Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Indium gallium nitride (InGaN) based blue light-emitting diodes (LEDs) suffer from insufficient crystal quality and serious efficiency droop in large forward current. In this paper, the InGaN-based blue LEDs are grown on sputtered aluminum nitride (AlN) films to improve the device light power and weaken the efficiency droop. The effects of oxygen flow rate on the sputtering of AlN films on sapphire and device performance of blue LEDs are studied in detail. The mechanism of external quantum efficiency improvement is related to the change of V-pits density in multiple quantum wells. The external quantum efficiency of 66% and 3-Voperating voltage are measured at a 40-mA forward current of with the optimal oxygen flow rate of 4 SCCM.
light-emitting diode (LED) sputtered aluminum nitride (AlN) physical vapor deposition (PVD) metalorganic chemical vapor deposition (MOCVD) Frontiers of Optoelectronics
2021, 14(4): 507–512
Author Affiliations
Abstract
1 School of Microelectronics, University of Science and Technology of China, Hefei 230026, China
2 Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92037, USA
3 Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
The AlGaN-based deep ultraviolet (DUV) light-emitting diode (LED) is an alternative DUV light source to replace traditional mercury-based lamps. However, the state-of-the-art DUV LEDs currently exhibit poor wall-plug efficiency and low light output power, which seriously hinder their commercialization. In this work, we design and report a tunnel-junction-cascaded (TJC) DUV LED, which enables multiple radiative recombinations within the active regions. Therefore, the light output power of the TJC-DUV LEDs is more than doubled compared to the conventional DUV LED. Correspondingly, the wall-plug efficiency of the TJC-DUV LED is also significantly boosted by 25% at 60 mA.
deep ultraviolet LED tunnel junction wall-plug efficiency AlGaN Chinese Optics Letters
2021, 19(8): 082503
1 华中科技大学 武汉光电国家研究中心，湖北 武汉 430074
2 中国科学院上海技术物理研究所，上海 200083
多量子阱红外探测器是一种新型的利用子带跃迁机制的探测器件，具有非常高的设计自由度。GaN/Al(Ga)N量子阱由于大的导带带阶，超快的电子驰豫时间，超宽的红外透明区域以及高的声子能量，使得其成为继GaAs量子阱红外探测器之后又一潜在的探测材料结构。文中详细综述了国内外关于GaN基量子阱红外子带吸收及其探测器件的研究进展。首先介绍了量子阱红外探测器的工作原理及其选择定则，接着从极性GaN基多量子阱、非极性或半极性GaN基多量子阱以及纳米线结构GaN基多量子阱三个方面回顾当前GaN基多量子阱红外吸收的一些重要研究进展，包括了从近红外到远红外甚至太赫兹波段范围的各种突破。最后回顾了GaN基多量子阱红外探测器件的研究进展，包括其光电响应特性和高频响应特性，并对其未来的发展进行总结和展望。
GaN 量子阱 红外探测器 子带跃迁吸收 GaN quantum well infrared photodetector intersubband transition absorption 红外与激光工程
2021, 50(1): 20211020
1 Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
2 Key Laboratory for Optoelectronics and Communication of Jiangxi Province, Jiangxi Science and Technology Normal University, Nanchang 330013, China
3 State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 110623, China
4 University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, China
Frontiers of Optoelectronics
2020, 13(4): 409
华中科技大学,武汉光电国家研究中心，武汉 430074
深紫外光源在杀菌消毒、生化检测、紫外固化、紫外通信等方面具有巨大的应用前景，基于AlGaN半导体的深紫外发光二极管(LED)因具有无毒、体积小、能耗低、寿命长、波长可调等优势，得到了广泛的关注和研究。经过近二十年的研究开发，AlGaN基深紫外LED无论是发光效率和器件寿命都得到了巨大的提升，已逐步开始商业化。然而，相对于GaN基蓝光LED，目前AlGaN基深紫外LED的效率仍旧非常低，还有很大的提升空间。本文首先介绍了深紫外LED的发展现状，并分析了导致器件效率低的原因。然后，分别从内量子效率、光提取效率以及电光转换效率三个方面对目前AlGaN基深紫外LED的研究状况进行了系统的回顾，总结了目前提高发光效率的各种手段和方法。最后对AlGaN基深紫外LED的未来发展进行了展望。
深紫外LED 内量子效率 光提取效率 电光转换效率 AlGaN AlGaN deep ultraviolet light emitting diode internal quantum efficiency light extraction efficiency wallplug efficiency
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Frontiers of Optoelectronics
2017, 10(4): 363
1 Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
2 School of Physics and Information Engineering, Jianghan University, Wuhan 430056, China
In this paper, Bi2S3 nanorods were successfully synthesized via a facile one-pot hydrothermal method and characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Then the Bi2S3 nanorods were deposited on Au interdigital electrodes by dip-coating to fabricate photodetectors. The photoresponse properties using Bi2S3 nanorods as a representative system showed a significantly enhanced conductivity and the current-voltage (I-V) characteristic exhibited about ca. 2 orders of magnitude larger than the dark current. The response and decay time was estimated to be ~371.66 and 386 ms, respectively, indicating Bi2S3 may be an excellent candidate for high speed and high-sensitivity photoelectrical switches and light sensitive devices.
Bi2S3 Bi2S3 nanorods nanorods photoresponse property photoresponse property photodetector photodetector Frontiers of Optoelectronics
2015, 8(3): 282
1 华中科技大学光学与电子信息学院武汉光电国家实验室, 湖北 武汉 430074
2 中国科学院上海技术物理研究所红外物理国家重点实验室, 上海 200083
通过结合电磁波在周期性纳米材料中的传播特性以及阿贝完备成像理论中的阿贝正弦条件，提出了一种快速测试光子等频图和能带结构的测试技术和光学检测系统。将无限筒长显微物镜作为一种把波矢空间直接转换到实空间的变换器件,并通过配备二维面阵CCD的光栅光谱仪实现了对周期性纳米材料的等频图和能带结构的一次性拍照，真正实现了方便、快速和无损的探测技术。利用自行搭建的测试系统对用自组装方法制备的二维周期性纳米材料进行了相关光学测试，通过实验测试结果和相关理论计算的对比验证了系统的可行性和可靠性，从而说明该光学系统在研究周期性纳米材料的光学特性方面具有一定的优势。
测量 光子晶体 阿贝正弦条件 光子等频图 光学学报
2014, 34(12): 1212004
中南大学湘雅医院放射科, 湖南 长沙 410008
为了探讨3D动脉自旋标记 (arterial spin labeling, ASL)技术对急性创伤性脑损伤(traumatic brain injury, TBI)病人的诊断价值, 将43例急性轻度TBI患者和20例健康志愿者进行了常规MRI(magnetic resonance imaging)和3D ASL扫描。结果表明,3D ASL能显示常规MRI所不能显示的脑内血流灌注情况。3D ASL结果发现, 健康志愿者组双侧前、中、后动脉供血区的脑血流量(cerebral brain flow, CBF)值比较均无差异(P值均＞0.05); TBI患者未出现明显低灌注区的脑实质CBF较志愿者脑实质CBF值明显降低(P值＜0.01); TBI患者脑内局部低灌注区较对侧镜面区的CBF值明显减低(P值＜0.01)。3D ASL技术能检测出急性轻度TBI患者脑实质灌注减低情况, 对于临床诊治有重要意义, 值得在临床推崇。
磁共振成像 动脉自旋标记 创伤性脑损伤 脑血管痉挛 脑缺血 magnetic resonance imaging arterial spin labeling traumatic brain injury cerebral vasospasm cerebral ischemia
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Frontiers of Optoelectronics
2013, 6(4): 429
