitting phosphors.  

摘要：The red phosphors of Ca₉R(VO₄)₇ : Eu³⁺(R=Y, La, Gd) were prepared by high temperature solid state reaction method. The structures of these powders were recorded by X-ray powder diffraction. The excitation and emission spectra were recorded by F-4500 spectrofluorometer. The photoluminescence properties were investigated in this paper. The excitation spectrum of Ca₉Y(VO₄)₇ : Eu³⁺ shows two broad absorption bands in the range of 200~350 nm with maximum centered at 254 nm and 320 nm, respectively. The former corresponds to CTS of VO^3-₄ complex and the latter corresponds to an overlap of both CTS of VO^3-₄ complex ion and Eu-O CTS band, and also displays sharp absorption lines of f-f transition of Eu³⁺ ion located at 398 nm (⁷F₀→⁵L₆), 467 nm (⁷F₀→^5D_2), and 538 nm (⁷F₀→⁵D₁), respectively. The excitation spectrum of Ca₉La- (VO₄)₇ : Eu³⁺ is similar to that of Ca₉Y(VO₄)₇ : Eu³⁺. In Ca₉Gd(VO₄)₇ : Eu³⁺, the excitation spectrum also shows two broad bands centered at 274 nm and 331 nm, respectively,which mainly corresponds to the CTS of VO^3-₄ complex ion. The photoluminescence spectra of Ca₉Y(VO₄)₇ : Eu³⁺ and Ca₉La(VO₄)₇ : Eu³⁺ exhibit broad emission of VO^3-₄ complex ion and some sharp lines due to the transition of ⁵D_J(J=0,1)→ ⁷F_J (J=1, 2, 3, 4) in Eu³⁺ ion. With increasing concentration of Eu³⁺ ions, the emission of VO^3-₄ is decreased compared to the transition of ⁵D_J→⁷F_J (J=1, 2, 3, 4) in Eu³⁺ ion. However, the emission of VO^3-₄ is not exhibited in Ca₉Gd- (VO₄)₇ : Eu³⁺. Only the transitions of ⁵D_J→⁷F_J (J=1, 2, 3, 4) of Eu³⁺ ion are observed in this compound. The intensity of luminescence is observed much stronger than that of Ca₉Y(VO₄)₇ : Eu³⁺ and Ca₉La(VO₄)₇ : Eu³⁺ because two kinds of energy transfer processes of Gd³⁺ → VO^3-₄ → Eu³⁺ and Gd³⁺ → Eu³⁺ are occurred. Thus, it was resulted that the luminescence efficiency of Ca₉Gd(VO₄)₇ : Eu³⁺ is improved significantly.  

摘要：The reduction of Eu³⁺ to Eu²⁺ in air was observed in silver ion conducting glasses prepared by melt-quenching technique. White light emission is realized by controlling the sliver concentration, which changes the ratio of Eu³⁺/Eu²⁺. The typical white light emission is shown at the sample, where the concentration proportion of B₂O₃ and Ag₂O is equal to 7 : 3, whose chromaticity coordinates are(x=0.31, y=0.36), color temperatures is 5 000 K. The mechanism of Ag₂O leading to the reduction of Eu³⁺ to Eu²⁺ in air was discussed. A possible explanation can be ascribed to the influence of sliver nanoparticle, which would be formed when the glass melts are poured into pre-heated brass molds and annealed. Since sliver atom is unstable and its outer electron would be transferred to Eu³⁺ ions and makes Eu³⁺ reduce to Eu²⁺. This hypothesis is based upon our previous work. We synthesized borate glass containing sliver nanoparticle by annealing at 500 ℃, which shows yellow body colors. However, we found that yellow is translated into colorlessness after aging for 3 months. By measuring the absorption spectra we can confirm sliver nanoparticle is oxidated into sliver ions because sliver nanoparticle has an absorption peak at 400 nm coming from silver particles surface plasmon. The redshift reason of the emission peak position of Eu²⁺ with increasing Ag₂O content is attributed to two different locations of Eu²⁺ ions coming from BO₃ and BO₄ groups. As Ag₂O concentration increases BO₄ keeps increasing, accordingly, the excitation band at 430 nm shifts toward red. It is believed that Eu-doped silver ion conducting glasses would be potentially useful as an ultraviolet-convertible phosphor for white light-emitting diodes.  

摘要：The principle of activating the phosphors to luminescence by β particle emitted from tritium isotope was introduced. Because the average free path of β-particle is only 4.3 mm, the diameter of the lamp is limited between 4 mm and 8 mm. From experiment, we can come to the conclusions as follows:First, Y₂O₂S : Eu is the familiar phosphors which can emit red ray. Secondly, ZnS : Cu,Al is the familiar phosphors which can emit green ray. Finally, ZnS : Ag is the familiar phosphor which can emit blue ray. From testing, the optimal granularities of Y₂O₂S : Eu, ZnS : Cu,Al, ZnS : Ag are 4.6,5.3 and 5.4 μm, respectively. The methods of phosphor coating and the technics of charging the tritium are introduced in detail. The brightness of the tritium lamp was also tested. At last, the methods of using and storage of tritium lamp were explained.  

摘要：In the article, effect of different particle sizes of YAG : Ce³⁺ phosphor on LED brightness and its reasons were studied. The results showed that the larger the particle sizes is, the higher the brightness is, which is attributed to the integrity of crystal lattice of the phosphor particle. The settling rate of YAG : Ce³⁺ particles in silica was calculated in detail and analyzed deeply, indicating that the larger particle sizes make the settling velocity to be faster, and also the more difficult dispensing in packaging. Taking into account of the comprehensive consideration of particle size and brightness, we concluded that the particle size should not be too large or too small in order to obtain white LED with more brightness, and the distribution range of the particle size should be narrow as much as possible, 10~20 μm distribution may be the best.  

摘要：In_0.82Ga_0.18As was grown by low-pressure metal organic chemical vapor deposition (LP-MOCVD) on InP substrates with two-step growth technique. Effect of buffer layer growth temperature on structural and electrical properties of In_0.82Ga_0.18As was analyzed, which was characterized by scanning electron microscopy (SEM), Raman scattering and Hall measurement. The results showed that the properties of epilayers have close relation to the buffer layer growth temperature and the optimum buffer layer growth temperature was about 450 ℃.  

摘要：Investigation on the origin and relative factors of ultraviolet luminescence (UVL) by photoluminescence and Hall measurements for the Mg-doped Al_xGa_1-xN/GaN superlattice with varying annealing temperature and excitation intensity is presented. The intensity of UVL increases to the maximum and then decreases sharply and the peak exhibites a redshift when the annealing temperature increased in the N₂ atmosphere; at the same activating condition, the hole concentration of the sample and the intensity of UVL decreases and the peak shifts to the lower energy as the Mg content increases. The results indicated that the transition between the shallow donors (V_NH) that is easily disassembled by heat and shallow acceptors (Mg_Ga) caused UVL, which also competes with the transition between deep donors (Mg_GaV_N) and shallow acceptors (Mg_Ga) due to the effect of self-compensation by redshift. The blueshift of UVL is about 260 meV with increasing the excitation density. Studying by the model of band structure of superlattice on the effect of polarization, it was suggested that UVL arises from the change of the transition between V_NH and Mg_Ga in a sawtooth-like band structure due to polarization effect. According to the early reports, the origin of UVL in Mg-doped GaN is still unclear. In this report, UVL is found in Mg-doped Al_xGa_1-xN/GaN superlattice and the difference from Mg-doped GaN is observed through the photoluminescence due to the strong polarization effect in superlattice. This study will help us to disclose the process of the radiative transition especially caused by defects in superlattice clearly and understand the origin of ultraviolet luminescence in these Mg-doped GaN-based materials further.  

摘要：The In_xGa_1-xN/In_yGa_1-yN multiple quantum well structures were grown on sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The quantum efficiency, multi-emission peaks effects and peak-shift information were observed by temperature dependent photoluminescence (PL) spectra, selective excitation PL spectra and PL excitation spectra. The temperature dependent PL spectra showed that the intensity of the main emission peaks decreased only by a factor of 1.36 and peak position has a blue-shift when temperature increases in 30~300 K. Selective excitation PL spectra showed that every peak appeared in PL spectra is separate. The PLE result shows a small Stokes shift for GaN and barrier layer while it is larger for the well layers. A fitting method was also suggested to obtain several absorption edges simultaneously.  

摘要：Using the first-principles ultra-soft pseudo-potential approach of the plane wave based upon the density function theory, we studied the electronic structure and optical absorption of the Si-doped wurtzite AlN system. The obtained results showed that the impurity energy levels are located near the bottom of the conduction band of the host AlN, together with the Al 3p levels make the complex conduction band bottom, and a Mott phase transition takes place. With Si doping, a new absorption peak appears at about 2.02 eV, and thus the absorption property in the visible light range can be improved.  

摘要：The films of ZnO/SiC/Si and ZnO/Si were grown by pulsed-laser-deposition (PLD) technique and were processed to fabricate ultraviolet (UV) detectors. The effects of SiC buffer layer on the structure and photoelectrical properties of ZnO films grown on Si (111) substrates were investigated by the X-ray diffraction (XRD), photoluminescence (PL), current-voltage (I-V) and photoelectrical response measurements. The results showed that the SiC buffer layer can effectively improve the crystalline qualities, optical and photoelectrical properties of the ZnO thin film grown on Si substrate. It is obvious that, as a compliant substrate, SiC buffer layer makes the interface defects and interface state density reduce because the partial stress induced by large crystal lattice mismatch and thermal mismatch between ZnO and SiC can be relaxed.  

摘要：Quantum dots (QDs) samples studied in the experiment were grown by molecular-beam epitaxy on a semi-insulating GaAs substrate. It consists of an InAs QD layer embedded in the middle of a 1λ GaAs cavity. The GaAs cavity is sandwiched between a 2-period GaAs/Al_0.9Ga_0.1As distributed Bragg reflector (DBR) on top and a 20-period GaAs/Al_0.9Ga_0.1As DBR on bottom. The QD layer was formed by depositing 2.35 monolayers (ML) InAs at a growth rate of 0.001 ML/s. The sample has an ultralow density of the QDs. Therefore, we can isolate single QDs without the use of the nanoscaled masks or mesas. In the experiment the sample was cooled to 5 K and a Ti ∶ sapphire laser operating at 750 nm was used as an excitation source. The scanning confocal microscopy with an objective (NA: 0.5) was used to spatially resolve single QDs. The photoluminescence (PL) and time-resolved PL measurements were carried out by time-correlated single-photon counting setup. The excitation light is a right circular polarization light. The polarization PL and time-resolved PL emissions were analyzed by a λ/4 and λ/2 wave plate and a linear polarizer to distinguish different polarization components. All the experiments were performed at low excitation power, which ensures the luminescence working in the single photon emission mode. The main conclusions were given:(1)Both PL peaks of the circular and linear polarization are not shifted and split and the corresponding circular (linear) polarization degree is 30% (4%).In this case, the fine-structure splitting (FSS) is close to zero and the corresponding exciton eigenstates are degenerate circular polarization states.(2)Both PL peaks of linear polarization components (π_x and π_y emissions) are splitting with the FSS of tens or hundreds of eV. In this case, the corresponding exciton eigenstates are two linear polarization states. (3)Depending on the exciton-exciton scattering, the exciton radiative recombination is modified, i.e., when there is a biexciton the decay time of the exciton decreases, compared to the case of only exciton existence at lower excitation power.  

摘要：Adopting improved metal-organic "Green method", colloidal ZnSe, ZnS quantum dots (QDs) were prepared using cheap and low toxic zinc oxide (ZnO) in an organic solvent system of 1-hexadecylamine (HDA), lauric acid (LA) and tri-n-octylphosphine (TOP). The effects of solvents ratio, reaction temperature and growth time on the QD size and photoluminescence properties of ZnSe and ZnS QDs were studied. The results showed that ZnSe and ZnS QDs exhibit the wurtzite structure, good uniformity, dispersity and fluorescent characteristics. The average diameters are in the range of 4.5~8 nm. Choosing the optimal parameters, n(ZnO) : n(HDA) : n(LA)=1 : 2.1 : 5.2, c_TOPSe=1 mol/L, ZnSe QDs with large distributioin range of the size were obtained under the condition of nucleation at 280 ℃ and growth at 240 ℃. With increasing the growth time, the QD size become larger and the emission peak obviously shifts to red.  

摘要：The influence of structure parameters on the performance of GaN Schottky barrier (n^--GaN /n⁺-GaN)ultraviolet photodetectors was investigated. The simulation results indicated that the performance can be improved by increasing the Schottky barrier height and decreasing the surface recombination velocity, thus, the quantum efficiency could be enhanced and the dark current could be rapidly reduced. It was also found that the quantum efficiency can be increased by increasing the thickness or the carrier concentration of n^--GaN layer, however, the dark current can be reduced by decreasing the thickness of n^--GaN layer. A good design of GaN Schottky barrier ultraviolet photodetector is proposed. Especially for the fabrication of GaN Schottky barrier ultraviolet photodetector with high quantum efficiency and low dark current, the Schottky barrier should be higher than 0.8 eV, the thickness of n^--GaN layer should be larger than 200 nm, the carrier concentration of n^--GaN layer should be around 1×10¹⁷ cm^-3, and the surface recombination velocity should be lower than 1×10⁷ cm/s.  

摘要：In nanomaterials science, a great deal of effort has been devoted to the semiconductor nanomate-rials. Research on Ⅱ-Ⅵ semiconductor materials has become a hotspot nowadays, especially in their optical and electric properties. As a kind of luminescent materials, Mn-doped ZnS nanocrystal has drown considerable interests because of its broad potential application prospect, and the luminescent mechanism, preparation method and practical application have been researched deeply. However, the surface states usually act as luminescence quenching centers, causing low luminescent efficiency. There is a large distance for Mn-doped ZnS nanocrystal to application, which is mainly caused by the surface states. Hence, the modification of surface is of crucial importance for the applications of this type of luminescent semiconductor nanomaterials. Among all the surface modification methods, core/shell structure is proved to be a very effective method. In this paper, Mn-doped ZnS nanoparticles synthesized by solvothermal method were successfully coated with CdS shells of various thicknesses by precipitation reaction. The samples were characterized by X-ray diffraction(XRD), transmission electron microscopy images (TEM), X-ray photoelectron spectroscopy (XPS) and the room temperature photoluminescence (PL) spectra. TEM images showed that the nanoparticles are spheric and the average diameter is about 14~18 nm. It was found from the XRD results that the growth of CdS shell is affected by the ZnS : Mn core, resulting in poor crystallinity. The formation of CdS shells on the surface of ZnS : Mn nanoparticles is confirmed by XRD and XPS measurements. As the CdS shell thickened, the Mn emission intensity of ZnS : Mn/CdS nanoparticles shows a gradual decline in the PL spectra.  

摘要：The effect of mechanical milling on the photoluminescence behavior of γ-Al₂O₃ nanopowder was studied. Two emission peaks centered at 343 and 378 nm and a broad emission band ranging between 400~600 nm were observed.It was found that the intensity of the two emission peaks decreases with ball-milling time, while that of the broad band emission remains invarriable. These results suggested that the two peaks are resulted from the surface defects that analogs of F⁺ centers, while the broad band is resulted from impurity.  

摘要：In this work, we developed a simple method for synthesizing CdSe/ZnSe/ZnS multishell quantum dots (QDs). CdSe/ZnSe core/shell QDs was synthesizd using one step injection of zinc precursor into the crude solution of the CdSe reaction system and then CdSe/ZnSe/ZnS core/shell/shell QDs were obtained by epitaxially growing a ZnS shell on the CdSe/ZnSe surface. Introducing a middle shell (ZnSe) sandwiched between CdSe core and ZnS outer shell allows considerably reduce strain inside nanocrystals because ZnSe have the lattice parameter intermediate to those of CdSe and ZnS. In comparison with the method reported previously, our synthesis method effectively simplifies the experimental operation, shortens the experimental period and reduces the waste of the chemcals. The annealing process was used to improve the fluorescence quantum yield of the QDs after the shell growth. The resulting CdSe/ZnSe/ZnS multishell QDs was further characterized in detail. Transmission electron microscopy indicated that the QDs are spherical and the shell is successfully coated on the surface of the CdSe QDs. The size of CdSe core is 2.8 nm, and the size of the CdSe cores with CdSe/ZnSe and CdSe/ZnSe/ZnS shells are determined to be 4 and 5 nm, respectively. The X-ray powder diffraction patterns suggested that the core (CdSe) and shell (ZnSe and ZnS) of the CdSe/ZnSe/ZnS QDs have a pure cubic phase. The luminescence properties of the QDs were investigated by means of photoluminescence and ultraviolet-visible absorption spectra. The results indicated the CdSe/ZnSe/ZnS QDs exhibit a high photoluminescence quantum yield. Besides, it can be seen that the absorption and photoluminescence bands shift to the red during the shell growth due to the large extension of the electronic wave function into the shell material. For the potential biological application, the CdSe/ZnSe/ZnS QDs were transferred into water phase from an organic phase by surface ligand exchange with mercaptopropionic acid. The water-soluble QDs with a quantum yield of about 17% have compatible functional chemical groups.  

摘要：A novel europium(Ⅲ) complex was synthesized using TTA (α-thenoyltrifluoroacetone) as the first ligand and H₂bpdc (2,2'-bipyridine-3,3'-dicarboxylate) as the second ligand. Elemental analysis, thermal analysis, IR and UV-Vis spectrum analysis and fluorescence spectra of the europium(Ⅲ) complex were carried out. Fluorescence properties of the complex in ethanol-aqueous solution were studied, which indicated that the europium(Ⅲ) complex exhibits a strongly characteristic red luminescence of Eu³⁺. The Eu³⁺ emission is very sensitive to pH value, so the complex can be used as pH-dependent fluorescence probe in biomedicine and food detection.  

摘要：It is well known that blue-emitting materials are so important to organic light-emitting diodes for the purpose of full color display. However, up to now, excellent blue-emitting materials have been underdeve-loped and lacked variousness. In this report, we developed a new kind of material which can emit highly efficient blue light, with 2-(2- pyridine)benzimidazole as the ligand, and using representative main elements Mg, Ca and transition metal Zn, Cd as central ion. Highly luminescent complexes are successfully synthesized and excellent blue-emitting complexes are realized. They all display strongly blue emissions and high luminescence quantum efficiencies. The emission peak located at the deep blue region of 400~455 nm, with high photoluminescence quantum yields of 0.31~0.74. In addition, all the blue-emitting complexes with melting points of no less than 250 ℃ own high thermal stability. All these data suggested that these blue-emitting complexes are promising materials in the field of organic light emitting diodes. In order to get a further understan-ding on the factors that dominate the blue luminescence complexes, chemical means are used to adjust their emission peak position. Compared with neutral and ionic complexes, we came to a conclusion that the emissions are assigned to intraligand transitions of the deprotonated ligand. On the other hand, even though the metal ions do not participate the luminescence process, the metal ions in the complexes do play a key role in stabilizing the deprotonated ligand and promoting the luminescence. Considering the promising properties of these blue-emitting complexes, including their high PL efficiency, thermal stability and the blue PL spectra, it was believed that these complexes may find potential applications in the field of organic light-emitting diodes, and corresponding efforts are now being preceded.  

摘要：5-sulfosalicylic acid was modified by the amidation reaction by a crosslinking molecule (3-amino- propyl)trimethoxysilane. The modified functional ligand further behaves as a bridge both coordinates to terbium ion and occurs by in-situ sol-gel process with tetraethoxysilane, resulting in a novel hybrid material. Ultraviolet absorption and nuclear magnetic resonance were applied to characterize the obtained hybrid mate-rial. Fluorescence spectra showed the strong luminescence of terbium ion in the complex.  

摘要：Based on Mie scattering theory, the theoretical analysis and numerical calculation on LiNbO₃ microsphere particles light scattering characteristics were researched. The relationships between scattering intensity and scattering angle,polarization and scattering angle,scattering intensity and size parameter were obtained. The result showed that the forward scattering is dominated, and increases with increasing the radius of particle.The scattering cross section and absorbability cross section have the maximum value when particles radius is approximately 0.1 μm for LiNbO₃ nanoparticle.  

摘要：The globe-like diamond microcrystalline aggregates were fabricated by microwave plasma chemical vapor deposition (MPCVD) method. The ceramic with a Ti mental layer was used as substrate. The fabricated diamond was evaluated by Raman scattering spectroscopy, X-ray diffraction (XRD) spectrum, scanning electron microscope (SEM). The results led to the conclusion that the obtained film consists of crystalline diamonds structures.The field emission properties were measured by using a diode structure in vacuum. A phosphor-coated indium tin oxide (ITO) anode was used for observing and characterizing the field emission. The field emission characteristics of the fabricated diamond was studied under low electric field ( <3 V/μm) and high electric field ( <5 V/μm), respectively. The Fowler-Nordheim (F-N) plots corresponding to the curves of the low electric field and the steady operation circles in the high electric field are almost straight line, which indicated that the mechanism of the electron emission from the diamond microcrystalline aggregate is linked to the tunnel effect. It was found that the globe-like diamond microcrystalline-aggregates exhibit good electron emission properties, but the microstructure and electrical conductivity have large change before and after the field emission. The good emission properties of the diamond aggregates could be considered to be combined results from the lots of the grain boundaries in the diamonds microcrystalline aggregates. After the field emission, the amorphous carbon become thinner and the globe-like diamonds are not damaged. When the amorphous carbon films are stable, the field emission current could be stabilized accordingly. The results indicated the globe-like diamond has excellent emission characteristics.  

摘要：White LEDs have high power output, high efficiency and long lifetime, and are expected to serve as lighting of the next generation. Visible light LEDs are being used for indoor optical wireless communication system as well as the illumination of rooms. The visible light communication (VLC) system based on LEDs can attain high luminosity as a lighting source, and thus high quality transmission for an optical wireless system. In indoor diffuse optical wireless links multi-path dispersion limits the maximum transmission data rates. White LED light source, SNR, system channel model and RMS delay spread have been analyzed for indoor VLC system. The relation between optimal strategies of light source and received optical power was discussed. SNR of indoor VLC system based IM-DD and ISI produced by multi-path impulse response was investigated. The optical diversity reception technology was given to get rid of ISI and increase the SNR. And the model of the optical detectors layout was given. The system simulation model was built, and the relation curves between BER and RMS delay spread of OOK-NRZ modulation and OOK-RZ modulation were given. Based on the experimental results and under the same received optical power and RMS delay spread time of greater than 1.0 ns, OOK-RZ requires a wider band-width than OOK-NRZs, since it shows a better performance than OOK-NRZ.  

摘要：The dispersion-induced broadening of the optical pulses and nonlinear effects are the adverse limitation in modern optical communications; moreover, high powers can be transmitted without and unwanted nonlinear effects in high-speed and long-haul optical systems. The advent of microstructure fiber affords a novel approach to address these difficulties. For compensating the positive dispersion of the single mode fiber over a wide wavelength range in wavelength division multiplexing systems, the microstructure fiber for broadband dispersion compensation have large negative dispersion magnitudes and proper negative dispersion slope while keeping low nonlinearity. The dispersive and nonlinear properties of the microstructure fiber with hexagonally distributed air-holes in the cladding are numerically simulated by using the vectorial beam propagation method. A microstructure fiber for broadband dispersion compensation with low nonlinearity was designed through separately adjusting the diameters of the inner three air-hole rings and the lattice pitch in the cladding. The proposed microstructure fiber has a large negative dispersion of －3 235.8 ps/nm/km at the wavelength of 1.55 μm, which can compensate (to within 0.5% of the dispersion compensation ratio) the dispersion of 190 times length of standard single mode fiber over the entire 100 wavelength range centered at 1.55 μm. Furthermore, the proposed fiber also can retain the nonlinear coefficient lower than 5 W^-1·km^-1 over this wide wavelength range. The proposed microstructure fiber can be used as function of dispersion-compensating device in high-capacity and long-distance modern optical transmission systems.  

摘要：Silicon oxide is one of the thin films well known in semiconductor industry. It is commonly obtained by chemical vapor deposition (CVD). For this deposition technique, the great disadvantages are high temperature and dangerous reactants as silane (SiH₄), dichlo-rosilane (SiH₂Cl₂), ammonia (NH₃). The reactive magnetron sputtering is a powerful technique for deposition of many different types of films at low deposition temperature. Some of organic (carbon), metallic (tungsten, aluminum, nickel, cobalt, etc.), semiconductor (silicon) and thin dielectric (aluminum oxide) films can commonly be obtained by this method, and furthermore, the advantage is utilization of non-toxic gases, for example, argon, oxygen and nitrogen, high-purity target (99.99%) and it is possible to obtain high deposition rate. In this paper, the silicon oxide films were deposited on quartz substrate by radio-frequency (RF) reactive magnetron sputtering method, the influences of radio-frequency power, oxygen concentration and sputtering pressure on the deposition rate of the silicon oxide film was investigated. It was found that the deposition rate increases with increasing the RF power, but firstly increases and then decreases with increasing oxygen concentration. The deposition rate changed little when the sputtering pressure changed in 0.4~0.8 Pa, and decreases drastically if the pressure is beyond 0.8 Pa. Finally, it was detailedly discused why the deposition rate of silicon oxide films at different growth condition changes.  

摘要：Three main subsystems included in comprehensive control system of solar-energy high-power white-brightness LED street lamp were designed in the paper.The three main subsystem are inversion subsystem of solar power, battery charging subsystem and driving subsystem of LED luminous device. The control techno-logy of the three subsystem were analyzed and studied. Inversion subsystem of solar power was divided into constant current increasing voltage section of DC/DC and inversion section of DC/AC. The technology of MPPT(maximum power point tracker) was adopted to output stable constant current in the control section of DC/DC. The dual-loop control structure was adopted in the inversion section of DC/AC. The voltage was controlled in outer-loop and the current was controlled in inner-loop.And the control technology of reactive power feedback and current feedforward were integrated with dual-loop control technology in the section of DC/AC, too. The method and control technology of sectional charging was adopted in the storage battery charging subsystem to make sure to avoid the storage cells to be overcharged and work in the stable status for long period. The best optimum driving scheme for high power white brightness LED street lamp was defined, that LED street lamp is drived by constant current and the brightness of the street lamp is regulated by PWM technology at last.