Direct evidence for the role of gold migration in the formation of dark-spot defects in 1.3-μm InP/InGaAsP light-emitting diodes

Abstract

The results of our previous study of dark-spot defects (DSD’s) in aged 1.3-μm InP/InGaAsP light-emitting diodes (LED’s) have strongly suggested that the defects form as a result of the migration of gold from the p contact into various epitaxial layers. To provide further support for this degradation mechanism, we compare, in this study, the formation of DSD’s in LED’s fabricated with the usual BeAu p metallization and a new platinum p contact. After accelerated aging (200 °C junction temperature, 20 kA/cm2, 3×103 h), DSD’s were observed only in the devices with BeAu contacts, thus directly identifying the active role of gold migration in DSD formation.