Degradation processes of 280 nm high power DUV LEDs: Impact on parasitic luminescence

With this work we report on characterization and reliability analysis of 280 nm high power commercial LEDs emitting 18 mW at 200 mA, with a peak wavelength of 280 nm. Spectral characterization reports the presence of a main emission peak and a sideband peak separated by 0.8 eV. DLTS analysis has also been carried out identifying two different defect traps, a deep level for electrons with E a = 0.73-0.92 eV and a shallow level for holes with E a = 0.18-0.28 eV. Results from constant current degradation tests report two different degradation mechanisms, a first degradation kinetic more noticeable at high current and a second more intense kinetic correlated to the increase of a third peak at higher wavelength. The work then suggests a reasoned interpretation by comparing the results with literature.