The role of nitrogen on the degradation behavior in LPE and VPE GaP:N light emitting diodes

Light output degradation of liquid-phase epitaxy (LPE) and vapor-phase epitaxy (VPE) GaP:N light emitting diodes (LED's) was studied by measuring electroluminescence efficiency, minority-carrier lifetimes, and effective nitrogen concentration during the degradation process. In LPE diodes the degradation is related to a decrease in minority-carrier lifetime, whereas in VPE diodes additionally a decrease in the effective nitrogen concentration was observed. This different degradation behavior is explained within a thermodynamic model which analyses the formation process of nitrogen atoms at substitutional and interstitial lattice sites under the different growth conditions of LPE and VPE.