人体模式静电对GaN基蓝光LED载流子运动及其可靠性的影响

对GaN基蓝光发光二极管(LED)分别施加-400,-800,-1 200,-1 500 V的反向人体模式静电打击,每次静电打击后,测量LED样品电学参数和光学参数的变化,从理论上分析了静电对LED可靠性的影响。实验发现:对GaN基蓝光LED进行人体模式下的静电打击后,其I-V特性曲线发生变形,光通量减小,老化时性能衰减的速率加快,这是由于受静电打击后在LED芯片内部产生了二次缺陷和熔融通道。对LED在不同温度下进行了I-V特性曲线的测量。实验结论认为未受静电打击的LED中浅能级离化占主导地位,受静电打击的LED中深能级离化占主导地位。静电引起的失效机理可以概述为二次缺陷和熔融通道的产生、深浅能级载流子的运动和辐射复合、非辐射复合之间的转变等因素引起的LED性能退化。

Effects of Human Body Mode Electrostatic on Carrier Movement and The Reliability of GaN-based Blue Light-emitting Diode

GaN-based blue light-emitting diodes were applied bias of-400,-800,-1 200 and-1 500 V electrostatic discharge in human body mode.The electrical and optical parameters of LED were characterized before and after electrostatic discharge stressing with the theoretical analysis of the influence of electrostatic on LED reliability.After human body mode static crack down on the GaN-based blue LED,the I-V characteristic curve changed,the luminous flux reduced,LED’s degradation rate was also accelerated.It is deduced that the LED was hit by electrostatic generates secondary defects and melting channel inside the chip.Based on the result of I-V characteristic curve at different temperature,we assumed that the shallow level ionization is dominated in LED,while after static crack down,the deep level ionization is dominant.Therefore,a failure mechanism caused by electrostatic can be deduced as follow.The generation of secondary defects and melting channel,the shallow level/deep level carrier movement and the change of radiative/non-radiative recombination,cause the degradation of LED performance.These find make great efforts to understand the failure mechanism caused by the electrostatic discharge and anti-static design.