Combined optical and electrical analysis of AlGaN-based deep-UV LEDs reliability

This paper describes an analysis of the reliability of AlGaN-based deep-UV Light-Emitting Diodes (LEDs) emitting in the range 280-340 nm. LEDs have been aged at their nominal operating current, and during treatment their electrical and optical characteristics have been continuously monitored. Measurement results show that (i) constant current stress can induce degradation of the optical power emitted by the devices; (ii) degradation is more prominent at low measuring current level, thus suggesting that efficiency decrease is related to the generation of non-radiative paths; (iii) degradation does not imply a significant variation of the operating voltage of the devices, thus indicating that the characteristics of the ohmic contacts are stable over stress time; (iv) optical power decrease takes place together with modifications of the C-V apparent charge profiles, indicating that the generation of non-radiative paths is related to charge instabilities in the QW region.