Characterization of Green and Ultraviolet LEDs by Laser-Based FA Techniques

This work modifies existing nondestructive, laser-based techniques, such as thermally-induced voltage alteration (TIVA) and light-induced voltage alteration (LIVA), to determine precursors to failure in green and UV LEDs. Both TIVA and LIVA have been shown to be effective tools in localizing defects in Si-based integrated circuits and GaAs vertical cavity surface-emitting lasers. In a previous work, TIVA was also used to demonstrate failed InGaN LEDs in the III-V material system. This article expands the use of these techniques to localize potential precursors that lead to premature failures in deep green and deep UV LEDs. The paper shows how the TIVA/LIVA techniques were successfully used to characterize defects in wide bandgap AlGaN- and InGaN-based LEDs. The defects in the green LEDs appear to be electron-hole pair recombination sites and the observed voltage signals are primarily due to a LIVA effect.