最新刊期
卷 40 ， 期 9 ， 2019
- 摘要：In this paper, the radiation effects of In0.53Ga0.47As solar cell grown by MBE method irradiated by 1 MeV electron with high fluence irradiation have been studied. The degradation properties of cell parameters have been analyzed by Mulassis simulation result and the method of I-V curve mathematically fitting. The results show that the value of Non-ionizing energy loss (NIEL) increases with the increase of electron incident depth in the active region of solar cell under electron irradiation. The electrical parameters of In0.53Ga0.47As solar cell, Voc, Isc, Pmax and FF, degraded in different scale with the increase of fluence. When the fluence reaches 61016 e/cm2, the photoelectric conversion efficiency of the solar cell is zero, and the performance of the cell is invalid. For spectral response, when the fluence is less than 41016 e/cm2, the degradation of long-wave region is more serious than that of short-wave region. When the fluence is greater than 41016 e/cm2, the degree of degradation of the long-wave region is substantially the same as that of the short-wave region. The decrease of minority carrier diffusion length and carrier removal effect caused by displacement damage are the main reasons for degradation of solar cell performance.关键词：InGaAs single junction solar cell;high fluence electron;displacement damage;carrier lifetime;carrier removal effect136|223|1更新时间：2020-08-12
- 摘要：This study was to investigate the dependence of internal quantum efficiency of GaN-based yellow light-emitting diodes(LEDs) with Si substrate on the Al composition of first electron blocking layer(EBL-1) in dual electron blocking layer design and the main physical mechanism of carrier injection. First, three samples were prepared by the technology of GaN-based yellow LEDs on silicon substrates with different flows of trimethyl aluminum(TMAl) during epitaxy. As a result, the Al composition in EBL-1 of the samples was about 20%, 50% and 80%, respectively. Then, the actual tested internal quantum efficiency curves of these three samples were fitted by the semiconductor simulation software Silvaco Atlas. The results show that EBL-1 in dual electron blocking layer design has two main influences on the internal quantum efficiency. One is that EBL-1 with a higher Al composition allows more holes to be injected from the sidewall of the V-shaped pits into the multiple quantum wells, and the other is that excessive aluminum composition reduces the quality of p-type GaN layers, resulting in a decrease in the effective concentration of holes. As a comprehensive performance, the EBL-1 with about 50% Al composition is the most benefit in dual electron blocking layer design to the internal quantum efficiency of GaN-based yellow LEDs.关键词：GaN;yellow LED;electron-blocking layer;technology computer aided design(TCAD)200|251|1更新时间：2020-08-12
- 摘要：Significantly improved external quantum efficiency was achieved by growing an additional optimized 25 nm low-doped p-AlGaN interlayer(IL) after the conventional p-AlGaN electron blocking layer for InGaN/GaN green LEDs with V-pits on Si(111) substrate. At 35 A/cm2 current density, external quantum efficiency(EQE) and output power reach up to 43.6% and 362.3 mW with the dominant wavelength of 520 nm. This is a new record for green InGaN-based LEDs. The underlying physical mechanism is attributed to the enhanced holes injection efficiency via V-shaped pits assisted by the optimized p-AlGaN interlayer. This paper provides an effective approach to improve efficiency especially suitable for those InGaN/GaN LED with V-shape pits.关键词：green LEDs;p-AlGaN interlayer (IL);external quantum efficiency;V-shaped pits;holes injection efficiency226|198|0更新时间：2020-08-12
- 摘要：The 780.0 nm narrow linewidth and high power diode laser is of great significance for the development of Rb alkali metal vapor laser. In order to obtain good pumping effect, the absorption spectra of the pump spectrum and the alkali metal vapor must be strictly matched, the output line width of the diode laser must be narrowed, and the central wavelength must be stabilized. External cavity feedback of reflective volume Bragg grating(RVBG) is one of the main schemes to realize narrow spectrum light source at present. The structure of fast axis collimating mirror, beam convertor, slow axis collimating mirror, reflection type body Bragg grating(FAC-BTS-SAC-RVBG) is proposed. The laser divergence angle of incident to RVBG is compressed to improve the effective response rate of RVBG. Compared with the conventional "FAC +SAC+RVBG" structure, the spectral locking effect is improved. Based on the FAC-BTS-SAC-RVBG structure, a narrow linewidth laser at 780 nm was developed, with a continuous power of 50 W. By controlling RVBG temperature, the central wavelength could be stabilized at 780.00 nm. Using single mode optical fiber probe, spectral width is 0.064 nm(FWHM), temperature drift coefficient is 0.001 2 nm/℃, current drift coefficient is 0.001 3 nm/A. The structure can be used for Rb alkali metal vapor laser pump.关键词：diode laser;narrow linewidth;reflective volume Bragg grating(RVBG);diode laser pumping alkali metal vapor laser(DPAL)190|224|5更新时间：2020-08-12
- 摘要：The laser holography photolithography technology was designed, the optical path of holography lithography system was calculated and built based on the designed parameters of cavity grating, and the holography lithography conditions were optimized to fabricate the mask patterns of cavity grating. Based on the design of facet coating films, the facet coating process was investigated by precisely controlling the thickness and uniformity of films to realize the transmissivity, reflectivity, and bandwidth satisfied with the single longitudinal mode output of 808 nm facet grating LD. The single chip device of 808 nm facet grating LD was fabricated and characterized, with width of 100 μm and length of 2 mm. High performance was achieved with central wavelength of 807.32 nm, FWHM of 0.36 nm, wavelength drift coefficient with temperature variation(15~45℃) of 0.072 nm/℃, maximum output power of 2.8 W, threshold of 0.49 A, and slop efficient of 1.05 W/A.关键词：semiconductor laser;wavelength locking;facet grating;holography lithography183|202|1更新时间：2020-08-12
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Thermally Accelerated Aging Test of Conduction-cooled-packaged High Power Diode Laser Bar in CW Mode
摘要：In the applications of high power semiconductor laser(HLD), the reliability is the important performance. Therefore lifetime evaluation and reliability analysis technologies become the key of practical application and industrialization of HLD. The thermally accelerated aging test is able to monitor the failure process, reveal defects and weak links of device design process, materials and components, and provides guidance for optimizing the chip and package structure. It is an important technology of lifetime evaluation and reliability analysis. In this work, a thermally accelerated aging test of eighteen conduction-cooled-packaged 60 W 808 nm high power diode laser arrays packaged by indium solder in CW mode at constant current 60 A under the temperature 55, 65, 80℃ of heat sink has been reported. According to the decreasing trend of the output power during the thermal acceleated aging test, the lifetime 1 022, 620, 298 h have been obtained, respectively. Based on the Arrhenius formula, the activation energy of the device is 0.565 41 eV, and the lifetime of the device is 5 762 h at room temperature. It can be seen that the lifetime of the device accelerates by 5 times at 55℃, 8.5 times at 65℃ and 17 times at 80℃. In addition, we show and analyze the performance of the device after accelerated aging test.关键词：high power semiconductor laser;thermally accelerated ageing test;reliability;degradation215|481|4更新时间：2020-08-12 - 摘要：Compared with traditional technology, inkjet printing as a cost effective, direct patterning and noncontact deposition technology, can be used to directly pattern conductive materials onto substrates leading to less process time and lower material cost, and shows incomparable potential in the manufacture of flexible electronic devices. To meet the demand of low-temperature manufacture of flexible electronic devices, not only the fabrication of low-temperature and high performance conductive materials but also the low-temperature applications of sintering technologies should be taken into consideration. This paper offers a retrospection of the research efforts in inkjet printing flexible electrodes, and provides elaborate descriptions about conductive materials and low-temperature applications of sintering technologies. The problems restricting the applications of different conductive materials and sintering technologies in flexible electrodes are paid attentions, and the future direction of inkjet printing flexible electrodes is pointed out.关键词：inkjet printing;flexible;electrode;low-temperature fabrication335|386|1更新时间：2020-08-12
- 摘要：The white filed display quality of LED panel is increasingly focused. The white field display quality is mainly the luminance and chromaticity, and the primary luminance of the LED panel is one of the important factors affecting the luminance and chromaticity of the white field. In order to obtain the mathematical relationship between primary luminance and brightness and chromaticity of white field, quantificat the deviation of luminance and chromaticity of the white field caused by primary luminance deviation, according to establish the mapping model of the three primary luminance and the luminance and chromaticity of the white field in the CIE-Yxy color space, this paper obtains the spatial model of deviation of the luminance and chromaticity of the white field deviation caused by the brightness variation of red, green and blue primary individually or compounded. The influence on luminance and chromaticity of the white field by the primaries variation has been analyzed in the orthographic plane of the color space model. The mathematical relationship has a general form in CIE-Yxy color space, and can quickly determine the deviation of luminance and chromaticity of white field caused by the variation of primary luminance of any LED panel.关键词：primary luminance;luminance and chromaticity of the white field;deviation of the luminance and chromaticity200|318|2更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：In order to improve the stability of CsPbBr3 perovskite quantum dots and realize the preparation of solid quantum dot materials with excellent luminescence properties, CsPbBr3 quantum dots were successfully prepared in the borosilicate microcrystals by high temperature melting method to obtain CsPbBr3 quantum dot microcrystals. The particle morphology of the microcrystals was tested by scanning electron microscopy(SEM). The fluorescence characteristics were analyzed by fluorescence spectroscopy and CIE chromaticity coordinates. SEM images show that CsPbBr3 quantum dots with a particle size of about 10 nm are uniformly distributed on the surface and inside of the microcrystals, and the effective coating of CsPbBr3 quantum dots by borosilicate microcrystals was realized. Fluorescence spectroscopy tests show that CsPbBr3 quantum dot microcrystals exhibit a broad excitation spectrum and can achieve strong 517 nm green emission at 360 nm wavelength excitation. The emission spectra and CIE coordinates indicate that the CsPbBr3 quantum dot microcrystals can maintain excellent optical properties at 400℃. The successful preparation of the quantum dot microcrystalline material provides the possibility for the development of perovskite materials in the field of new solid luminescent materials.关键词：CsPbBr3;borosilicate;quantum dots;perovskite;luminescence properties277|383|8更新时间：2020-08-12
- 摘要：We studied a new type of stealth photonic crystal films compatible for visible, far infrared, 1.06 μm laser and 10.6 μm laser, for the purpose of minimizing the threats to important military targets from visible, infrared and laser detectors. In this paper, firstly, three kinds of compatible stealth photonic crystals with different colors were designed and simulated by transfer matrix method(TMM), and then fabricated by vacuum electron beam evaporation coating technique. Finally, we tested them by using relevant instruments and obtained scanning electron microscope(SEM) photos, visible photos, infrared thermogram and reflectance spectrogram. The result shows that the bonding between layers of films is compact and the thicknesses conform to the theoretical design. The prepared photonic crystal films possess optical characteristics of cyan, yellow or violet, which can be used to form camouflage patterns to segment visible images. In addition, the average emissivity in 8-14 μm far infrared atmospheric window is less than 0.3, which can effectively suppress far-infrared radiation. The reflectivity at wavelength of 1.06 μm and 10.6 μm keeps at about 10% and 40%, respectively, which will enormously reduce the reflected power of the incident lasers.关键词：photonic crystal;visible light;far Infrared;laser;compatible stealth252|662|4更新时间：2020-08-12
- 摘要：(Mg1-xSrx)2-ySiO4(x=0~1) powder was prepared at 1 150℃ by high temperature solid-state method. As Sr ion content in matrix increasing, the phase constitutions change from γ-Mg2SiO4, β-Mg2SiO4 mixture(x=0) to α-Sr2SiO4, β-Sr2SiO4, γ-Mg2SiO4, β-Mg2SiO4, Sr3MgSi2O8 mixture(0.2 ≤ x ≤ 0.8), then to α-Sr2SiO4, β-Sr2SiO4 mixture(x=1). Furthermore, when x=0.2, the main phase is β-Mg2SiO4, while x=0, the main phase is γ-Mg2SiO4. UV light excitation and luminescent spectra analysis show (Mg0.8Sr0.2)1.96SiO4:0.04(Eu3+,F-) has been picked out as the best red phosphor composition among (Mg1-xSrx)1.96SiO4:0.04(Eu3+,F-). Sr ion would go into β-Mg2SiO4 crystal lattice, and makes the phase more stable. When the annealing temperature reaching at 1 250℃, the powder has the composition as (Mg0.8Sr0.2)2SiO4 would be single phase as β-Mg2SiO4. (Mg0.8Sr0.2)2-ySiO4:y(Eu3+,F-) series(~21.68 μm) have red-band emission peaks at 595, 615(main), 655, 705 nm(related to5D0→7Fn, n=1, 2, 3, 4) under 365 nm or 254 nm excitation, and the most suitable Eu3+ doping amount is 4%(the quantum yields and lifetime both reaching to maxium value among the series). Based on Blasse theory, the main energy transfer mode for activators should be the four electric dipoles(q-q).关键词：alkaline earth silicate;crystal structure;photoluminescent spectra;energy transfer168|149|2更新时间：2020-08-12
- 摘要：Fano resonances in Ag-Air-SiO2 nanostructure were investigated by Finite-difference time-domain (FDTD). It could be observed a redshift with the growth of horizontal length l of silver film for the resonance peaks of the modes mj(j=2, 3). Fano resonance was related with the Ag-Air-SiO2 periodic structure and SiO2. The modes mj (j=2,3) presented a redshift and the Fano was becoming more and more obvious with the increment of transverse length L of SiO2. In addition, the Fano resonances were also closely related with the permittivity (negative value of the real part) of the silver film. The Fano resonances could be obtained when -εm'=4 000 and -εm'=6 000 in the aperiodic Ag-Air-SiO2 structure.关键词：Fano resonances;Ag-Air-SiO2;nanostructure163|123|0更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：At present, the existing plant factory placed the light source at the top, and the plant was planted at the bottom. The uniformity of illumination and the uniformity of color mixing of the frame are not high, resulting in uneven growth of plants at different locations, which seriously affects the production efficiency of the factory. In order to solve this problem, a high illumination uniformity plant light source and frame design scheme is proposed. The light source is "inverted" on the triangular prism bosses on both sides of the planting surface, and the prism slope is used to distribute light and improve the uniformity of the distribution. Further increasing the light mixing distance and improving the degree of light coupling, thereby the color mixing uniformity and illumination uniformity were imporoved. The proposed optical structure was simulated by TracePro software, and the experiment was carried out by Taguchi method. Finally, the influence degree of each factor was analyzed by ANOVA theory and the result was further optimized. The illumination uniformity of the final design reached 94.30%, and the color mixing uniformity reached 90%. Finally, by measuring the illuminance of the planting surface and the surface of the plant, whether the growth of the plant is obstructed by light was detected, the results show that the plant lighting system can maintain the planting surface and the top and side of the plant with good illumination during the growth process.关键词：plant light source;optical design;plant factory;light emitting diode;Taguchi177|263|4更新时间：2020-08-12
- 摘要：The failure location technology is an important component of the LED failure analysis. In this paper, based on three main failure positioning technologies, namely, emission microscope(EMMI), optical beam induced resistance change(OBIRCH), and infrared thermal imaging(THERMAL), a micro infrared hot spot location system is proposed. By bilinear interpolation algorithm to enlarge the system source image magnification four times, under the condition of using 20-micron micro-lens, the system can achieve the effect close to 5-micron micro-lens, reduce the cost of the LED failure inspection by using the superposition of visible image and infrared thermal image. The LED chip failure point can be locked by increasing the voltage, which can quickly locate the LED chip defect in a wide range. On this basis, by combining FIB technology and SEM equipment to analyze the microstructure of LED chip, the failure reason of LED chip can be further analyzed, and finally the failure mechanism of LED chip can be obtained. The experimental results show that in the initial defect location, the micro-infrared hot spot location system can quickly provide the thermal data distribution of LED in a large area under non-destructive conditions and locate the key failure points, effectively improve work efficiency and reduce the cost of failure detection.关键词：microscopic infrared hot spot location;light emitting diode;failure analysis;failure location;bilinear interpolation algorithm157|343|1更新时间：2020-08-12
- 摘要：The common optical filters at this stage mainly filter optical signals with specific wavelengths. When the bandwidth of the optical filter is narrow, it is very sensitive to the wavelength drift, which limits their application. The optical filter proposed in this article is based on an all-optical integrator composed of lens and multimode fiber(MMF). Based on its time domain characteristics, we analyze its frequency domain characteristics. This filter is used for optical carrier recovery to demonstrate its application. We verified the method by numerical simulation. The technology changes the intensity relationship between the two sides of the phase modulation signal and the carrier, it performs intensity modulation instead of phase modulation and the system didn't use the local oscillator laser during the modulation process.关键词：optical time domain filter;all-optical carrier recovery;temporal filtering;multimode fiber;all-optical integrator166|184|0更新时间：2020-08-12
- 摘要：Free-space coherent optical communication system using irradiance modulation(IM/CD) with dynamic detection threshold is proposed. Compared with traditional irradiance modulation and direct detection(IM/DD) systems, the system we proposed can detect the signal without requiring the knowledge of instantaneous channel state information(CSI) and the probability density function(pdf) of the turbulence model and achieve better average bit error rate(BER) just by only improving the LO power. Analytical expressions are derived for the average bit error rate of the system. Numerical studies show that the proposed system can achieve comparable performance to the idealized adaptive detection system, with a signal-to-noise ratio performance loss of only 1.4 dB at a BER of 10-9 for a lognormal turbulence channel with σ=0.25 and phase noise with σφ=0.07 when the local oscillator(LO) amplitude and transmitting amplitude are assumed to be unity.关键词：free-space optical communications;dynamic detection threshold;coherent detection167|313|0更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
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