最新刊期
卷 37 ， 期 7 ， 2016
- 摘要：A series of yellow-green emitting phosphors Ca1-xMoO4:xDy3+ (0< x≤ 0.12) and Ca0.98-(MoO4)1-1.5y(PO4)y:0.02Dy3+ (0≤ y≤ 0.10) were fabricated via microwave radiation method. The phase structure, morphology and luminescence properties of the as-fabricated samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer, respectively. The results reveal that the obtained CaMoO4:Dy3+ phosphor powders are well assigned to the tetragonal scheelite-type similar to that of CaMoO4. The particles are approximately cubic in shape with the side length about 5μm, and cubic big particle is composed by a large number of spherical-like particles with a diameter of about 120-540 nm. The maximum excitation peak of CaMoO4:Dy3+ is located at 300 nm. The emission spectrum is composed of a series of sharp peaks with the strongest emission peak at 572 nm, which is ascribed to the 4F9/2→6H13/2 transition of Dy3+. The fluorescence intensity firstly increases with the increase of Dy3+ concentration in CaMoO4 host and then decreases. The optimum luminescence is observed when the mole fraction of Dy3+ is 0.02. When the mole fraction of Dy3+ exceeds 0.02, luminescence intensity reduces obviously due to the concentration quenching. The mechanism of concentration quenching is mainly caused by the electric dipole-dipole interaction and the cross relaxation between Dy3+ ions. Under 254 nm excitation, the chromaticity coordinates of CaMoO4:Dy3+ are concentrated in yellow-green region. In addition, the emission intensity of the CaMoO4:Dy3+ system is improved effectively by the doping of anions (PO43-). The optimum content(y) is about 0.04 and the luminescence intensity is enhanced about 19% than that of the undoped.关键词：CaMoO4:Dy3+;PO43-;microwave radiation method;luminescence101|51|2更新时间：2020-08-12
- 摘要：Using RF magnetron sputtering technique and thermal annealing, a-Si/SiNx superlattice was fabricated. The absorption measurement and X-ray diffraction show that the Si layer is amorphous. The Z-scan technique is used to research the nonlinear optical properties of a-Si/a-SiNx superlattice. The results indicate that the nonlinear absorption is counter-saturated absorption and the nonlinear refractive index of the sample is a negative value. Moreover, the real and imaginary parts of χ(3) have been calculated to be 4.57×10-17 C(1.39×10-7 esu) and 1.49×10-17 C (4.48×10-8 esu), respectively, which exceeds the value of bulk silicon by more than five order of magnitude. The enhancement of nonlinear refractive index of Si/SiNx superlattice is mainly attributed to intensive quantum confinement.关键词：a-Si/SiNx superlattice;nonlinear optical;Z-scan;quantum confinement81|46|0更新时间：2020-08-12
- 摘要：Due to its special structure, graphene has very good optical, electrical, mechanical and other properties, and it is regarded as a breakthrough of the new materials. Thanks to the wide band gap, thermal stability, high working power and other properties, GaN based materials have become "the most important, after the silicon semiconductor material." It will bring great benefits for the photoelectric and microelectric devices if the graphene can be successfully combined with GaN based materials. There have already been some breakthroughs in the research of combination of graphene and GaN based materials. This paper briefly summarized recent findings of physical mechanisms of the contact between graphene and GaN-based materials and the researches of the applications of graphene to the GaN-based materials.关键词：graphene;GaN-based materials;graphene contacts with GaN-based material107|79|2更新时间：2020-08-12
- 摘要：SrSnO3:Sm3+ down-converted powders were prepared by hydrothermal method with Sr(NO3)2 and NaSnO3 as raw materials. SrSnO3:Sm3+/TiO2 composite photoanode was used in dye-sensitized solar cells (DSSC). X-ray diffractometer (XRD), scanning electron microscope (SEM), energy spectrum analyzer (EDS) and fluorescence spectrometer (FL) were used to characterize SrSnO3:Sm3+. The effects of SrSnO3:Sm3+ doping amount on the photoelectric properties of DSSC based on SrSnO3:Sm3+/TiO2 composite photoanode were explored. The results show that SrSnO3:Sm3+ of mixing rod, short columnar and particle morphology are prepared successfully by hydrothermal method. The as-prepared SrSnO3:Sm3+ can convert UV-light to yellow light (587 nm) and widen the spectra response range. With the increasing of SrSnO3:Sm3+ mass fraction in SrSnO3:Sm3+/TiO2, the short current density of DSSC increases significantly. When the mass fraction of SrSnO3:Sm3+ is 3%, the short current density and photoelectric conversion efficiency are 10.3 mA/cm2 and 4.09%, increase by 38% and 25% respectively compared with the pure P25.关键词：SrSnO3:Sm3+;down-conversion;dye-sensitized solar cells;photoelectric performance99|45|1更新时间：2020-08-12
- 摘要：In order to obtain the diamond cones with high field emission property, the etching characteristics of high-quality diamond thick film and nano-crystalline diamond films were studied by using the bias voltage assisted hot filament chemical vapor deposition (BA-HFCVD) method, the diamond cones with high aspect ratio of 20:1 in a large area were fabricated by optimizing etching condition, in addition, the formation mechanism of the diamond cone was studied in detail.关键词：diamond cone;BA-HFCVD;plasma etching102|85|1更新时间：2020-08-12
- 摘要：The plane wave ultra soft pseudo potential method based on the first principle is used to calculate the optical properties of GaN epitaxial materials caused by point defects after electron irradiation. First, the properties of the intrinsic GaN crystal are calculated as a reference for the study of the variation of the defect properties. The effects of the defects of VN, VGa, GaN, MgGa, MgGa-ON, MgGa-VN, VGa-ON on the optical absorption spectra are emphatically analyzed. As the InGaN multi quantum well is the main source of LED emission, the optical properties of GaN doped with different In mole fraction are also studied. The results show that VN, GaN and doing of In make the GaN absorption peak red shift and the absorption coefficient decreases. VGa, MgGa, MgGa-ON, VGa-ON all make the main absorption peaks of GaN appear blue shift. MgGa defect makes the main absorption peak's value increase, and the remaining defects make the main peak absorption coefficient decrease. MgGa-VN only decreases the main peak value, does not change the photon absorption wavelength. It is confirmed that the defects can make the material properties change after electron irradiation.关键词：first-principles calculation;electron irradiation;GaN;point defects;optical properties83|97|2更新时间：2020-08-12
- 摘要：The stress accelerated aging test and analysis are the most efficient and effective way to analysis the reliability of the devices. In this paper, the same 6 V LED modules were divided into two groups for aging. 180 mA stress current and 85℃ high temperature were applied for one group, and 180 mA stress current and 85℃/85%RH moisture condition for another. During the aging time, the optical and electrical characteristics of the LEDs were measured and analyzed. The experimental results show that the degradation rate of the samples which under high temperature and high current stress is 3.4%-0.9%, and the degradation rate of the samples which under high humidity, high temperature and high current stress is 25.4%-27.8%. The degradation of LEDs under high temperature and high humidity condition is more serious than that under high temperature. So it is strong evidence that the humidity badly affects the reliability of LEDs. The failure reasons include the degradation of the phosphor and the Ohmic contact in the devices.关键词：white LED;aging;luminous flux;light decay79|89|1更新时间：2020-08-12
- 摘要：The vertical-cavity surface-emitting laser(VCSEL) is becoming a key device in the gigabit, local-area networks(LANs) and optical interconnets. Its volumn is increasing ever year in the world. However, there is no company to produce this promising device in China. In this paper, we review its material system properties and fabrication technology of 1310 nm long-wavelength band and analyse the advantage and disadvantage from production. Lastly,we give a conclusion which method is better choice in the industrlization.关键词：vertical cavity surface-emitting lasers;1 310 nm;industrialization101|94|2更新时间：2020-08-12
- 摘要：An amorphous silicon thin-film solar cell with an anti-reflection coating of light cone photonic crystal and a back surface field layer of rectangular pyramid grating is proposed. The thickness of the cell is 1.45μm and the thickness of the absorbing layer is 1μm. Using Rigorous Coupled Wave Analysis method, the parameters of the cell are optimized based the diffraction characteristics of the photonic crystal and the sub-wavelength grating. When the light cone angle is 72°, the lattice constant is 1200 nm, and the bottom radius is 100 nm, a relative increase of 11.54% for the integrated absorption inside the solar cell can be achieved between 300 nm and 600 nm, compared to an equivalent but no anti-reflection coating cell. When the rectangular pyramid grating period is 1.2μm, the duty cycle is 0.38, and the depth of the grating is 560 nm, a relative increase of 3.75% for the integrated absorption inside the solar cell can be achieved between 600 nm and 850 nm. According to the simulation, the absorption of the designed thin-film solar cell is over than 80% in the incident angle range of 0°-75° and the wavelength between 300 nm and 750 nm, and the average absorption is up to 92%. This solar cell is designed to meet the demanding requirements of a wide spectrum and wide-angle light capture.关键词：thin-film solar cell;photonic crystal;sub-wavelength grating;rigorous coupled wave analysis;diffraction efficiency413|112|6更新时间：2020-08-12
- 摘要：The electroluminescent devices with the structure of ITO/PEDOT:PSS/polyvinylcarbazole (PVK)/carbon quantum dots(CDs)/LiF/Al were fabricated. When the voltage raises from 7 V to 13 V, the voltage-dependent EL spectra can be observed to shift from 380 nm to 520 nm, and the color coordinates shift from (0.20, 0.20) to (0.29, 0.35). The device operating mechanism is investigated based on PL spectra of PVK and CDs and device energy-level diagram. PVK layer is considered to be responsible for electron blocking and meanwhile the emission in low electric field. The EL spectra are proposed to be the overlapping of PVK and CDs and their interface. With the voltage increase, the emission intensity of CDs displays enhancement but the converse trend is observed for PVK. Under high field, electroplex emission at PVK/CDs interface is known to contributed to whole EL spectra combining with CDs emission.关键词：carbon quantum dots (CDs);electroluminescence(EL);charge transport107|80|1更新时间：2020-08-12
- 摘要：GaN-based blue light emitting diodes (LEDs) were grown on patterned sapphire substrates by metal-organic chemical vapor deposition (MOCVD) method, and the medium-high temperature GaN interlayer with different thickness was grown between the multiple quantum wells layer and n-GaN layer. The Optical and electrical properties and surface morphology of LEDs were characterized by LED test system and atomic force microscopy(AFM), respectively. When the thickness of the medium-high temperature GaN interlayer increases from 60 nm to 100 nm, the size of V-pit enlarges from 70-110 nm to 110-150 nm. Meanwhile, the light output power of the chip increases from 21.9 mW to 24.1 mW with the injection current of 20 mA, and 72.4 mW to 82.4 mW with the injection current of 120 mA. In order to better illustrate the influence mechanism of the size of V-pits on the photoelectric properties of the LEDs, the schematic structures with different V-shaped pit sizes are demonstrated. The analyzing results for the LED samples show that the increase of the V-pit size is beneficial to enhance the hole injection area and injection efficiency. Thus, the light output power of the LED device is improved.关键词：GaN;LED;V-pits;hole injection efficiency249|56|2更新时间：2020-08-12
- 摘要：Optimization of LED epilayer and photonic crystals (PC) structure for high light extraction efficiency (LEE) UV-A vertical-structure LEDs (VS-LEDs) were performed by using finite difference time domain method. The LEE of the VS-LEDs was markedly enhanced by optimizing the thicknesses of p-GaN layer and parameters of PC structure. The LEE of the VS-LEDs shows cyclic variation as function of the thicknesses of p-GaN layer. It is showed that the LEE of the VS-LEDs with the p-GaN thickness of 200 nm is 4.8 times to that of the VS-LEDs with the p-GaN thickness of 310 nm. In addition, the thickness of the n-GaN layer and the surface photonic crystal structure were further optimized, and the LEE of the VS-LEDs with the p-GaN thickness of 200 nm and 310 nm reaches 35.3% and 24.7%, respectively. The optimized LEE of the VS-LEDs is 1.4 and 3.8 times to that of the VS-LEDs without PC structure, respectively. Therefore, the reasonable LED epilayer and the PC structure can effectively improve the LEE of the VS-LEDs. It provides a theoretical guide for the preparation of the UV-A VS-LEDs.关键词：light-emitting diodes;light extraction efficiency;ultraviolet-A;photonic crystals;resonant cavity effect139|94|2更新时间：2020-08-12
- 摘要：In order to realize long distance and broadband transmission of terahertz wave, a double-cladding terahertz photonic crystal fiber was designed based on Topas cyclic olefin copolymer with low loss. The single-mode transmission range, confinement loss, dispersion and effective area of the double-cladding terahertz photonic crystal fiber were investigated by using the full-vector finite element method (FEM) and the mode choice theory. The results show that the confinement loss of the fundamental mode is far less than 0.1 dB/m and the confinement loss of second-order mode loss is larger than 1 dB/m at frequency range of 1-10 THz by tailoring the structure parameters. The broadband single mode transmission operates at bandwidth of 1-10 THz, and the group velocity dispersion (GVD) can be controlled at ±0.1 ps/(THz·cm) in the range of 1.5-10 THz.关键词：terahertz;photonic crystal fiber;single mode;confinement loss;dispersion119|62|1更新时间：2020-08-12
- 摘要：This paper introduces a new visible light/audio transmission system, which contains a transmitter module, a receiver module and optics. In transmitter module, a mobile phone is used to generate audio signals which modulate the LED light emission; In the receiver, a C12702-11 APD module converts the received optical signals into electrical signals which can make the sound broadcast clearly through the related amplifying and filtering processing. By using plane mirrors for light reflection and a lens to focus light, this system can achieve more than 5 m distance of communication.关键词：VLC;audio transmission;white LED;C12702-11 APD module125|117|1更新时间：2020-08-12
- 摘要：A virtual system based on TDLAS to detect the concentration of dust containing gases was designed by LabVIEW. The concentration of SO2, NO2 and NO is measured at ambient temperature and pressure and environment of known dust particles, and the gas composition measuring results are not affected by dust. Three kinds of infrared laser of 2516.2, 2911.66, and 3752.44 cm-1 are used to detect SO2, NO2 and NO. According to the principle of phase locked loop, the two harmonic signals detected by multi channel lock-in amplifier are analyzed, and the concentration of each gas is measured using the second-harmonic signal calibration. Finally, the interference of dust particles is eliminated through data correction, so as to get stable results.关键词：system simulation;laser theory;infrared spectroscopy;absorption spectrum;dust containing gases detection118|91|7更新时间：2020-08-12
- 摘要：The interactions between colistin sulfate(CLS), cefpirome sulfate(CFS), cefpiramide sodium(CFMS) and bovine serum albumin(BSA) were investigated by fluorescence quenching spectroscopy (FQS), synchronous fluorescence spectroscopy (SYS), resonance light scattering (RLS) and UV absorption spectroscopy at 298 K with the simulated physiological condition of the body. The results show that the binding constants of BSA-CLS, BSA-CFS and BSA-CFMS obtained from four methods are at the same order of magnitude, and the quenching mechanism is a static quenching process. The number of binding site (n) in the three system is approximately equal to 1, and the values of Hill's coefficients in the three system are approximately consistent. The comparison to the experimental data for four methods indicates that FQS, SYS seem to be more suitable for the studying of the reaction mechanism of protein and drug.关键词：bovine serum albumin;fluorescence quenching spectroscopy;synchronous fluorescence spectroscopy;resonance light scattering spectroscopy;UV-Vis absorption spectroscopy78|68|2更新时间：2020-08-12
- 摘要：A new Schiff base was synthesized from furaldehyde and sulfanilic acid, and rare earth complexes of this ligand were prepared with it. The interactions of the rare earth complexes with DNA were investigated by spectroscopy method, which could provide the basis for the design and development of new anticancer drugs. The ternary complexes were characterized by elemental analysis, IR, and UV-Vis methods. The results show that the composition of these coordinated compounds is REL(OH) (RE=La3+, Nd3+, Eu3+, L=deprotonated ligand of Schiff base). Meanwhile, the interaction between complexes and herring sperm DNA was investigated by cyclic voltammetry and UV-Vis spectra. The absorption intensity of herring sperm DNA decreases with the adding of complex, and the maximum absorption peak has a red shift. The peak current of probe molecule Fe(CN)63-/4- at Au/DNA electrode obviously decreases and the peak potential shifts positively because of the existences of complex. The results show that there is a competitive effect between complex and Fe(CN)63-/4- with herring sperm DNA, and a binding mode intercalation is interacted between complex and herring sperm DNA, thus leads to the change of DNA conformation.关键词：Schiff base;rare earth complex;DNA;cyclic voltammetry;spectra method127|80|2更新时间：2020-08-12
- 摘要：A fluorescent aptamer biosensor was constructed for the determination of dopamine. The dopamine aptamer modified 6-carboxyfluorescein (FAM) was used as the recognition element, and graphene oxide was the quencher. Through π-π stacking interaction, FAM energy can be transferred to the surface of the graphene oxide in resonant manner, and the fluorescence disappears. In the presence of DA, the fluorescence can be recovered and the fluorescence intensity is found to be in proportion to the concentration of DA. The optimized research results show that 10μg/mL graphene oxide may achieve maximum quenching efficiency within 5 min reaction time. The fluorescence intensity can reach a stable recovery after 25 min incubation. The response to dopamine proves to be linear with the correlation coefficient up to 0.988 in the relevant concentration range of 1-500 μmol/L, and the detection limit is 1 μmol/L. The biosensor is characterized by its wide range of measurement, fast detection, low cost and so on.关键词：graphene oxide;fluorescence;aptamer biosensor;dopamine107|93|7更新时间：2020-08-12
- 摘要：The effects of material loss on light propagation in heterostructure comprising of two single-negative layers were studied, with the aim of light manipulation based on loss. Firstly, transmission of a single-negative layer was calculated, and the variation of the non-monotonic transmission with the dissipation coefficient in the structure was given. Then, the relationships of the transmission, reflection and absorption with the dissipation coefficient in the double layer heterostructure of the two single-negative materials were dicussed, and the variation of the transmission at different frequency was analyzed. Finally, the distribution of the electromagnetic field intensity was shown in order to explain the anomalous transmission phenomenon with the dissipation coefficient. The results illuminate that the anomalous nonmonotonic transmission behavior with the increasing of dissipation coefficient remains in the double layer heterostructure of the single-negative materials, only at the far from tunneling frequencies. This reason is the anomalous localized fields in the interface between two different single-negative materials.关键词：single-negative materials;optical property;heterosturcture92|73|0更新时间：2020-08-12
- 摘要：By using the physiological parameters method, the human non-visual effects were researched with the college students as objects. The LED dimming method included PWM and analog. The experiment condition included three levels of color temperature (3000, 5600, 6500 K) of white LED light source with three levels of illumination (300, 500, 800 lx). The pulse and pupil size of eight subjects (5 males and 3 females) were measured in black and white LED light with three levels of color temperature. Using the same three levels of color temperature white LED light sources and adding blue light (464 nm, 20 lx) to achieve lighting environment of 300 lx, the pulse and pupil size of twelve subjects (8 males and 4 females) were tested. The results show that the impact of lighting environment created by two dimming methods on human pulse change rate and pupil contraction rate have no significantly different, and adding blue light in testing environment can cause the pulse change rate and pupil contraction rate to increase for about 6% and 9%, respectively.关键词：non-visual effects;LED;PWM dimming;physiological parameters;color temperature252|69|8更新时间：2020-08-12
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