Simulation Study on Optical Properties of GaN-based Blue LED

The optical properties of GaN-based blue light-emitting diodes(LEDs)are extremely important to study as these LEDs are utilized in a great many industries due to their excellent qualities,including high brightness,high energy efficiency,low energy consumption,and rapid reaction time.In this paper,Silvaco TCAD simulation software is used to do two-dimensional modeling and simulation of a GaN-based blue single quantum well vertical structure LED,with an emphasis on varied forward voltages,In components in InGaN,and quantum well thickness.The volt-ampere characteristic curve is compared and evaluated,as well as the energy band structure,carrier concentration,radiation recombination efficiency,electroluminescence spectrum,and internal current density distribution.The results show that when the forward voltage is 3.5V and the thickness of the quantum well is constant,the luminescence spectrum will show a red shift with the increase of the In content in the quantum well,and the luminescence spectrum will also show a red shift when the thickness of the quantum well is increased.However,when the quantum well thickness and In component are kept constant,the luminescence spectrum appears a red shift with increasing forward voltage.

31.38 Gb/s GaN-based LED array visible light communication system enhanced with V-pit and sidewall quantum well structure

Although the 5G wireless network has made significant advances,it is not enough to accommodate the rapidly rising requirement for broader bandwidth in post-5G and 6G eras.As a result,emerging technologies in higher frequencies including visible light communication(VLC),are becoming a hot topic.In particular,LED-based VLC is foreseen as a key enabler for achieving data rates at the Tb/s level in indoor scenarios using multi-color LED arrays with wavelength division multiplexing(WDM)technology.This paper proposes an optimized multi-color LED array chip for high-speed VLC systems.Its long-wavelength GaN-based LED units are remarkably enhanced by V-pit structure in their efficiency,especially in the“yellow gap”region,and it achieves significant improvement in data rate compared with earlier research.This work investigates the V-pit structure and tries to provide insight by introducing a new equivalent circuit model,which provides an explanation of the simulation and experiment results.In the final test using a laboratory communication system,the data rates of eight channels from short to long wavelength are 3.91 Gb/s,3.77 Gb/s,3.67 Gb/s,4.40 Gb/s,3.78 Gb/s,3.18 Gb/s,4.31 Gb/s,and 4.35 Gb/s(31.38 Gb/s in total),with advanced digital signal processing(DSP)techniques including digital equalization technique and bit-power loading discrete multitone(DMT)modulation format.

Aging mechanism of GaN-based yellow LEDs with V-pits

GaN-based yellow light-emitting diodes(LEDs) on Si substrates are aged at a direct current density of 50 A/cm^2 for500 h. After the aging process, it can be found that the LEDs have a stable electrical property but their light output power is decayed by 4.01% at 35 A/cm^2. Additionally, the aging mechanism of GaN-based yellow LED is analyzed. It is found that the decay of light output power may be attributed to the following two reasons: one is the increase of Shockley–Rrad–Hall recombination and the other is the change of the transport path of holes via V-pits after aging, which may induce the radiative recombination current to decrease. In this paper, not only the aging mechanism of GaN-based yellow LED is investigated, but also a new possible research direction in LED aging is given.

Optimization of a GaN-based irregular multiple quantum well structure for a dichromatic white LED

GaN-based irregular multiple quantum well （IMQW） structures assembled two different types of QWs emitting complementary wavelengths for dichromatic white light-emitting diodes （LEDs） are optimized in order to obtain near white light emissions. The hole distributions and spontaneous emission spectra of the IMQW structures are analysed in detail by fully considering the effects of strain, well-coupling, valence band-mixing and polarization effect through employing a newly developed theoretical model from the k. p theory. Several structure parameters such as well material component, well width, layout of the wells and the thickness of harrier between different types of QWs are employed to analyse how these parameters together with the polarization effect influence the electronic and the optical properties of IMQW structure. Numerical results show that uniform hole distributions in different types of QWs are obtained when the number of the QWs emitting blue light is two, the number of the QWs emitting yellow light is one and the barrier between different types of QWs is 8nm in thickness. The near white light emission is realized using GaN-based IMQW structure with appropriate design parameters and injection level.

Fabrication and Characterization of a GaN-Based 320×256 Micro-LED Array

Design, fabrication and characterizations of GaN-based blue micro light emitting diode （LED） arrays are reported. The GaN micro-LED array consists of 320×256 pixels with a pitch size of 30μm. Each pixel is 25×25μm^2 in size, which is designed for backside emission and high density flip-chip packaging. The selected LED pixels being tested exhibit good uniformity in terms of turn-on voltage and reverse leakage current. The efficiency droop behavior and reliability behavior under high forward current stress are also studied. The micro-LED pixel shows improved reliability, which is likely caused by enhanced heat dissipation.

Progress and prospects of GaN-based LEDs using nanostructures

Progress with GaN-based light emitting diodes （LEDs） that incorporate nanostructures is reviewed, especially the re- cent achievements in our research group. Nano-patterned sapphire substrates have been used to grow an A1N template layer for deep-ultraviolet （DUV） LEDs. One efficient surface nano-texturing technology, hemisphere-cones-hybrid nanostruc- tures, was employed to enhance the extraction efficiency of InGaN flip-chip LEDs. Hexagonal nanopyramid GaN-based LEDs have been fabricated and show electrically driven color modification and phosphor-free white light emission because of the linearly increased quantum well width and indium incorporation from the shell to the core. Based on the nanostruc- tures, we have also fabricated surface plasmon-enhanced nanoporous GaN-based green LEDs using AAO membrane as a mask. Benefitting from the strong lateral SP coupling as well as good electrical protection by a passivation layer, the EL intensity of an SP-enhanced nanoporous LED was significantly enhanced by 380%. Furthermore, nanostructures have been used for the growth of GaN LEDs on amorphous substrates, the fabrication of stretchable LEDs, and for increasing the 3-dB modulation bandwidth for visible light communication.

新型快速的 Blue-LED 快时间探测器标定系统

为了能够连续有规律地监测宇宙线广延大气簇射（ＥＡＳ）阵列快时间探测器和电子学系统各部分的性能随时间的变化，羊八井宇宙线ＥＡＳ实验使用了一套由ＣＡＭＡＣ－ＤＡＣ、ＴＫＯ－Ｂｕｆｅｒ、Ｂｌｕｅ－ＬＥＤ和ＬＥＤ－ａｍｐ构成的快时间探测器标定系统。该标定系统的速度快、易于扩展、引起的数据采集系统的死时间少，对于３０ＴｅＶ以上的空气簇射事例，羊八井二期阵列的角分辨可达０．５°，此外它还能监测光电倍增管周围温度的变化。

LED白光的亚甲蓝光化学法血浆病毒灭活研究

目的探讨LED白光的亚甲蓝光化学法对血浆中的病毒灭活效果。方法血浆中加入终浓度为1μM的亚甲蓝,以LED白光为光源,比较不同处理方式(10 cm/5 cm照射间距、单侧/双侧照射)、不同照射强度(30000 lx、35000 lx、40000 lx、45000 lx、50000 lx)和不同处理时间点(10 min、20 min、30 min)的血浆中凝血因子的活性及Sindbis病毒的灭活效果。结果在50000 lx照射强度下,随着照射时间的增加,血浆温度逐渐升高,升温幅度为5 cm间距>10 cm间距,双侧照射>单侧照射。5 cm/10 cm间距、单侧/双侧照射对凝血因子Ⅷ和纤维蛋白原(FIB)活性的影响均没有显著差异。以10 cm间距、双侧照射的处理方式作为病毒灭活装置条件参数,用30000 lx、35000 lx、40000 lx、45000 lx和50000 lx的光照强度分别照射5 min后,血浆中Sindbis病毒被灭活,滴度下降均>4 LogTCID50/0.1 mL;照射20 min后,血浆中凝血因子Ⅷ活性>70%、FIB活性>60%。光照强度与凝血因子损失的相关分析表明:不同的光照强度与凝血因子Ⅷ的活性损失没有相关性,光照的强度对FIB的影响表现在照射的20 min以内,照射强度越大FIB活性下降越严重,但照射30 min后不同的光照强度对FIB的影响已没有显著性差异。照射时间与凝血因子的损失高度相关,不同光照强度下凝血因子都随着照射时间的增加而损失。结论LED白光可以作为亚甲蓝病毒灭活方法的新光源,在合适的条件下有效灭活血浆中的病毒,并保留血浆中凝血因子的活性。

不同波长LEDs光源对苦荞芽菜生长、生物活性物积累及抗氧化活性的影响

为探究不同波长LEDs光源对苦荞芽菜生长的影响,本研究以黑暗(D)作对照,采用单色红(R)、蓝(B)、绿(G)光源培养苦荞芽菜,收获后分别测定其形态指标、生物活性物积累量、类黄酮合成关键基因表达量及抗氧化活性指标,结果表明:B处理的苦荞芽菜下胚轴呈深红色,伸长生长受到强烈抑制,花青素、总黄酮及总酚积累量均最高,分别是D的7.18、2.96和2.49倍;R处理的下胚轴呈浅粉色,上述3种生物活性物积累量分别是对照的2.56、1.68和1.40倍;G处理的下胚轴伸长与R相似,外观呈透明白色,生物活性物积累量与对照无显著差异。B和R均强烈诱导类黄酮生物合成通路上关键结构基因表达,显著增加苦荞芽菜下胚轴抗氧化活性。此外,各单色光处理均未显著影响苦荞芽菜可食用部位的鲜重。由此可见,红、蓝LEDs光源可显著影响苦荞芽菜形态生长,并增加其生物活性物积累及抗氧化能力,以蓝光最佳。

LED红蓝光配比对番茄生长和光合的影响

以番茄品种‘普罗旺斯’为材料,在双拱钢架日光温室内进行人工补光试验,设置T1(2R3B,即红光/蓝光珠数配比R:B=2:3)、T2(4R1B)、T3(6R1B)、T4(7R1B)四组红蓝光处理,以不进行人工补光为对照(CK),探究温室番茄生长和光合响应最优的红蓝光配比。结果表明,在T1处理下35d后,番茄的株高、SPAD、蒸腾速率(Tr)和光化学淬灭系数(qP)较对照组分别显著提高26.7%、19.6%、107.6%和34.3%。在T3处理下35d后,番茄的茎粗、花朵数、净光合速率(Pn)、胞间CO_(2)浓度(Ci)、气孔导度(Gs)、实际光化学效率(ΦPSⅡ)和电子传输速率(ETR)较对照组分别显著提高26.9%、38.6%、133.7%、5.9%、183.3%、31.3%和30.9%。在T4处理下35d后,最大光化学效率(Fv/Fm)较对照组分别显著提高4.0%。在对设施番茄进行不同配比红蓝光补光处理下,较对照组可显著促进番茄的生长及光合作用,在本试验设置的2R3B、4R1B、6R1B、7R1B四组红蓝组合光处理中,6R1B(红/蓝光珠数配比R:B=6:1)处理下各项指标表现的综合效果最佳,可为温室番茄栽培LED补光提供一定的理论指导。

Transcriptome analysis reveals effects of red and blue lightemitting diodes(LEDs)on the growth,chlorophyll fluorescence and endogenous plant hormones of potato(Solanum tuberosum L.)plantlets cultured in vitro

Red and blue light illumination has been reported to significantly affect plantlet growth.Potato is an important food and feed crop in the world and potato plantlet cultured in vitro plays an important role in potato production.However,few studies have documented the effects of red and blue light on the growth of potato plantlets revealed at the transcriptome level.The objective of this study was to determine the growth and physiological responses of potato plantlets cultured in vitro under monochromatic red(RR),monochromatic blue(BB)as well as combined red and blue(RB)LEDs using the RNA-Seq technique.In total,3150 and 814 differentially expressed genes(DEGs)were detected in potato plantlets under RR and BB,respectively,compared to RB(used as control).Compared to the control,the DEGs enriched in"photosynthesis"and"photosynthesis-antenna proteins"metabolic pathways were up-regulated and down-regulated by BB and RR,respectively,which might be responsible for the increases and decreases of maximum quantum yield(F_(v)/F_(m)),photochemical quantum yield(φ_(PSII)),photochemical quenching(q_(P))and electron transfer rate(ETR)in BB and RR,respectively.Potato plantlets exhibited dwarfed stems and extended leaves under BB,whereas elongated stems and small leaves were induced under RR.These dramatically altered plantlet phenotypes were associated with variable levels of endogenous plant hormones gibberellin(GAs),indoleacetic acid(IAA)and cytokinins(CKs),as assessed in stems and leaves of potato plantlets.In addition,monochromatic red and blue LEDs trigged the opposite expression profiles of DEGs identified in the"plant hormone signal transduction"metabolic pathway,which were closely related to the endogenous plant hormone levels in potato plantlets.Our results provide insights into the responses of potato plantlets cultured in vitro to red and blue LEDs at the transcriptomic level and may contribute to improvements in the micro-propagation of potato plantlets cultured in vitro from the light spectrum aspect.

Enhanced performance of GaN-based light-emitting diodes with InGaN/GaN superlattice barriers

GaN-based multiple quantum well light-emitting diodes （LEDs） with conventional and superlattice barriers have been investigated numerically. Simulation results demonstrate using InGaN/GaN superlattices as barriers can effectively enhance performances of the GaN-Based LEDs, mainly owing to the improvement of hole injection and transport among the MQW active region. Meanwhile, the improved electron capture decreases the electron leakage and alleviates the efficiency droop. The weak polarization field induced by the superlattice structure strengthens the intensity of the emission spectrum and leads to a blue-shift relative to the conventional one.

Optoelectronic Properties of GaN-Based Light-Emitting Diodes with Different Mesa Structures

GaN/InGaN lighting-emitting diodes with different mesa structures are studied. The current-voltage characteristics, light output power, luminous efficiency, and peak wavelength of the GaN/InGaN lighting-emitting diodes with different mesa patterns are compared. It shows that the current-voltage characteristics of the chips with more mesa areas are im- proved greatly by reducing the current crowding. With higher injection current the light output powers of GaN-based LED with more mesa areas are enhanced. And the chips with more P-electrode area have a smaller red shift and a little bit blue shift due to the reduction of the current crowding.

The Effects of Blue LED Light on Behavior and Retinal Function in Maternal and Offspring Mice

In the present study, we investigated whether blue light emission diode (LED) light exposure affects the maternal behavior of mice. The brain function of the offspring mice, including short-term memory, locomotor activity, anxiety-like behavior, and depression-like behavior, was evaluated. Pregnant mice at day 11 were housed in the apparatus for exposure to blue LED light during the daytime. Nesting behavior and the survival of pups were observed until weaning. After weaning, the offspring mice were bred in normal light conditions until 12 weeks old, and then the Y-maze test, open field test, and tail suspension test were performed. Retinal functions were evaluated by electroretinogram and histological analysis. Blue LED light exposure during the daytime induced retinal damage, but did not affect behavior related to maternal care in maternal mice. In the offspring mice, blue LED light exposure during the daytime did not affect the retina or brain functions. These findings suggest that blue LED light during the daytime might not be a risk factor for disruption of the mother-infant relationship or offspring brain development in mice.

低温流通过程中温度波动及LED蓝光对蓝莓品质的影响

为研究温度波动及LED蓝光对蓝莓低温流通过程中品质的影响,以黑暗处理为对照组,在LED蓝光条件下,设计波动次数为无波动,1,2次和3次以及不同断链时间(25,55 min和3 h)的温度波动处理组,比较分析冷断链时间下,温度波动对蓝莓品质指标和相关氧化酶的影响。结果表明:温度波动处理使蓝莓在贮藏期间的品质不断下降,相比于无波动组,波动3次处理的蓝莓在15 d时,硬度明显下降,可滴定酸、维生素C和花青素含量分别减少了60.49%,71.82%,42.27%,PPO、POD活性有所上升。与黑暗对照组相比,LED蓝光处理可有效延缓蓝莓营养物质的降解。此外,蓝莓对断链时间的忍耐程度各不相同,其品质下降的速率为:断链3 h>断链55 min>断链25 min。各指标间的相关性分析表明,硬度、维生素C和花青素呈显著相关(P<0.05),可用于评价蓝莓在低温流通过程的品质变化。结论:温度波动加剧了蓝莓果实品质劣变和营养成分流失,在尽量避免剧烈温度波动的同时,可考虑使用LED蓝光辐照,以改善蓝莓在流通过程中因温度波动而导致的品质下降。

Blue LED promotes the chemosensitivity of human hepatoma to Sorafenib by inducing DNA damage

Background:Phototherapies based on sunlight,infrared,ultraviolet,visible,and laser-based treatments present advantages like high curative effects,small invasion,and negligible adverse reactions in cancer treatment.We aimed to explore the potential therapeutic effects of blue light emitting diode(LED)in human hepatoma cells and decipher the underlying cellular and molecular mechanisms.Methods:Wound healing and transwell assays were employed to probe the inhibition of the invasion and migration of hepatocellular carcinoma cells in the presence of blue LED.The sphere-forming test was used to evaluate the effect of LED blue light irradiation on cancer stem cell properties.Immunofluorescence and western blotting were used to detect the changes inγ-H2AX.The Cell Counting Kit-8 assay,5-ethynyl-2′-deoxyuridine staining,and colony formation assay were used to detect the combined effect of blue LED and sorafenib on cell proliferation inhibition.Results:We demonstrated that the irradiation of blue LED light in hepatoma cells could lead to cell proliferation reduction along with the increase of cell apoptosis.Simultaneously,blue LED irradiation also markedly suppressed the migration and invasion ability of human hepatoma cells.Sphere formation analysis further revealed the decreased cancer stemness of hepatoma cells upon blue LED irradiation.Mechanistically,blue LED irradiation significantly promoted the expression of the phosphorylation of the core histone protein H2AX(γ-H2AX),a sensitive molecular marker of DNA damage.In addition,we found that the combined treatment of blue LED irradiation and sorafenib increased cancer cell sensitivity to sorafenib.Conclusion:Collectively,we demonstrated that blue LED irradiation exhibited anti-tumor effects on liver cancer cells by inducing DNA damage and could enhance chemosensitivity of cancer cells,which represents a potential approach for human hepatoma treatment.

具有高颜色表现能力与低蓝光危害的白光LED光谱优化

随着发光二极管的飞速发展,LED照明越来越多的被用于各个行业,且类似医疗、印刷、纺织、美容等行业对LED灯具的颜色表现能力要求很高;同时LED灯具带来的光生物危害也越来越被人们所重视,其中以LED蓝光危害最被人们所熟知。近年来很多研究者致力于如何降低白光LED的蓝光危害,但大部分工作都是在相对较低色温(CCT)的情况下获得需要的白光光谱,或者在一段色温范围内对进行离散穷举来找出最低蓝光危害的那一个相关色温对应的光谱;能够在不同的目标色温下获得同时拥有高颜色表现能力与低蓝光危害辐射的混合白光LED光谱几乎没有。为此,基于现有的多个LED提出了一种目标函数简单的非线性约束优化方法。在以往的研究中发现蓝光危害加权辐射通量与其相关色温呈现线性关系,随着其相关色温的增大,蓝光加权辐射通量也越来越大。要想获得具有低蓝光危害的白光LED光谱,只需固定其相关色温,就会得到每个目标相关色温对应的蓝光加权辐射通量,根据评价LED光源的蓝光危害辐射效率的计算公式,将其分子固定,只需最大化其分母,其蓝光危害辐射效率就会最小化,所以最大化辐射效率即可。针对其光谱功率分布,通过使用一个滤光片对被选择的多个LED混合后的光谱功率分布进行限制,同时因为实际生产需求要对滤光片的光谱透射率添加一个平滑约束,平滑约束则是使用加权平均的方法来完成。最后通过极大化“RP”方法得到各色LED的辐射量权重。仿真结果证明,该方法最终可以获得符合美国国家标准学会的ANSI/NEMA C78.377-2017标准的2700~6500 K八个目标相关色温,分别为2700、3000、3500、4000、4500、5000、5700和6500 K,各个CCT下的光源光谱其显色指数、色彩保真度、色域指数均在90以上,色偏差值在0.0054以内,蓝光危害辐射效率均在0.1以内的混合LED白光光谱。

不同色温LED补光对温室番茄幼苗质量的影响

秋冬或早春季节温室内光照不足会严重影响番茄幼苗的生长发育,因此,补光对温室番茄幼苗的培育显得尤为重要。本试验以“粉贝贝”为供试番茄品种,使用色温为3000 K、4000 K和6500 K的白色LED和红蓝(RB)LED进行补光,以不补光为对照(CK),研究不同色温LED补光光质对番茄幼苗生长、光合色素含量和生物量等质量指标的影响。结果表明:使用色温为3000 K、4000 K的白色LED补光能够显著增加番茄幼苗总叶面积,促进光合色素合成和生物量积累,同时显著抑制番茄幼苗下胚轴伸长。与CK相比,色温为3000 K的白色LED处理番茄幼苗的茎粗和总叶面积分别增加42.3%和121.6%,下胚轴长降低19.6%;色温为4000 K的白色LED处理番茄幼苗的叶绿素a、叶绿素b、类胡萝卜素含量和总叶绿素含量分别增加77.8%、61.7%、66.7%和73.6%。色温为3000 K和4000 K时,番茄幼苗的壮苗指数与CK相比增加141.0%和119.0%,但与RB无显著性差异。番茄幼苗的株高、总叶面积、光合色素含量、地上部干重和鲜重、总干重和总鲜重与补光光源中蓝光比例呈二次函数关系。综上看出,较低色温的白色LED可作为秋冬季节温室番茄幼苗培育的补光光源。

LED蓝光照射仪配合音乐抚触在新生儿黄疸患儿中的护理效果

目的:探讨LED蓝光照射仪配合音乐抚触在新生儿黄疸患儿中的护理效果。方法:选取2022年6月—2023年6月江南大学附属儿童医院接收的88例新生儿黄疸患儿,随机分为对照组与观察组,各44例。对照组给予LED蓝光照射仪治疗,观察组给予LED蓝光照射仪联合音乐抚触治疗。比较两组治疗前后的胆红素含量、依从性、康复时间及临床疗效。结果:观察组总依从性为97.73%,高于对照组的81.82%,差异有统计学意义(P<0.05);治疗前,两组总胆红素含量、经皮胆红素含量比较,差异无统计学意义(P>0.05),治疗后,观察组总胆红素含量、经皮胆红素含量均低于对照组,差异有统计学意义(P<0.05);观察组每日哭闹时间、黄疸消失时间短于对照组,每日睡眠时间长于对照组,差异有统计学意义(P<0.05);观察组总有效率为97.73%,高于对照组的79.55%,差异有统计学意义(P<0.05)。结论:LED蓝光照射仪配合音乐抚触治疗可降低新生儿黄疸患儿体内胆红素含量,缩短每日哭闹时间,延长每日睡眠时间,加快黄疸消失速度,从而提高临床疗效。

蓝光LD激发pc-WLED的发光性能

为了提升白光LED的光源亮度,同时降低LED效率骤降的影响,采用了蓝光LD激发pc-WLED的技术方案。研究了荧光陶瓷片与反射基板的关系,并分析了不同掺杂的荧光陶瓷片的性能。对荧光陶瓷片进行封装后,进行了性能比较。最后,将不同掺杂的荧光陶瓷片装配到RC激光模组中进行了对比实验。从结果可知,GaN基蓝光LED芯片是非常理想的反射基板,最适用于照明的荧光陶瓷为4xAl_(2)O_(3)+(Ce_(0.01)Y_(0.93)Gd_(0.06))_(3)Al_(5)O_(12),因为其氧化铝含量高,热导率好,且该荧光陶瓷不仅可以进一步提升白光LED的光源亮度,而且可以减小LED效率骤降的影响。