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对GaN基蓝光发光二极管(LED)正向电压温度特性进行了研究,发现在温度较高时,正向电压随温度的变化系数逐渐减小,直至出现拐点,正向电压随温度的变化系数由负数变为正数.此时若继续升高温度,则正向电压随温度升高迅速增加,并常常伴随有器件失效的现象发生.在小电流情况下,这种现象不很明显,随着电流的增加,现象表现得越来越明显,拐点出现的温度也越来越低,而且温度超过拐点之后,正向电压值增加得更快.通过与相同封装的另一组器件测试结果对比,排除了封装材料玻璃转换温度的影响.分析认为,这一现象的出现是由器件等效串联电阻迅速增加所致,而且主要是由器件p型层材料的迅速劣化引起的.研究结果表明通过测量不同电流下正向电压随温度的变化系数能够快速判断GaN基蓝光LEDp型层的质量好坏,为研究者和生产者提供了一种快速、简便的测试方法.
The research on the forward voltage and temperature characteristics of GaN-based blue light-emitting diode (LED) shows that at higher temperature, the coefficient of variation of forward voltage with temperature gradually decreases until the inflection point appears. The variation coefficient of forward voltage with temperature Negative numbers become positive. At this point, if the temperature continues to rise, the forward voltage increases rapidly with increasing temperature and is often accompanied by device failure. In the case of small currents, this phenomenon is less pronounced, with Current increases, the phenomenon becomes more and more obvious, the inflection point appears lower and lower temperatures, and the temperature exceeds the inflection point, the forward voltage increases more rapidly.With the same package of another set of device test results, The influence of the glass transition temperature of the package material is ruled out.The analysis shows that this phenomenon is caused by the rapid increase of the equivalent series resistance of the device and mainly caused by the rapid deterioration of the p-type material of the device.The results show that by measuring The variation coefficient of forward voltage with temperature at different currents can quickly judge the quality of GaN-based blue LED layer and provide a quick and easy test method for researchers and producers .