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对小功率白光GaN基发光二极管(LED)在室温、40℃和70℃下进行温度加速老化寿命实验,通过对老化前后不同时间段器件的电学、光学和热学特性进行测量来分析器件的失效机理,着重分析器件的芯片和荧光粉的失效机理.器件老化前后的I-V特性表明:老化过程中,器件的串联电阻和低正向偏压下的隧道电流增大,这是由于器件工作时其芯片的欧姆接触退化和半导体材料的缺陷密度升高而引起的.器件的热特性表明:高温度应力下器件的热阻迅速变大,封装材料迅速退化,这是器件退化的主要原因;光谱曲线表明温度加速了器件的光功率衰减,并使荧光粉的转换效率迅速降低.最后使用阿伦尼斯方程对室温下器件的预测寿命进行了计算,并分析了GaN基白光LED的失效机理.
The experiments of temperature accelerated aging of low power white GaN based light emitting diodes (LEDs) at room temperature, 40 ℃ and 70 ℃ were carried out to analyze the failure mechanism of the devices by measuring the electrical, optical and thermal characteristics of the devices at different time before and after aging , Focusing on analysis of the device chip and phosphor failure mechanism before and after aging IV characteristics of the device shows that: the aging process, the series resistance of the device and the tunneling current under low forward bias increases, which is due to the device chip Of the ohmic contact degradation and the increase of the defect density of the semiconductor material caused by the thermal characteristics of the device shows that: under high temperature stress the thermal resistance of the device rapidly increases, the rapid degradation of the packaging material, which is the main reason for device degradation; spectral curve shows The temperature decayed the optical power of the device and the conversion efficiency of the phosphor decreased rapidly.At the end of this paper, the predicted lifetime of the device at room temperature was calculated by using the Arrhenius equation, and the failure mechanism of the GaN-based white LED was analyzed.