GaP Green LED Degradation Associated with P-Type Electrode Formation Process

Abstract

It has been clearly shown that the p-type electrode formation process has a great influence on the reliability of GaP: N green LED's. For Lot A, the occurrence of crystal defects during the sintering process was limited only beneath the electrode, and the relative values of η were as high as 91% after 1000 hour operation. For Lot B, however, the defects spread all over the p-type layer surface, and the relative values of were only 55%. The degradation in Lot B was attributed to the decrease in the minority-carrier lifetime in the p-type layer. As a model of the degradation mechanism, it was proposed that the defects associated with Ga vacancies were formed beneath the electrode and that they moved to the vicinity of the p-n junction.