In situ measurements of atmospheric NO2 using incoherent broadband cavity-enhanced absorption spectroscopy with a blue light-emitting diode

We describe the application of incoherent broadband cavity-enhanced absorption spectroscopy(IBBCEAS) for in situ measurements of atmospheric NO2 using a blue light-emitting diode.The mirror reflectivity is determined by the transmitted intensity variation through the cavity caused by Rayleigh scattering.Concentrations of atmospheric NO2(1 to 35 ppbv) during the seven-day period are retrieved from the absorption spectra.The IBBCEAS measurement data are compared with those of a commercial long path differential optical absorption spectroscopy.The linear regression has a correlation coefficient and a slope     

Efficiency enhancement of an InGaN light-emitting diode with a p-AIGaN/GaN superlattice last quantum barrier

In this study, the efficiency droop of an InGaN light-emitting diode （LED） is reduced slgnlncanUy oy using a p-AlGaN/GaN superlattice last quantum barrier. The reduction in efficiency droop is mainly caused by the decrease of electron current leakage and the increase of hole injection efficiency, which is revealed by investigating the light currents, internal quantum efficiencies, energy band diagrams, carrier concentrations, carrier current densities, and radiative recombination efficiencies of three LED structures with the advanced physical model of semiconductor device （APSYS）.     

Advantages of an InGaN-based light emitting diode with a p-InGaN/p-GaN superlattice hole accumulation layer

P-InGaN/p-GaN superlattices (SLs) are developed for a hole accumulation layer (HAL) of a blue light emitting diode (LED). Free hole concentration as high as 2.6×1018 cm-3 is achieved by adjusting the Cp2Mg flow rate during the growth of p-InGaN/p-GaN SLs. The p-InGaN/p-GaN SLs with appropriate Cp 2 Mg flow rates are then incorporated between the multi-quantum well and AlGaN electron blocking layer as an HAL, which leads to the enhancement of light output power by 29% at 200 mA, compared with the traditional LED without such SL HAL. Meanwhile, the efficiency droop is also effectively alleviated in the LED with the SL HAL. The improved performance is attributed to the increased hole injection efficiency, and the reduced electron leakage by inserting the p-type SL HAL.     

Fabrication,properties, and applications of flexible magnetic films

Flexible magnetic devices, i.e., magnetic devices fabricated on flexible substrates, are very attractive in applications such as detection of magnetic field in an arbitrary surface, non-contact actuators, and microwave devices, due to their stretchable, biocompatible, light-weight, portable, and low cost properties. Flexible magnetic films are essential for the realization of various functionalities of flexible magnetic devices. To give a comprehensive understanding for flexible magnetic films and related devices, recent advances in the study of flexible magnetic films are reviewed, including fabrication methods, magnetic and transport properties of flexible magnetic films, and their applications in magnetic sensors, actuators, and microwave devices. Our aim is to foster a comprehensive understanding of these films and devices. Three typical methods have been introduced to prepare the flexible magnetic films, by deposition of magnetic films on flexible substrates, by a transfer and bonding approach or by including and then removing sacrificial layers. Stretching or bending the magnetic films is a good way to apply mechanical strain to them, so that magnetic anisotropy, exchange bias, coercivity, and magnetoresistance can be effectively manipulated. Finally, a series of examples is shown to demonstrate the great potential of flexible magnetic films for future applications.     

Improvement in electroluminescence performance of n-ZnO/Ga_2O_3 /p-GaN heterojunction light-emitting diodes

n-ZnO/p-GaN heterojunction light-emitting diodes with and without a Ga2O3 interlayer are fabricated. The electroluminescence （EL） spectrum of the n-ZnO/p-GaN displays a single blue emission at 430 nm originating from GaN, while the n-ZnO/Ga2O3/p-GaN exhibits a broad emission peak from ultraviolet to visible. The broadened EL spectra of n-ZnO/Ga2O3/p-GaN are probably ascribed to the radiative recombination in both the p-GaN and n-ZnO, due to the larger electron barrier （ΔEC=1.85 eV） at n-ZnO/Ga2O3 interface and the much smaller hole barrier （ΔEV=0.20 eV） at Ga2O3/p-GaN interface.     

令人振奋的LED光增强

发光二极管（LED）的发射效率可通过金属纳米结构来提高,因为金属纳米结构能增强发射光的方向性。AMOLFFOM研究所的GabrielLozano和JaimeG6mezRivas及其合作者已设计出了一种小型铝柱体,柱体表面的电子共振——被称为“表面等离子体共振”——能修正由白光LED发出的光,让光能以更可取的方式直接从柱体表面发射,     

酸溶法细径柔性传像光纤的制备及其表征

酸溶法传像光纤材料具有单丝直径细、柔软性能好、分辨率高等优点,在高清晰度光纤成像仪器和工业自动化检测等领域有着广阔的应用前景.本文从基质玻璃材料入手,开展了物化性能相互匹配的高光学质量预制棒管的制备、拉排丝以及硬质传像光纤的酸溶试验;对柔性传像光纤的分辨率、光谱透过率以及暗丝等进行了分析与表征.实验结果表明,该材料的制备过程突破了传统传像光纤的生产工艺,实现了传像光纤的结构与工艺创新.     

发光层掺杂对红光OLED性能影响研究

制备高效率、高亮度的红光有机发光二极管是显示器实现全彩色的关键,对高性能的红光有机发光二极管器件研究具有十分重要的意义.本文主要研究了掺杂剂(DCJTB)浓度对红光有机发光二极管性能影响.实验采用真空热蒸镀的方法,选取结构为ITO／2-TNATA(20 nm)/NPB(30 nm)/AlQ(50 nm):(X%)DCJTB／AlQ(30 nm)／LiF(0.8 nm)／Al(100 nm)的红光器件,在高准确度膜厚控制仪的监控下,实现了有机薄膜功能材料的精确蒸镀.研究表明:红光掺杂剂掺杂浓度为(2.5~3.0)%时,在12 V电压下,可以得到发光亮度最高达到8 900 cd/m²,发光效率大于2.8 cd/A,且发光光谱波长为610~618 nm较为理想的红光有机发光二极管器件.     

用于光通信的高速响应有机电致发光器件

采用直接光强调制的方法,建立了一种新型有机电致发光器件(OLED)的光电信号传输体系,研究了发光层掺杂、发光面积和预置电压对OLED响应速度的影响。结果发现:与发光层为单独的Alq3的器件相比较,掺杂rubrene的发光层的荧光寿命较短,响应较快;减小OLED的发光面积能提高OLED的响应速度,并在0.02 mm2的发光面积上实现了100 Mbit/s的信号传输速度;同时,预置直流电压也能改善OLED的响应速度。最后,提出将柔性OLED与聚合物波导及有机光电二极管结合,实现了一种全有机的柔性光电子体系。     

400nm高性能紫光LED的制作与表征(英文)

利用金属有机物化学气相沉积技术在蓝宝石衬底表面制备了带有p-AlGaN电子阻挡层的400 nm高性能紫光InGaN多量子阱发光二极管。制作了3种紫光LED,分别带有不同p-AlGaN电子阻挡层结构:Al摩尔分数为9%的p-AlGaN电子阻挡层;Al摩尔分数为11%的p-AlGaN电子阻挡层;Al摩尔分数为20%的10对p-AlGaN/GaN超晶格电子阻挡层。带有高浓度Al电子阻挡层的紫光LED的光输出功率高于低浓度Al电子阻挡层的紫光LED。带有10对p-AlGaN/GaN超晶格电子阻挡层的紫光LED的光输出功率获得了极大的提高,在20 mA注入电流时测试得到的光输出功率为21 mW。此外,该LED同时显示了在高注入电流下接近线性的I-L特性曲线和在LED芯片表面均匀的发光强度分布。