المؤلفون: Qiu-Wei Zheng, Yulin Gao, Zhong Chen, Yijun Lu, Tingzhu Wu, Ziquan Guo, Lihong Zhu, Yu-Jiao Ruan, Yue Lin, Weijie Guo

المصدر: IEEE Transactions on Instrumentation and Measurement. 70:1-7

مصطلحات موضوعية: Optical fiber, Materials science, business.industry, Photoelectric effect, medicine.disease_cause, law.invention, Acceleration, law, medicine, Optoelectronics, Junction temperature, Electrical and Electronic Engineering, business, Instrumentation, Remote control, Ultraviolet, Light-emitting diode, Diode

الوصف: Ultraviolet light-emitting diodes (UV LEDs) have been widely applied in various fields, such as sewage treatment, sterilization, and disinfection medical treatment. However, the remained problems of UV LEDs mainly concern poor photoelectric stability, low efficiency, safety protection, and among others. In order to evaluate and predict the stability and lifetime of UV LEDs safely and efficiently, a comprehensive UV LEDs two-step aging test system has been designed in this work. Two steps of different temperature stresses with total aging time up to 720 h are applied to UV LEDs. The junction temperature derived from spectroscopy has been taken under consideration during the test to evaluate lifetime accurately. A smartphone-based remote control and test scheme has been developed to monitor and control the online testing and therefore ensure the safety and convenience during the aging experiment.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::70c0bb30732fb16e36eb2d334fc147d9Test
https://doi.org/10.1109/tim.2021.3094627Test

المؤلفون: Yue Lin, Changwen Su, Zhangbao Peng, Hao Lu, Weijie Guo, Tingzhu Wu, Zhijie Ke, Zhong Chen, Yijun Lu

المصدر: IEEE Electron Device Letters. 40:1132-1135

مصطلحات موضوعية: 010302 applied physics, Materials science, business.industry, Current crowding, Substrate (electronics), Electroluminescence, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, law, 0103 physical sciences, Optoelectronics, Light emission, Electrical and Electronic Engineering, business, Current density, Microscale chemistry, Light-emitting diode, Diode

الوصف: Spatially resolved electroluminescence emitted through the sapphire substrate of GaN-based flip-chip green microscale light-emitting diodes with $20\times 20\,\,\mu \text{m}^{\text {2}}$ mesas has been collected via microscopic hyperspectral imaging. The current crowding is identified in the central region of the mesa, corresponding to the position of the p-pad. The bright-spot emissions at the edges of the mesa originate from localized potential energy valleys. This letter suggests that the comprehensive information about current crowding and the distribution of the light emission across the mesa of microscale light-emitting diode can be obtained by capturing spatially resolved light emission from the side of the transparent substrate.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::51d8b6d5c819de5887551a191222a90fTest
https://doi.org/10.1109/led.2019.2915023Test

المؤلفون: Yijun Lu, Yi Tu, Ziquan Guo, Lihong Zhu, Yue Lin, Yulin Gao, Tingzhu Wu, Honghui Zhu, Xiao Jingjing, Zhong Chen

المصدر: IEEE Transactions on Electron Devices. 64:2326-2329

مصطلحات موضوعية: 010302 applied physics, Materials science, business.industry, Thermal resistance, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Temperature measurement, Thermal management of high-power LEDs, Electronic, Optical and Magnetic Materials, law.invention, Amplitude, law, Thermocouple, 0103 physical sciences, Optoelectronics, Junction temperature, Electrical and Electronic Engineering, 0210 nano-technology, Alternating current, business, Diode

الوصف: We introduce a new method for measuring the junction temperature of alternating current light-emitting diodes. This method employs a periodic bipolar voltage pulse signal as the input, and utilizes the amplitude of corresponding output current as the temperature sensitive parameter (TSP), of which a linear temperature dependence is proven in a prior experiment in this paper. On the basis of the TSP, we devise a detailed procedure—first, measure the thermal resistance of the package of ac-LEDs, which further contributes to the calculation of junction temperatures under various power inputs. Comparisons between values calculated by using this method and those obtained directly from a thermocouple indicate a decent accuracy of the former. The advantage of this method benefits from the stability of thermal resistance under different driving conditions that one could immediately obtain the junction temperature by measuring the electric and optical powers.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::76f629dcda3426b979926ee406848042Test
https://doi.org/10.1109/ted.2017.2686704Test

المؤلفون: Yao Xiao, Lihong Zhu, Yulin Gao, Yijun Lu, Ziquan Guo, Tingzhu Wu, Sijia Dang, Yue Lin, Zhong Chen

المصدر: IEEE Transactions on Electron Devices. 64:2257-2260

مصطلحات موضوعية: 010302 applied physics, Optical fiber, Materials science, business.industry, Light extraction in LEDs, Dynamic range, 020208 electrical & electronic engineering, 02 engineering and technology, 01 natural sciences, Temperature measurement, Electronic, Optical and Magnetic Materials, law.invention, Optics, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Junction temperature, Electrical and Electronic Engineering, business, Absorption (electromagnetic radiation), Diode, Light-emitting diode

الوصف: Relative reflected intensity of the incident exciting light is proposed to measure the junction temperature of light-emitting diodes (LEDs) under test. Reflectance spectra at a wide junction temperature range are acquired. Multichannel optical fibers greatly increase the collecting efficiency of the reflected light. Lock-in technique is utilized to exclude the interference of the emitting light from LEDs under test and to increase the dynamic range greatly. The results are in good agreement with those directly tested by a microthermocouple. To avoid extra carrier absorption and modulation effect, the incident exciting light should harbor smaller bandgap than that of LEDs under test.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::2624c7030fb5d30768d7f8290ffa5667Test
https://doi.org/10.1109/ted.2017.2678513Test