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The influence of different degrees of high reverse-bias stress on high power light-emitting diodes (LEDs) was investigated based on the aging of LED devices under the stress of 85 °C / 85 % RH. GaN-based blue LEDs were respectively tested by negative Human-Body-Mode (HBM) electronic static discharge (ESD) at −1000 V, −2000 V, −3000 V, −4000 V and −5000 V. The electrical performances and optical performances...
GaN-based light-emitting diodes (LEDs) with Ga-doped ZnO (GZO) as current spreading layer was fabricated and investigated. At 350mA injection current, the light output power of GZO LED degraded 6% after 554 h under stress of 85°c/85%RH. We could see the current crowding effect appeared in GZO LEDs. The junction temperature of GZO LEDs became higher could exacerbate the devices. It was also can be...
Micro-grid can take the full advantages of the distributed renewable resources and improve the reliability of the power supply. The prerequisite is that the planned micro-grid itself should be well designed and its operation safety should be guaranteed. The intermittency characteristics of the Distributed Generators (DGs) could have negative impact on the reliability of the micro-grid. However, if...
Different materials and thickness of die-attach layers can directly affect the heat dissipation of LED devices, so the influencing mechanism of interconnect materials and thickness to the thermal performances and optical durability were studied respectively. In the experiments, chip-on-board LED devices interconnected by gold-tin(Au80Sn20), solder paste and silver paste were prepared and evaluated...
The reliability evaluation of Light Emitting Diodes (LED) is analyzed by lifetime test, which is usually derived from the accelerated test. In order to find the problem why the LED cannot reach the claimed lifetime, the reliability issue of the LED is investigated by the accelerated temperature tests. One of the accelerated test environment temperature is 55 °C and the environment is an oven, while...
Currently the development of large scale electric vehicles have become governments' focus of attention. Based on the research of charging and discharging power models, the paper puts forward the island formation strategy and establishes the distribution system reliability model with the electric vehicles. The Monte Carlo time sequential simulation is used to evaluate the effects of different vehicle...
With the rapid development of wind power generation, it is significant to study the impacts of wind farms on power system reliability. A general probabilistic model of a wind farm is proposed in this paper. The wind farm is modeled as a conventional unit with multiple states. The model could be used in conventional power system adequacy assessment utilizing analytical or simulation methods without...
High-power LEDs have been widely used and have a big potential market due to the many advantages compared to conventional light sources. Reliability is one of the most important issues for the application of LEDs. In order to study the degradation mechanism and the stability of LED withstanding cyclical exposures to temperature variations, life test was carried out under temperature cycle testing...
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