DEFECT CENTERS AND DEGRADATION OF GAP-N LEDS

A new degradation property of N-doped GaP light emitting diodes has been found. Diodes Zn-diffused through a thin layer of SiO2 exhibit a complete saturation of the degradation process at 70 to 80 % of the initial light output. After saturation of the degradation process the emission spectrum is broadened on the low energy side. This broadening is identified as due to the formation of additional nearest neighbour N-pairs during degradation. Diodes diffused without a SiO2 cover show neither a saturation of the degradation process nor a change of the emission spectrum. Deep level transient spectroscopy revealed different defect levels for the two types of diodes, therefore different degradation properties might be expected. © 1979 AIME.