GaN基蓝光发光二极管正向电压温度特性研究

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 关键词： 发光二极管 氮化镓 正向电压 温度系数

Temperature characteristics of the forward voltage of GaN based blue light emitting diodes

The temperature characteristics of the forward voltage of GaN based blue light emitting diodes are studied. We find that the temperature coefficient decreases with the increasing temperature when the temperatures is relatively high. There is an inflection point as the temperature coefficient deceases，then the temperature coefficient changes from negative to positive. If the temperature still increases at this moment，the forward voltage will increase dramatically，resulting in the failure of the light emitting diodes. This phenomenon is not obvious when the current is low. When the current increases，this phenomenon becomes more and more obvious，and the temperature of inflection point becomes lower and lower. Moreover, the forward voltage increases more quickly when the temperature is higher than the inflection point temperature. By comparing the test result of another group light emitting diodes with the same package epoxy, we find that the influence of glass transition temperature of the package epoxy can be neglected. The appearance of this phenomenon is due to the rapid increment of the equivalent series resistance，of which the main reason is the rapid deterioration of the p-type layers of the GaN based blue light emitting diode. The result shows that we can judge the quality of the GaN based blue light emitting diodes p-type layers quickly by measuring the variation of the forward voltage with temperature，which is a rapid method for the researchers and producers.