Electromigration-induced degradation around electrode of GaN light-emitting diode in water vapour

Reverse-bias operations for a light-emitting diode can quickly screen the weakness of the device. Electromigration around the electrode on the lateral and vertical directions can be observed by optical microscope images, scanning electron microscope images and energy dispersive spectroscopy. The failure process caused by the electromigration can be revealed by the changes of forward-bias and reverse-bias electroluminescence images and the emergence of the reverse-bias EL may be attributed to the diffusion of gold. Furthermore, the increase of the leakage current may supress the forward-bias band to band recombination current especially near the metal contact.