Direct Evidence for Generation of Defect Centers during Forward-Bias Degradation of GaAs1−xPxElectroluminescent Diodes

Abstract

Direct evidence is presented for the generation of nonradiative defect centers in GaAs_1−xP_x electroluminescent diodes during forward‐bias degradation. The defect centers, which have been observed by thermally stimulated current measurements, have concentrations between 5×10¹⁴ and 6×10¹⁵ cm⁻³ and lie 0.2–0.4 eV from either band edge. A qualitative correlation is established between the concentration of the induced defect centers and the extent of the electroluminescence efficiency reduction. In contrast to irradiation‐induced defects previously described, defects due to long‐term operation cannot be removed by annealing. This difference in annealing behavior is discussed in terms of the nature of defects formed in each case.