Impact of gamma-ray irradiation on photo emission from InGaN/GaN LED

The impact of gamma-irradiation on the unpacked InGaN/GaN LED properties has been studied. Before gamma irradiation exposure, three peaks located at 400, 447 and 568 nm were observed from room temperature photoluminence (PL) spectra, which were ascribed to InxGa1−xN (x = 0.11), InGaN/GaN multiple quantum wells and from (VGa–ON)2−/1−, respectively. Their peak positions remain unaffected for cumulative gamma-ray doses up to 100 kGy, but the PL intensities were changed with the gamma irradiation. The emission intensity from InGaN/GaN MQWs was firstly increased by 40 % with 30 kGy, the emission intensity from InxGa1−xN (x = 0.11) was decreased by one-third with a total dose of 30 kGy gamma irradiation and by two-third with 50 kGy. The LED properties showed that the operating voltage was increased with the total doses, the luminous flux and the photoelectric conversion efficiency were decreased with the total doses. The time-resolved photoluminence (TRPL) measurements showed that the lifetime prolonged gradually with the radiation doses.