Article
Chemistry, Physical
Do-Yeong Shin, Taehwan Kim, Ozgun Akyuz, Hilmi Volkan Demir, In-Hwan Lee
Summary: This study presents an improved efficiency design for white LEDs by integrating blue nanorod LEDs with green and red-emitting perovskite nanocrystal films. The design utilizes the localized surface plasmon effect of Ag@SiO2 nanoparticles to enhance the photoluminescence intensity of blue LEDs, while the high-power blue LED backlight improves the perovskite photoluminescence intensity. The resulting white LED with Ag@SiO2 nanoparticle-embedded nanorods demonstrates a 62% increase in photoluminescence intensity compared to planar white LEDs.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Optics
Shengjun Zhou, Zehong Wan, Yu Lei, Bin Tang, Guoyi Tao, Peng Du, Xiaoyu Zhao
Summary: This study proposes the use of InGaN quantum wells with gradually varying indium content to enhance the performance of GaN-based green LEDs. Experimental results demonstrate that green LEDs with gradually varying indium content exhibit higher light output power and lower efficiency droop.
Article
Optics
Hyun Jeong, Ga Hyun Cho, Mun Seok Jeong
Summary: We propose an efficient method to reduce efficiency droop in InGaN QWs by redistributing carrier localization through thermal annealing, resulting in increased internal quantum efficiency (IQE) in this study.
JOURNAL OF LUMINESCENCE
(2022)
Review
Materials Science, Multidisciplinary
Zhaojun Liu, Byung-Ryool Hyun, Yujia Sheng, Chun-Jung Lin, Mengyuan Changhu, Yonghong Lin, Chih-Hsiang Ho, Jr-Hau He, Hao-Chung Kuo
Summary: Micro-light-emitting diodes (Micro-LEDs) based on gallium nitride (GaN) materials offer versatile platforms for various applications, including displays, data communication tools, photodetectors, and sensors. By combining with quantum dots, Micro-LEDs can achieve efficient full-color displays and high-speed visible light communications.
ADVANCED MATERIALS TECHNOLOGIES
(2022)
Review
Crystallography
Panpan Li, Hongjian Li, Matthew S. Wong, Philip Chan, Yunxuan Yang, Haojun Zhang, Mike Iza, James S. Speck, Shuji Nakamura, Steven P. Denbaars
Summary: InGaN-based red micro-size light-emitting diodes (μLEDs) are highly attractive due to their less influenced external quantum efficiency (EQE) by size effect compared to common AlInGaP-based red μLEDs. Additionally, InGaN red μLEDs exhibit robust device performance even at high temperatures up to 400K. This review discusses the progress of InGaN red μLEDs and explores novel growth methods to relax the strain and increase the growth temperature of InGaN red quantum wells.
Article
Chemistry, Physical
Kyung Rock Son, Vignesh Murugadoss, Kyeong Heon Kim, Tae Geun Kim
Summary: This study investigates the effect of different passivation materials on the chemical bonds at the sidewall/passivation layer interface of μ-LEDs. The results show that the right passivation material can suppress non-radiative defects and enhance the light output power and current density of μ-LEDs.
APPLIED SURFACE SCIENCE
(2022)
Article
Engineering, Electrical & Electronic
Jiahao Yin, Xiaoshuai An, Liang Chen, Jing Li, Jianan Wu, Yumeng Luo, Qing Wang, Hongyu Yu, Kwai Hei Li
Summary: The study focused on monolithic integrated photodetectors (PDs) in InGaN/GaN LEDs for monitoring LED intensity fluctuations. Through simulation and experiments, it was found that placing the PD in the center of the LED resulted in a 58% increase in detected photocurrent with minimal impact on the LED emission profile compared to placing the PD at the edge. Encapsulating the LED-PD device with yellow phosphor enabled white light emission, and the on-chip PD showed similar sensing behaviors to an external Si-based photodiode. The optimal monolithic PD design offered comparable sensing capabilities, compactness, insensitivity to ambient lighting, and minimal influence on the LED emission profile, making it suitable for real-time monitoring of LED intensity in practical and scientific lighting applications.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Physical
Siyuan Cui, Guoyi Tao, Liyan Gong, Xiaoyu Zhao, Shengjun Zhou
Summary: This study reports the development of highly efficient indium gallium nitride (InGaN)-based yellow light-emitting diodes (LEDs) with low efficiency droop. By systematically engineering the indium composition in InGaN quantum barriers (QB), the researchers were able to improve electron confinement and suppress polarization field. This resulted in improved radiative recombination rates and reduced efficiency droop in the yellow LEDs. The study provides a feasible solution for high-performance InGaN-based LEDs in the long-wavelength spectral region.
Article
Optics
Longheng Qi, Peian Li, Xu Zhang, Ka Ming Wong, Kei May Lau
Summary: A prototype of full-color micro-LED micro-display with a pixel density of 391 ppi is demonstrated using InGaN/AlGaInP heterogeneous integration. This display shows the feasibility and prospects of high brightness, good color performance, and high-resolution micro-LED micro-displays in future metaverse applications.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Optics
Zhe Zhuang, Daisuke Iida, Martin Velazquez-Rizo, Kazuhiro Ohkawa
Summary: The study introduced a method for fabricating ultra-small InGaN μLEDs, successfully realizing different shapes of green μLEDs. It was found that as the size of the μLED decreases, the series resistance and turn-on voltage increase, while the light output power density and external quantum efficiency also improve.
Article
Materials Science, Multidisciplinary
Liwen Cheng, Xingyu Lin, Zhenwei Li, Da Yang, Jiayi Zhang, Jundi Wang, Jiarong Zhang, Yuru Jiang
Summary: InGaN LEDs with IGIT barriers have higher light output power, lower turn-on voltage, and less efficiency droop compared to LEDs with conventional GaN and InGaN barriers. These improvements are a result of the appropriately designed energy band diagram, which enhances hole injection efficiency and electron confinement.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Mohammad Hossein Alam Varzaneh Isfahani, Rahim Faez
Summary: A novel structure is proposed in this paper to decrease the polarization charges of quantum wells, aiming to improve the efficiency of light-emitting diodes and enhance radiative recombination rates. Energy bands diagram and carriers density are used to demonstrate the superior performance of the new structures, showing an increase in carriers injection in the new structures.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Wei Chen, Chuan Xu, Lingqing Kong, Xiang-Yang Liu, Xingye Zhang, Naibo Lin, Xinhua Ouyang
Summary: This study reports the use of silk fibroin (SF) as a flexible OLED substrate to improve device performance by enhancing light extraction efficiency (LEE). SF-based flexible OLED outperforms the reference device in terms of turn-on voltage, peak brightness, and LEE. The improved performance can be attributed to the low refractive index of SF, its lower surface roughness, and more matched energy levels compared to other substrates. Additionally, a molecular dipole layer formed between the interface of indium tin oxide (ITO) and SF effectively changes the ITO work function, reducing the potential barrier height for hole transfer.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Haotian Xue, Syed Ahmed Al Muyeed, Elia Palmese, Daniel Rogers, Renbo Song, Nelson Tansu, Jonathan J. Wierer
Summary: The recombination rates in red-emitting InGaN LEDs were studied to understand their efficiency limitations. The use of high Al-content AlyGa(1-y)N interlayers resulted in smoother surfaces and higher photoluminescence efficiency. IL-MQWs grown on SL-ULs showed lower A coefficients, indicating reduced defect formation. Compared to shorter wavelength InGaN-based LEDs, the B coefficients were significantly lower due to lower wavefunction overlap, while A and C coefficients were higher due to a higher number of defects.
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2023)
Review
Physics, Applied
Zhe Zhuang, Daisuke Iida, Kazuhiro Ohkawa
Summary: InGaN-based LEDs are efficient light sources in the blue-green range, but their efficiency decreases when extending to the red region, posing a challenge for integrating red, green, and blue LEDs for full-color micro-LED displays. This review summarizes the recent progress in InGaN-based red LEDs of various chip sizes, including epitaxial structures, device fabrication, and optical performance.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Construction & Building Technology
Jingxin Nie, Zhizhong Chen, Fei Jiao, Yifan Chen, Jinglin Zhan, Yiyong Chen, Zuojian Pan, Xiangning Kang, Yongzhi Wang, Qi Wang, Weimin Dang, Wentian Dong, Shuzhe Zhou, Xin Yu, Yuzhen Tong, Guoyi Zhang, Bo Shen
Summary: This study optimized the blue light hazard, luminous efficacy, and color rendering parameters of five-chip hybrid white LEDs using genetic algorithm. The results showed that the hybrid white light produced by the optimized LEDs had low blue light hazard and relatively high efficiency.
Article
Physics, Condensed Matter
Honghui Liu, Zhiwen Liang, Chaokun Yan, Yuebo Liu, Fengge Wang, Yanyan Xu, Junyu Shen, Zhengwen Xiao, Zhisheng Wu, Yang Liu, Qi Wang, Xinqiang Wang, Baijun Zhang
Summary: The AlGaN/GaN Schottky barrier diodes (SBDs) have great potential in the millimeter wave (MMW) field, but their application is limited by high reverse leakage current (J(r)). To overcome this limitation, a graded AlGaN/GaN heterostructure and recessed anode structure are introduced, resulting in significantly reduced J(r) and high cutoff frequency. These improvements make the SBDs more promising for future applications.
ADVANCES IN CONDENSED MATTER PHYSICS
(2022)
Article
Chemistry, Physical
Fabi Zhang, Jin Zhang, Lijie Huang, Shangfeng Liu, Wei Luo, Junjie Kang, Zhiwen Liang, Jiakang Cao, Chenhui Zhang, Qi Wang, Ye Yuan
Summary: In this study, epitaxial semipolar (11-22) AlN was successfully prepared on nonpolar m-sapphire substrate using sputtering and high-temperature annealing. The evolution of crystalline structure and morphology was investigated by measurements and analysis, showing that annealing improved the crystalline quality. The influence of AlN-sapphire interface on crystalline quality and lattice parameters during annealing was found to be less significant with increasing film thickness. The annealing duration had no effect on crystalline quality but had a noticeable impact on morphology, indicating that crystalline reorganization occurs before morphology reset. The zig-zag morphology of the AlN template along the sapphire [0001] direction, resulting from annealing, could affect the subsequent device epitaxy process.
Article
Chemistry, Physical
Jiahua Zhang, Hongsen He, Tongtong Zhang, Lingzhi Wang, Madhav Gupta, Jixiang Jing, Zhongqiang Wang, Qi Wang, Kwai Hei Li, Kenneth Kin-Yip Wong, Zhiqin Chu
Summary: In this paper, ultrasensitive all-optical nanothermometry using high figure-of-merit nanodiamonds with silicon-vacancy (SiV) centers is introduced. The two-photon approach is adopted to efficiently excite the SiV centers in nanodiamonds. With the developed intensity-projected scheme, a noise floor of 6.6 mK center dot Hz-1/2 is achieved experimentally, which sets a new record of temperature resolution in the relevant field. This simplified method allows reflecting the temperature-induced spectral shift without wavelength scanning via a spectrometer. Furthermore, the thermal activation of two-photon excitation of SiV centers is demonstrated.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Applied
Zhiwen Liang, Ye Yuan, Pengwei Wang, JunJie Kang, Qi Wang, Guoyi Zhang
Summary: This study comprehensively investigated the ex situ sputtered AlN buffer and GaN epilayer grown by metalorganic chemical vapor deposition. The study revealed that the AlN buffer deposited by sputtering technique could be oxidized in the atmosphere, which significantly affected the characteristics of the GaN epilayer. This finding has important guiding significance for the growth of high-quality III-nitride materials.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Mathematics, Applied
Qi Wang
Summary: The passage discusses the maximal and minimal values of the Hausdorff and packing dimensions of elements in the homogeneous product Moran sets determined by two sequences of positive integers {n(s)}, {m(s)} and two sequences of positive numbers {c(s)}, {d(s)}.
DYNAMICAL SYSTEMS-AN INTERNATIONAL JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Chuanyu Jia, Chunliang Shen, Qi Wang
Summary: The carrier-transport properties of InGaN red LED with V-pits layer and step-graded GaN barrier were investigated. The use of V-pits layer inhibits the lateral diffusion of electrons, improves the uniformity of holes concentration distribution, and reduces non-radiative recombination rate. The adoption of step gradient GaN barrier improves the injection efficiency of holes and alleviates the efficiency droop.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Multidisciplinary Sciences
Tongtong Zhang, Lingzhi Wang, Jing Wang, Zhongqiang Wang, Madhav Gupta, Xuyun Guo, Ye Zhu, Yau Chuen Yiu, Tony K. C. Hui, Yan Zhou, Can Li, Dangyuan Lei, Kwai Hei Li, Xinqiang Wang, Qi Wang, Lei Shao, Zhiqin Chu
Summary: The authors demonstrate the growth of robust and stable chaotic pattern of diamond microparticles containing SiV defects on silicon substrates. These microparticles can be used as anti-counterfeiting labels with high-capacity optical encoding and ultrahigh stability in extreme application scenarios. They can be practically applied in diverse fields immediately.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Mathematical
Wenjian Zheng, An Chang, Qi Wang, Jianing Shang, Mandi Cui
Summary: The correlation filtering algorithm is used to track dim and small targets in real time, improving accuracy. After denoising, a model is constructed using infrared small and weak target image data, and the brightness value and position of unknown targets are obtained. The joint probabilistic data association algorithm and particle filter are used for real-time tracking, achieving good accuracy. The algorithm reduces tracking deviation and is less affected by environmental factors.
ADVANCES IN MATHEMATICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Xixi Yin, Lang Zhou, Qi Wang, Yangfang Liao, Bing Lv
Summary: Using the first-principles method and Boltzmann transport theory, this paper systematically studies the electronic and phonon transport properties of two-dimensional TlInSe3. The results show that 2D TlInSe3 has excellent power factor and ultra-low lattice thermal conductivity due to low phonon group velocity and strong anharmonicity. Furthermore, the analysis reveals that 2D TlInSe3 exhibits a high ZT value as a potential TE material. These findings contribute to the exploration of new TE materials.
FRONTIERS IN PHYSICS
(2023)
Article
Physics, Applied
Li Zhang, Z. W. Liang, Q. Liu, A. L. Yang, Jun-Jie Shi, Qi Wang
Summary: In this work, a constraint relationship for the frequency and wave number of surface optical (SO) phonon-mode-assisted exciton photoluminescence (PL) is established using momentum and energy conservation laws. The dispersion relationships of SO modes in anisotropic wurtzite nanowires are used to determine the frequency and wave number of SO-mode-assisted exciton PL emission. This theoretical scheme and numerical results not only explain experimental discrepancies but also provide the potential for predicting and designing exciton PL spectroscopy in quasi-1-dimensional nanostructures with SO phonon modes.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Li Zhang, Qi Wang, Guang-Hui Wang
Summary: This paper investigates the dispersive spectra of polar optical phonon modes in III-nitride based nanostructures with different dielectric media using the macroscopic dielectric continuum model. The effects of dielectric and quantum size on the dispersive frequencies of phonon modes are emphasized. The study reveals that the dielectric constant of the inner/outer medium significantly influences the dispersive spectra of the surface optical (SO) phonon mode in GaN quantum rings (QRs), and the crystallographic structures of GaN also have different effects on the degenerating behavior and electron-phonon coupling strength. The findings provide a beneficial opportunity for independently adjusting the dispersive spectra of the two branches of SO modes in GaN nanostructures for the design and development of phonon-based detectors and sensors.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Zhen Huang, Renchun Tao, Duo Li, Zexing Yuan, Shanshan Sheng, Tao Wang, Tai Li, Zhaoying Chen, Ye Yuan, Junjie Kang, Zhiwen Liang, Qi Wang, Pengfei Tian, Bo Shen, Xinqiang Wang
Summary: In order to improve the performance of GaN-based green micro-light emitting diodes (mu-LEDs) array, a modular-architected p-type region is proposed, which consists of polarization-induced graded AlGaN and Al0.2Ga0.8N/GaN superlattices (SLs) to enhance p-type conductivity. The designed p-type structure exhibits a high hole concentration and excellent conductivity. The fabricated mu-LEDs array shows improved resistance, light output power, and data rate in comparison to devices with different p-type layers.
ADVANCED PHOTONICS RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Lang Zhou, Qi Wang, Mei Xu, Chengwei Hu, Xue Deng, Yumin Li, Bing Lv, Wenzhong Wang
Summary: In this paper, the TE properties of Tl2S3 were systematically studied using first-principles combined with Boltzmann transport theory. The results showed excellent power factor and ultra-low lattice thermal conductivity at room temperature. The ultra-low thermal conductivity of Tl2S3 was attributed to the lower phonon group velocity and larger phonon anharmonicity. Additionally, it was found that 2D Tl2S3 exhibited strong acoustic-optical scattering and a high ZT value at 400 K.
Article
Biochemistry & Molecular Biology
Jingxin Nie, Ningda Xu, Zhizhong Chen, Lvzhen Huang, Fei Jiao, Yiyong Chen, Zuojian Pan, Chuhan Deng, Haodong Zhang, Boyan Dong, Jiarui Li, Tianchang Tao, Xiangning Kang, Weihua Chen, Qi Wang, Yuzhen Tong, Mingwei Zhao, Guoyi Zhang, Bo Shen
Summary: With the increasing use of white light-emitting diodes (LEDs), the concern over blue-light hazard (BLH) has grown. In this study, a low-hazard light source was created by adding different wavelengths of light to a conventional phosphor-coated white LED. The results showed that the low-hazard light source caused significantly less damage to retinal function and photoreceptors, even with higher illuminance and blue-light hazard-weighted irradiance than the conventional white LED.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2023)
