Article
Physics, Applied
Ah Hyun Park, Seungjae Baek, Go Bong Choi, Yoong Ahm Kim, Jinsub Lim, Tae Hoon Seo
Summary: In this study, green light emitting diodes (LEDs) with Au nanoclusters in a micro-hole patterned p-GaN layer (ANCs-MHPP) were demonstrated to have higher internal quantum efficiencies and faster decay times compared to conventional green LEDs. The remarkable opto-electronic performance of green LEDs with ANCs-MHPP is attributed to exciton-surface plasmon coupling and surface texturing effect caused by the micro-hole patterned p-GaN layer.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Zhi-Wei Wen, Hong-Yi Lin, Mei-Jia Yang, Sen-Lin Li, Shuo Song, Shang-Feng Bao, Dong Sun
Summary: To improve the light extraction efficiency (LEE) of a plane AlGaAs-based LED (Device A), three different surface periodic micron-scale arrays were prepared using conventional UV lithography, including micron pillar (Device B), micron truncated cone (Device C), and micron cone (Device D). Scanning electron microscopy (SEM) was used to characterize the morphology of the three devices B-D. The periodic array structures increased the photon escape probabilities. Compared to Device A, the light output powers (LOPs) of Devices B-D increased by 54.0%, 145.5%, and 157.2% at an injection current of 500 mA, respectively. Additionally, Monte Carlo ray-tracing method was used to simulate the LEE of the four devices, showing that the energy distribution of Devices B-D was more concentrated in the middle region compared to Device A.
IEEE PHOTONICS JOURNAL
(2023)
Article
Physics, Applied
Xi Zheng, Xiyang Wu, Renlong Yang, Changdong Tong, Chenming Zhong, Fengyun Gao, Yue Lin, Guolong Chen, Yijun Lu, Zhong Chen, Weijie Guo
Summary: This study investigated the impact of mesa geometry on the light output characteristics of AlGaN-based DUV-LEDs. By dividing the original mesa into submesas and connecting them serially, significant enhancement of light output power and efficiency was achieved. Among the different submesas, hexagonal submesas showed the highest light output power and efficiency due to improved light extraction from the sidewalls. Additionally, pulse current driving was found to reduce the self-heating effect of the DUV-LEDs.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Po-Wei Chen, Po-Wen Hsiao, Hsuan-Jen Chen, Bo-Sheng Lee, Kai-Ping Chang, Chao-Chun Yen, Ray-Hua Horng, Dong-Sing Wuu
Summary: The mechanism of carrier recombination in downsized mu-LED chips was investigated, showing that the smallest chip size exhibited the highest ideality factor due to carrier recombination in high-defect-density zones. The use of a passivation layer and a maskless technology improved the performance and efficiency of the mu-LED chips. The blue-shift phenomenon in the electroluminescence spectrum was attributed to carrier screening and band filling effects, with high EQE values observed in the high current density region for the 10 x 10 μm(2) mu-LED chip.
SCIENTIFIC REPORTS
(2021)
Review
Nanoscience & Nanotechnology
Baodan Zhao, Maria Vasilopoulou, Azhar Fakharuddin, Feng Gao, Abd. Rashid Bin Mohd Yusoff, Richard H. Friend, Dawei Di
Summary: Perovskite light-emitting diodes (LEDs) have shown great potential for display and lighting applications with external quantum efficiencies exceeding 20% for various colors. However, the majority of internally generated photons are trapped in the devices and lose energy through lossy channels, suggesting the need for effective light management strategies. By analyzing the intrinsic optical properties of perovskite materials and the extrinsic properties related to device structures, this Review highlights the possibility of substantially exceeding the conventional limits of planar organic LED devices and suggests new approaches for achieving ultrahigh efficiencies in perovskite LEDs.
NATURE NANOTECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Guanding Mei, Xiangtian Xiao, Sajjad Ahmad, Hong Lin, Yangzhi Tan, Kai Wang, Xiao Wei Sun, Wallace C. H. Choy
Summary: This study demonstrates the importance of microcavity design for improving the light extraction efficiency of Perovskite light-emitting diodes (PeLEDs). The experiment shows that a high-efficiency horizontal dipole in the microcavity is the key to improving the efficiency.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Zhanxu Chen, Jialing Zhang, Runhong Ding, Feng Wu, An Wang, Guanghui Liu, Wei Wan
Summary: The study investigates the patterning of p-GaN and/or indium-tin-oxide (ITO) surfaces to improve light extraction efficiency for GaN-based LEDs. The results show that nanopillar-patterned p-GaN, ITO, and dual nanopillar-patterned p-GaN and ITO layers significantly enhance light output. The study also explores the mechanism of light extraction enhancement using 3D finite-difference time-domain method, and finds that LEDs with dual nanopillar-patterned p-GaN and ITO layers offer the best light extraction efficiency.
Article
Chemistry, Analytical
Xiu Zhang, Shuqi Li, Baoxing Wang, Baojin Chen, Haojie Guo, Rui Yue, Yong Cai
Summary: This study investigates a self-masking technology that roughens the surface of light-emitting diodes (LEDs) using a carbonized photoresist as a mask layer. By transferring the texture pattern of the mask layer to the surface of an Si3N4 passivation layer via reactive ion beam etching, LEDs with nano-textured surfaces were achieved. This self-masking surface roughening technology improved the efficiency of light extraction, resulting in higher wall-plug efficiency and external quantum efficiency compared to flat-surface LEDs.
Article
Chemistry, Multidisciplinary
Gai Zhang, Le Chang, Hua Shao, Chunshuang Chu, Chao Fan, Yandi Zhang, Yonghui Zhang, Zi-Hui Zhang
Summary: In this study, an ultra-thin air cavity nanopatterned sapphire substrate (UTAC-NPSS) is fabricated using a combination of nanosphere lens lithography, atomic layer deposition (ALD), and partial exposure lithography. The UTAC-NPSS improves the crystalline quality and light extraction efficiency (LEE) of GaN-based near-ultraviolet light-emitting diodes (NUV LEDs).
Review
Chemistry, Multidisciplinary
Bas Van der Zee, Yungui Li, Gert-Jan A. H. Wetzelaer, Paul W. M. Blom
Summary: The various contributions to the external quantum efficiency (EQE) of polymer light-emitting diodes (PLEDs) are discussed. It is found that the inclusion of triplet-triplet annihilation (TTA) contributes significantly to the enhancement of EQE in PLEDs.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Eun-Jeong Bae, Hyeong-Kyu Maeng, Ji-Soo Shin, Dong-Wook Park, Young-Wook Park, Dong-Hyun Baek
Summary: A micro-sphere PDMS film is proposed to improve the external quantum efficiency (EQE) in OLEDs. The film is fabricated through a specific process and the size and distribution of the micro-spheres play essential roles in improving the performance. Additionally, the film, based on polymeric materials, offers advantages in cost control and large-scale production.
Article
Chemistry, Analytical
Ruiqiang Xu, Qiushi Kang, Youwei Zhang, Xiaoli Zhang, Zihui Zhang
Summary: AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) have great potential in applications such as sterilization, UV phototherapy, and biological monitoring. Although they have advantages in energy conservation, environmental protection, and easy miniaturization, the efficiency of AlGaN-based DUV LEDs is still low compared to InGaN-based blue LEDs. This paper introduces the research background of DUV LEDs, summarizes various methods to improve the efficiency of DUV LED devices from three aspects: internal quantum efficiency (IQE), light extraction efficiency (LEE), and wall-plug efficiency (WPE). Finally, the future development of efficient AlGaN-based DUV LEDs is proposed.
Article
Optics
Zhihua Zheng, Qian Chen, Jiangnan Dai, Ange Wang, Renli Liang, Yi Zhang, Maocheng Shan, Feng Wu, Wei Zhang, Changqing Chen, Xiaohang Li
Summary: This study presents a packaging structure for double-layer nano-pattern arrays (NPAs) in AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs), which significantly enhances light extraction efficiency and device performance. The double-layer NPAs improve light output power by 28.3% compared to reference devices, demonstrating high peak external quantum efficiency and wall-plug efficiency. Finite element analysis confirms the higher external coupling efficiency of double-layer NPAs, making them an effective strategy for enhancing light extraction efficiency in UV devices.
OPTICS AND LASER TECHNOLOGY
(2021)
Review
Optics
Runnan Yu, Changxiao Li, Biao Zhao, Zhan'ao Tan
Summary: This work reviews the research history of green perovskite light-emitting diodes (GPeLEDs), introduces perovskites of different dimensions, and discusses the common synthesis methods of perovskites. Additionally, strategies to improve the stability and luminous efficiency of GPeLEDs are summarized, including component engineering, phase engineering, ligand engineering, additive engineering, interface engineering, and optical coupling structure strategy. Finally, the development state of GPeLEDs is summarized and future prospects are discussed.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Meng Tian, Huabin Yu, Muhammad Hunain Memon, Zhanyong Xing, Chen Huang, Hongfeng Jia, Haochen Zhang, Danhao Wang, Shi Fang, Haiding Sun
Summary: Micro-LEDs with smaller inclined chip sidewall angles exhibit improved external quantum efficiency due to stronger reflection of the inclined sidewall, leading to enhanced light extraction efficiency. The EQE improvement by adopting an inclined sidewall is more significant as the diameter of the LED chip reduces. Numerical optical modeling further verifies the impact of sidewall angles on the light extraction efficiency of micro-LEDs.
Article
Nanoscience & Nanotechnology
Charng-Gan Tu, Chia-Ying Su, Che-Hao Liao, Chieh Hsieh, Yu-Feng Yao, Hao-Tsung Chen, Chun-Han Lin, Chi-Ming Weng, Yean-Woei Kiang, C. C. Yang
Article
Optics
Yang Kuo, Wen-Yen Chang, Chun-Han Lin, C. C. Yang, Yean-Woei Kiang
Article
Optics
Yang Kuo, Chia-Ying Su, Chieh Hsieh, Wen-Yen Chang, Chu-An Huang, Yean-Woei Kiang, C. C. Yang
Article
Chemistry, Physical
Chia-Ying Su, Chun-Han Lin, Pei-Ying Shih, Chieh Hsieh, Yu-Feng Yao, Charng-Gan Tu, Hao-Tsung Chen, Horng-Shyang Chen, Yean-Woei Kiang, C. C. Yang
Article
Engineering, Electrical & Electronic
Chih-Hao Wang, Shin-Yi Ho, Jian Jang Huang
IEEE ELECTRON DEVICE LETTERS
(2016)
Article
Physics, Applied
Yu-Feng Yin, Wen-Yi Lan, Yen-Hsiang Hsu, Yuan-Fu Hsu, Chao-Hsin Wu, JianJang Huang
JOURNAL OF APPLIED PHYSICS
(2016)
Article
Nanoscience & Nanotechnology
Chih-Ken Chu, Yi-Chou Tu, Jen-Hung Hsiao, Jian-He Yu, Chih-Kang Yu, Shih-Yang Chen, Po-Hao Tseng, Shuai Chen, Yean-Woei Kiang, C. C. Yang
Article
Chemistry, Physical
Yu-Yang Liao, Yung-Tsan Chen, Chien-Chun Chen, Jian-Jang Huang
Review
Chemistry, Analytical
Yung-Tsan Chen, Ya-Chu Lee, Yao-Hsuan Lai, Jin-Chun Lim, Nien-Tsu Huang, Chih-Ting Lin, Jian-Jang Huang
Article
Chemistry, Analytical
Chi-Chung Chen, Yu-Ren Lin, Yu-Wei Lin, Yu-Cheng Su, Chung-Chi Chen, Ting-Chun Huang, Ping-Hsiu Wu, C. C. Yang, Shin Mou, Kent L. Averett
Summary: The study compares the p-type performance of Mg-doped/un-doped layer structures in AlGaN, showing that the layer-structured sample has lower sheet resistance and higher effective hole mobility due to hole diffusion from the Mg-doped layer into neighboring un-doped layers. Among the layer-structured samples, the 6/4 nm Mg-doped/un-doped thickness sample exhibits the lowest sheet resistance and highest effective hole mobility compared to uniformly doped samples.
Article
Biochemistry & Molecular Biology
Shaobo Yang, Po-Yu Chen, Chia-Chun Ni, Jun-Chen Chen, Zong-Han Li, Yang Kuo, Chih-Chung Yang, Ta-Cheng Hsu, Chi-Ling Lee
Summary: In this paper, the effects of surface plasmon coupling on the modulation responses of LED emission and down-converted lights through quantum dots are elaborated. The enhancement of modulation bandwidth through SP coupling is demonstrated. The results provide insights into the potential applications of SP coupling in improving the performance of LED-based light conversion.
Article
Chemistry, Physical
Kuntal Barman, Dai-Jie Lin, Rohit Gupta, Chih-Kang Chang, Jian-Jang Huang
Summary: This study proposes and simulates the design of a non-regrowth staircase channel GaN vertical trench transistor, showing excellent threshold and breakdown characteristics for high power and high frequency applications. The unique staircase design provides a variable capacitance through the gate-dielectric-semiconductor interface, resulting in a high breakdown voltage of 1.52 kV and a channel on-resistance of 2.61 m omega center dot cm(2). The variable length and doping profile in the channel region of this model offer greater flexibility to meet a wide range of device application requirements.
Article
Chemistry, Multidisciplinary
Shaobo Yang, His-Yu Feng, Yu-Sheng Lin, Wei-Cheng Chen, Yang Kuo, Chih-Chung Yang
Summary: In order to enhance color conversion from a quantum-well structure to a color-converting colloidal quantum dot, a device structure with quantum dots inserted into a GaN nano-porous structure was designed and implemented. Surface Ag nanoparticles were deposited to induce surface plasmon coupling with the quantum well structure. Experimental measurements and numerical simulations showed that the efficiency of Forster resonance energy transfer from quantum well to quantum dot was enhanced through this surface plasmon coupling, particularly for polarization perpendicular to the direction of the fabricated pores in the nano-porous structure.
Article
Chemistry, Multidisciplinary
Hao-Yu Hsieh, Ping-Wei Liou, Shaobo Yang, Wei-Cheng Chen, Li-Ping Liang, Yueh-Chi Lee, Chih-Chung (C. C. ) Yang
Summary: The high porosity of a GaN porous structure gives it mechanical semi-flexibility and the ability to shield against stress from thick growth templates. By analyzing the lattice constant variations, we investigated the effects of different strain-relaxation conditions on the growth of AlGaN on GaN templates. The fabrication of a strain-damping porous structure in the GaN template can reduce tensile strain in AlGaN and enable crack-free, thick overgrowth.
Article
Mathematics
Chang-Hua Lin, Shoeb Azam Farooqui, Hwa-Dong Liu, Jian-Jang Huang, Mohd Fahad
Summary: This article investigates a single-phase five-level T-type topology and applies the finite control set model predictive control (FCS-MPC) strategy to improve the performance and reliability of the system. The topology shows reliability, fault-tolerance, and high-quality output characteristics, making it suitable for renewable energy systems.
