Influence of Built-in Electric Fields on the Gallium Phosphide- Based LEDs Hardness to Gamma-Ray Irradiation

Abstract

—The paper shows the influence of the power supply mode (without – ―M-B‖ and with the separation of electron-hole pairs – ―M-CC‖ generated by irradiation in the built-in electric field of the pn-junction of light-emitting diodes) on the LEDs emission power changing under gamma quanta. LEDs were based on monocrystalline gallium phosphide. The maximum radiation wavelength is at 655 nm. It is shown that the division of electron-hole pairs in the field of a built-in pn-junction makes it possible to significantly increase their stability. The emission power decreasing as a result of irradiation with gamma quanta is described in three stages. The first stage is due to the radiation-stimulated rearrangement of the first initial defect (complex of defects) of the first type. At the second stage, the decrease in power is due to the radiation-stimulated rearrangement of the initial defect (complex of defects) of the second type. In this case, the separation of electron-hole pairs generated during irradiation leads to a significant LEDs hardness increasing to the of gamma quanta action. At the third stage, the emission power decreasing is due to the only radiation defect’s introduction. For each of the identified stages of emission power reducing, empirical relationships, that describe the emission power changing with the radiation dose increasing and damage factors for the irradiation modes are numerically determined. Keywords— Radiation hardness, LEDs, GaP, gamma quanta, emission power