Defect generation in blue InGaN-based LEDs induced by proton irradiation

This paper reports on the degradation of two different series of commercially-available InGaN LEDs submitted to proton irradiation at 3 MeV. The degradation process was characterized by combined current-voltage (I-V), optical power-current (L-I) and capacitance-voltage (C-V) measurements, carried out before and after irradiation at 10^11, 10^12 and 10^13 p/cm^2. Results indicate that irradiation determines (i) a variation of the forward-bias characteristics of the diode; (ii) a spatially-uniform drop of the output optical power, detected only at the higher fluences; (iii) a decrease in junction capacitance. The experimental data suggest that radiation induced the creation of non-radiative centres in the active region of the LEDs, as pointed out by the good correlation between the variation of the ideality factor and of the junction charge identified on the irradiated samples.