最新刊期
卷 41 ， 期 4 ， 2020
- 摘要：The continuous improvement in efficiency of Ⅲ-Ⅴ solar cells requires further detailed subdivision of the bandgap of energy conversion materials, to realize more efficient utilizing of the full solar spectrum. In the short wave infrared spectrum, InGaAsP quaternary hybrid material is a potential photoelectric conversion material due to its tunableness in bandgap and lattice constant. In this paper, the growth of InGaAsP materials and the fabrication of sub-cell devices were studied. The characteristics of lattice-mismatched InGaAsP materials were tested and analyzed by HRXRD, TRPL and other characterization methods at room temperature. Under negative mismatch growth condition, the quality of InGaAsP material increases gradually with the negative mismatch degree. Applied to sub-cell fabrication, a certain degree of negative mismatch is conducive to the improvement of device performance. The open-circuit voltage of the fabricated single-junction solar cell increases from 633 mV at lattice-matching to 684 mV at negative lattice-mismatch, thus providing a novel method to improve the efficiency of Ⅲ-Ⅴ multijunction solar cell.关键词：lattice-mismatch;InGaAsP;MOCVD;solar cell229|477|2更新时间：2020-08-12
- 摘要：In this work, we used metal organic chemical vapor deposition (MOCVD) technology to carry out epitaxial growth of BGaN films on sapphire substrates. We studied the influence of growth thickness, temperature, pressure and B/Ⅲ ratio on the boron content of the BGaN films. X-ray diffraction measurement results demonstrate that lowering the growth temperature, pressure and increasing the B/Ⅲ ratio are conductive to improving the incorporation efficiency of B in BGaN films. At the growth conditions of 800 ℃, 30 kPa and B/Ⅲ ratio of 30%, the B content of the BGaN film is up to the highest with 6.1%.关键词：boron gallium nitride;metal organic chemical vapor deposition;films167|199|0更新时间：2020-08-12
- 摘要：Cerium-doped lutetium pyrosilicate Lu2Si2O7∶Ce nanocrystalline was synthesized by the sol-gel method. The structure, morphologies and scintillation properties of Lu2Si2O7∶Ce nanocrystalline were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), photoluminescence and X-ray excited luminescence. The results indicate that Lu2Si2O7∶Ce starts to crystallize at about 1 000 ℃ and the crystallite size increases with the increasing calcining temperature. Well dispersed, homogeneous and near-spherical Lu2Si2O7∶Ce powder with an average grain size about 28.9 nm was obtained after sintering at 1 200 ℃ for 2 h. The excitation spectrum consists of two intense broad bands at 304 nm and 350 nm, which are corresponding to the 4f→5d transition of Ce3+ ions. The emission peak under 350 nm and X-ray excitation both exhibit a typical asymmetric peak, which are attribute to 5d1→2F5/2 and 5d1→2F7/2 transition of the Ce3+ ions. The optimized doping concentration of Ce3+ ion is about 1%. The decay time of the as-prepared Lu2Si2O7∶Ce phosphor is about 37.2 ns, which can satisfy the requirement of the X-ray detection with high time resolution.关键词：scintillation materials;Lu2Si2O7∶Ce nanocrystalline;sol-gel method;photoluminescence;X-ray detection175|201|0更新时间：2020-08-12
- 摘要：Dense Eu3+-activated oxyfluoride borogermanate scintillating glasses with the nominal composition of B2O3-GeO2-15GdF3-(40-x)Gd2O3-xEu2O3(0≤x≤10) were synthesized by melt-quenching method. The total rare-earth content of Gd2O3 and GdF3 agents is as high as 55% in borogermanate glass matrix, which ensures the glass density exceeding 6.4 g/cm3.Their optical properties were characterized by transmittance, photoluminescence spectra, X-ray excited luminescence (XEL) spectra and luminescence decay curves. The energy transfer of Gd3+→Eu3+ ions were testified by excitation, emission spectra and the mean distances of Gd3+-Eu3+ ion pairs. The optimal concentration of Eu3+-activated borogermanate scintillating glass under both ultraviolet and X-ray excitation was also determined. It was found that the covalency property of Eu―O bond increases remarkably with the increased Eu3+ concentration, which was confirmed by the Judd-Ofelt analysis. Both the temperature-dependent luminescence decay curves and emission spectra of Eu3+ ions in the temperature regions of 80-470 K finally support the stability of luminescent property of the present Eu3+-activated oxyfluoride borogermanate glasses.关键词：Eu3+-activated oxyfluoride borogermanate glasses;photoluminescence;X-ray excited luminescence;Judd-Ofelt theory188|358|3更新时间：2020-08-12
- 摘要：Carbon dots (CDs) are excitation wavelength-dependent and are expected to be a new type pH fluorescent probe. CDs that exhibited bright orange-green dual fluorescence emission bands were solvothermally synthesized in one pot by heating of citric acid (CA) and urea in N, N-dimethylformamide (DMF) at 200 ℃ for 12 hours. The CDs were characterized through transmission electron microscope, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy for composition, phase and morphology. In addition, ultraviolet - visible absorption spectra and fluorescence spectroscopy were used to measure the optical performance for the as-prepared CDs. It was found that the diameter of the CDs ranged from 2.7 nm to 4.3 nm with oxygenous groups on their surface and the CDs had good dispersion in aqueous solution. They showed PL peaks at green (500 nm) and orange (590 nm) under excitation of 440 nm and 540 nm respectively. These kinds of CDs had sensitivity to pH since their PL intensity of 590 nm wavelength in alkaline condition was 6.71 times higher than in neutral water and the UV-Vis absorbance peak showed blue-shifted leading to the color change of the solution. Besides, PL intensity ratio of 500 nm to 590 nm was linear against pH values from 2 to 6 that laid the foundation for the use of CDs in pH sensing applications.关键词：fluorescent carbon dots;solvothermal method;orange-green dual fluorescence emission bands;pH sensing271|338|0更新时间：2020-08-12
- 摘要：Octahedral CeO2∶Er3+ nanophosphors with uniform crystallinity and fine crystalline were prepared using hydrothermal method. The structural and emission properties were investigated. The XRD and Raman spectra indicated that the as-prepared CeO2∶Er3+ samples were cubic fluorite structure of CeO2 phase, and the oxygen vacancies were produced due to the substitution of Er3+ for Ce4+. Green (2H11/2,4S3/2→4I15/2), red (4F9/2→4I15/2) and NIR (4I11/2,4I13/2→4I15/2) emissions under 980 nm laser diode excitation were also investigated, and they were strong affected by the doping concentration of Er3+. Different quenching concentrations are observed in the visible and NIR emission spectra, which is due to the alteration of populating channels in the cross relaxation processes of Er3+.关键词：CeO2∶Er3+;nanophosphor;hydrothermal method;luminescence197|272|2更新时间：2020-08-12
- 摘要：The silver paste SC100-ZnO hybrid film was prepared and introduced as an electron transport layer or a light scattering layer into the polymer solar cells. The effects of different mixing ratios of SC100∶ZnO on the performance of polymer solar cell devices were systematically studied, and the physical mechanism was discussed. The study found that the device parameters (short circuit current density and fill factor) of the devices can be improved by mixing a small amount of SC100 (1% and 2.5%) in ZnO film as a light scattering layer. As a result, the corresponding power conversion efficiency of the devices was improved by 4.4% and 5%, respectively.关键词：light scattering layer;electron transport layer;polymer solar cell179|180|0更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：The short-reach optical interconnection technology has important commercial application value in many fields, such as cloud computing, 5G communication and internet of things technology. The system based on high-speed vertical-cavity surface-emitting lasers (VCSELs) and multi-mode fiber, using direct modulation detection and high-order intensity modulation mode such as four-level pulse amplitude modulation (PAM4) is proved to be an ideal solution for short-reach optical interconnection. In this article, firstly, the research of short-reach optical interconnection is introduced; secondly, the development, structure and dynamic parameters of VCSELs are studied; thirdly, PAM4 modulation method and various electronic technologies (equalization, forward error correction and pulse shaping) are reviewed; fourthly, the wavelength division multiplexing (WDM) technology which can increase the rate of single link is mentioned; lastly, summary and outlook of the short-reach optical interconnection technology based on high-speed VCSEL, multimode fiber, direct modulation detection, PAM4 modulation and WDM are introduced.关键词：vertical-cavity surface-emitting lasers(VCSEL);high-speed modulation;four-level pulse amplitude modulation(PAM4);wavelength division multiplexing(WDM)312|588|6更新时间：2020-08-12
- 摘要：All-solid-state dual-wavelength laser is a single laser emitting two bands of laser at the same time. This type of laser has the characteristics of compact structure, miniaturization, long working time, high energy output, and easy operation. The solid-state dual-wavelength lasers have been widely used in the detection of carbon monoxide in blood, the treatment of capillary dilatation, the interference of rainbow holography, the generation of green light by frequency double, sum frequency mixing for yellow laser and providing pumping source for high-power terahertz radiation. In this paper, several kinds of single-doped Nd3+ laser crystals are compared, the mechanism and method of generating multi-wavelength lasers are analyzed, the research status of single-doped Nd3+ dual-wavelength solid-state lasers is summarized, and the development and application of such lasers is prospected.关键词：solid-state laser;Nd-doped;dual-wavelength216|297|5更新时间：2020-08-12
- 摘要：InGaN/GaN green light-emitting diodes (LEDs) were grown on patterned silicon (111) substrate by metal-organic vapor deposition (MOCVD) method. During the growth process of GaN quantum barrier (QB), the ammonia flow rate was kept constant and the barrier growth rate was reduced by adjusting the three ethyl gallium(TEGa) flow rate. The effect of quantum barrier growth rate on the LED performance has been investigated. It is found that the external quantum efficiency (EQE) increases obviously in the whole range of test current density when the barrier growth rate is reduced. It suggests that the improvement of EQE at low current density can be attributed to the better crystal quality of quantum well and the increase of EQE at high current density is due to the steeper interface between quantum barrier and quantum well.关键词：green LED;quantum barrier;growth rate;external quantum efficiency(EQE)161|262|0更新时间：2020-08-12
- 摘要：Mid-infrared tunable femtosecond fiber laser has attracted many attentions for widely applications. Recently, Raman soliton self-frequency shifting effect in nonlinear fibers was regarded as a promising approach to obtain such pulse laser. However, other higher order nonlinear effects occurred in fibers will limit the pulse energy promoting. So, to further enhance the pulse energy of Raman soliton, we proposed a novel method where the rare-earth doped nonlinear fiber was used as nonlinear medium. We numerically investigated the impacts of the optical gain on the pulse energy, pulse width and spectrum of the wavelength shifting Raman soliton. The results show that as the Raman soliton shifted into the wavelength range where the optical gain introduced, the pulse energy of the soliton pulse was enlarged by several times, and the pulse width was compressed to 45 fs. Meanwhile, the wavelength of the femtosecond Raman soliton pulse can be widely tuned by changing the optical net gain. Therefore, by using rare-earth doped fiber as the nonlinear medium and gain medium, we can achieve the generation of mid-infrared tunable high pulse energy femtosecond pulse laser.关键词：mid-infrared femtosecond pulse;tunable;soliton self-frequency shifting effects;optical gain200|286|3更新时间：2020-08-12
- 摘要：To investigate the effect of temperature rise on the output characteristics of the 915 nm wide strip strain quantum well semiconductor laser, a TEC-based bi-directional temperature control platform was built to test it. First, by changing the temperature of the outer surface of the laser, the power and wavelength of the output beam at different injection currents are measured, and the slow axis divergence angle is measured by a CCD camera. Then, the computer simulation software was used to simulate the working state of the laser, and its steady state heat distribution was obtained. By comparing the simulation results with the measured data, the results tend to be consistent. When the thermal power was increased from 2.1 W to 20.0 W, the slow axis divergence angle increased from 2.6 degrees to 5.0 degrees, and the wavelength of the output light was red-shifted, and the thermal lens focal length of the laser was reduced. The laser has a wavelength temperature variation coefficient of about 0.4 nm/℃, and a thermal resistance of 1.5 K/W. Therefore, in order to obtain high output power and stable output wavelength at the same time, it is necessary to accurately control the temperature of the outer surface of the laser to a certain value, otherwise the wavelength will drift. In addition, when designing and manufacturing a high-power semiconductor laser, the influence on the slow axis divergence angle can be reduced by appropriately increasing the strip width and using a heat-dissipating package structure.关键词：semiconductor laser;thermal lens;thermal analysis;slow axis divergence angle181|365|1更新时间：2020-08-12
- 摘要：With the wide application of thin-film transistor (TFT) in various emerging electronic products, as a key component of various electronic equipment, its operating voltage and stability are facing great challenges. In order to meet the needs of highly integrated and complex applications in the future, it is very important to realize its low operating voltage and high stability. Bottom gate top-contact a-IGZO TFT on large area glass substrate of 150 mm×150 mm was prepared by using magnetron sputtering to investigate the effect of 50, 40, 30 and 20 nm Al2O3 thickness on the performance of a-IGZO TFTs. The results show that TFT with 20 nm-thick-Al2O3 gate insulator exhibits the best electrical comprehensive performance: low operating voltage of 1 V, threshold voltage of nearly 0 V and subthreshold swing of only 65.21 mV/dec. It also has a high field-effect mobility of 15.52 cm2/(V·s) and a high ION/IOFF ratio of 5.85×107. At the same time, the device also shows excellent stability: the minimum threshold voltage shift after 1 h of gate ±5 V bias is only 0.09 V and excellent stability of uniform distribution over a large area of 150 mm×150 mm. The low operating voltage and high stability of TFT devices are realized. Finally, a common-source amplifier is designed with this TFT device, and a gain of 14 dB is obtained.关键词：a-IGZO TFT;Al2O3 gate insulator;ALD;common-source amplifier242|377|2更新时间：2020-08-12
- 摘要：In this paper, we studied the effect of growth temperature on InGaN/GaN superlattice preparation layer of GaN based yellow LED on Si substrate including photoelectric and aging properties. It was found that the external quantum efficiency of the sample with higher growth temperature of the preparation layer was higher than that of the samples with the lower growth temperature. After 1 000 h of aging at 500 mA, the light decay of the samples with higher growth temperature of the preparation layer is relatively larger. The electroluminescent spectra of 100 K before and after aging showed that the hole injection pathway of high-temperature-grown sample changed after aging, and the non-radiative composite center of high-temperature sample increased more after aging. Fluorescence microscope showed that a large number of dark spots appeared before aging, the color of high-temperature sample was darker, and the color of low temperature sample was lighter and red. The number of dark spots of high-temperature sample increased after aging, but the quantity of low temperature sample did change small, which may also be one of the reasons for the higher light decay of samples with high superlattice temperature.关键词：Si substrate;yellow light-emitting diode;reliability155|302|0更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：At present, the LED light source module used in the plant factory growing shelf has simple optical structure, so the illumination uniformity and color-mixed uniformity are difficult to ensure,which lead to uneven quality of crops. In order to improve the quality of the plant, it is necessary to optimize the illumination effect of the plant light source, and design a high uniformity plant light source. To this problem, this essay proposes and studies a design scheme of the plant growing shelf with inverted light source. The LED lamp bead is placed on the same side of the planting surface,and the light emitted by the LED is further uniformly distributed in combination with the curved reflecting top. This method increases the coupling distance and coupling degree of the light in the limited planting space of the plant growing shelf, thereby improving the uniformity of the plant light source. After several structural optimizations, a plant lighting growing shelf is obtained, whose illumination uniformity is 91.64% and color-mixed uniformity is 89.73% finally. Based on the plant light source, studying the influence of plant growth process on the lighting effect shows that the plant can obtain a good lighting environment during the growth process. At last, the effects of different shapes and different light distribution curves on the growing shelf’s uniformity and light efficiency are studied.关键词：LED;plant lighting;optical design;Taguchi;ANOVA160|222|3更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
- Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China Postal code：130033
- Tel：0431-86176862 Email：fgxbt@126.com
- Technical support is provided by Beijing Founder electronics co., LTD 吉ICP备11002662号-17
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0