The influence of γ-irradiation on the degradation of red-emitting GaP LED's

The effect of γ-irradiation on the degradation of p-GaP-n-GaP red light emitting diodes (LED's) is studied. It is shown that after the irradiation to a dose of 1.5 x 1017 γ/cm2 the LED's degrade, a decrease of red electroluminescence maximum (Λ = 0.675 μm, T = 77 K) by a factor of about 3 to 6 is observed. A following isochronal annealing of the irradiated diodes over the temperature interval from 100 to 300 0C leads to a partial recovery of the starting luminescence properties of the diodes. Similar effect is also observed when forward currents flow through the diode (j = 10-1 to 10-2 A/cm2) at temperatures 77 and 300 K. The data obtained are explained by defects (Frenkel type) which act as non-radiative centres. (author)