Degradation of InGaN-based MQW solar cells under 405 nm laser excitation
Résumé
Within this paper we analyze the reliability of 25 × multi quantum well InGaN-based devices, designed to be used as high power photodetectors or in multi-junction solar cells. Under stress with monochromatic excitation at 405 nm by means of a laser diode, we detect degradation at optical power levels significantly above the common AM1.5 spectrum; the main degradation modes are a reduction in short circuit current and in open circuit voltage, and an improvement in fill factor. The analysis of the wavelength-dependent EQE highlights, as a consequence of stress, the increase in concentration of a deep level compatible with the yellow luminescence in gallium nitride, suggesting that gallium vacancies may play a role in the degradation of the detectors.