对集成Ag基反射镜的垂直结构GaN基发光二极管(LED)薄膜芯片施加ESD(electro-static discharge)冲击,观察其静电失效的现象并对失效演变的过程进行研究。结果表明,LED芯片经过ESD冲击后,内部会随机出现ESD黑点。随着ESD电压逐渐增大,此ESD黑点逐渐演变成为静电孔。通过聚焦离子束刻蚀等手段,得出ESD黑点产生的原因,即静电击穿产生的瞬间高温将LED芯片中的p-GaN及Ag基反射镜熔化,从而使得Ag反射镜的反射率降低。在LED薄膜芯片静电失效的演变过程中,ESD黑点周围的GaN粗化面的六角锥结构出现形状变小、密度增大的现象,该现象与静电击穿发生的程度相关。因此,认为静电击穿过程中内部产生的瞬间高温对表面GaN材料的晶体质量产生较大影响。

Through electro-static discharge (ESD) strike, we investigate the electro-static discharge failure phenomenon and study the failure evolution process of a vertical structure GaN-based light emitting diode (LED) thin film chip integrated with Ag mirrors through electro-static discharge (ESD) strike. Results show that a black spot appears inside the chip subsequent to the application of ESD strike. With the increase of ESD voltage, the ESD black spot gradually develops into an electro-static hole. Based on the focused ion beam etching, the cause of ESD black spot is clarified as the reduction in the reflectivity of Ag mirrors occurring when the p-GaN and Ag mirrors in the LED chip are melted by the high temperature generated during the electro-static breakdown. During the electro-static failure evolution process of the LED thin film chip, the GaN coarsened hexagonal cone structure around the ESD black spot becomes smaller and denser. This is closely related to the degree of electro-static breakdown. Therefore, the high temperature generated by electro-static breakdown influences the crystal quality of surface GaN materials.