Defect related issues in the “current roll-off” in InGaN based light emitting diodes

Defect related contributions to the reduction of the internal quantum efficiency of InGaN-based multiple quantum well light emitting diodes under high forward bias conditions are discussed. Screening of localization potentials for electrons is an important process to reduce the localization at high injection. The possible role of threading dislocations in inducing a parasitic tunneling current in the device is discussed. Phonon-assisted transport of holes via tunneling at defect sites along dislocations is suggested to be involved, leading to a nonradiative parasitic process enhanced by a local temperature rise at high injection.