Improvement of Electrostatic Discharge Characteristics and Optical Properties of GaN-Based Light-Emitting Diodes

To improve the positive- and negative-voltage electrostatic discharge (ESD) characteristics of GaN light-emitting diodes (LEDs), an air gap was introduced as an ESD protection structure in an Al film on the bottom side of a sapphire substrate. The negative-voltage ESD characteristic of GaN LEDs with an air gap was remarkably improved from -0.3 to -4 kV. The degradation of electroluminescent intensity of GaN LEDs, which was caused by ESD stress, was also suppressed by an air gap in GaN LEDs. An ESD-stress-induced current is believed to flow in an air gap to protect the multiquantum well of GaN LEDs.