Analysis of the physical processes responsible for the degradation of deep-ultraviolet light emitting diodes

This paper reports an extensive analysis of the degradation of deep-ultraviolet light-emitting diodes submitted to dc stress test. The study was carried out by means of combined electrical and optical characterization techniques. Results described in the paper indicate that the following: i stress can induce a significant decrease in the optical power emitted by the devices; ii optical power decrease is more prominent at low measuring current levels, thus suggesting that degradation is related to an increase in the concentration of defects; iii stress induces a significant increase in the green-yellow parasitic emission of the devices; and iv stress causes a localized increase in the apparent charge distribution profiles in the active region of the devices. Experimental evidence collected within this work suggest that degradation is due to an increase in the defectiveness in the active layer of the devices, with subsequent worsening of their radiative efficiency.