Degradation of GaN LEDs by electron irradiation

Abstract

The degradation and recovery behavior of the device performance on GaN LEDs (light emitting diodes) irradiated by 2-MeV electrons and 70-MeV protons are studied. The reverse current increases after irradiation, while the capacitance decreases. The device performance degradation is proportional with the fluence. For electron irradiation, the fluence rate also has an impact on the degradation. A low fluence rate shows larger degradation compared to a high fluence rate due to heat impact in the bulk. DLTS measurements reveal the DX center in the substrate before and after irradiation, and the concentration of DX center increases with fluence. The radiation damage for protons is larger than that of electron irradiation, which is caused by the difference of mass and the possibility of nuclear collisions resulting in the formation of lattice defects. After irradiation, the diode performance recovers by thermal annealing.