Degradation of high-efficiency Gap red LED's

The degradation of high-efficiency GaP red-light-emitting diodes has been studied by the observation of the changes in minority-carrier diffusion lengths, L
e
and L
h
, the Zn-O concentration, and the generated deep states in each stage of the degradation. The results have shown that the p-side degradation is followed by the n-side degradation. This degradation is dominated by the creation of deep centers responsible for the shortening of L
e
and L
h
. The decrease in the Zn-O concentration is less important in these high-efficiency diodes which have low Zn-O concentration and long initial diffusion lengths.