Assessment of ESD robustness in high power light emitting diodes

The capability of high-power nitride-based light-emitting diodes (HPLED) to withstand electrostatic discharge (ESD) is very important key index due to the horizontal structure of the insulating property of the sapphire substrate. However, it is difficult to real-time monitor the damage caused by the ESD stress because it occurred in a very short period. Current-voltage (I-V) curves and electroluminescence (EL) spectrum were applied to study the change during the series ESD stress. Time-resolved optical beam induced current (TR-OBIC) was used to analyze the characteristics of the delay time between normal region and the defect point caused by ESD stress. Transmission electron microscopy (TEM) was used to compare to the difference in the distribution of damage region and investigate the failure modes. During the series ESD stresses, V-shaped pits suffered from the high electrical field and the distance from multi-quantum well (MQW). The bottom of V-shaped defect would be one of index to assess the ESD endurance of LED chips.