Reliability of deep-UV Light-Emitting Diodes

This paper analyzes the performance and reliability of deep-ultraviolet light-emitting diodes (LEDs) on AlGaN emitting at 280 and 295 nm. By means of detailed electroluminescence characterization, we show that the optical properties of the LEDs are strongly influenced by the presence of deep-level-related radiative transitions, and we separately evaluate the contribution of each of these recombination mechanisms on the overall light emission. The reliability analysis presented in this paper shows that stress determines the gradual decrease of the output power of the LEDs, which is more prominent at low measuring current levels. Degradation is attributed to the increase of the nonradiative recombination rate. By means of C-V analysis, we give evidence of modifications of the charge distribution in the active layer, taking place as a consequence of stress: this mechanism is considered to be related to the generation of new defect states near/within the active region.