Study On Damage Effect In GD4N24R Optocoupler Caused By Electron And Proton Irradiation

As a conversion device for electrical signals and optical signals,optocouplers are important devices widely used in spacecraft circuits.During its on-orbit service,the device will be significantly affected by the radiation environment of charged particles in space,resulting in degradation of its performance,which directly affects the high reliability of spacecraft in orbit.Therefore,exploring the radiation damage effect of optocoupler has important engineering practical significance and academic value.in this paper,the GD4N24 R optocoupler is taken as the research object.Based on the irradiation of low,high energy electrons and high energy protons,the electrical properties of the optocoupler are tested by the performance paramater tester of semiconductor devices.The deep level defect test and isothermal annealing test of the optocoupler after irradiation are carried out,and the key factors of the degradation of the electrical properties of the optocoupler and the damage mechanism under the irradiation of electrons and protons are explored.The experimental results show that the electrical properties of infrared light emitting diodes remain unchanged with the increase of irradiation fluence under 150 keV and 1 MeV electron irradiation conditions.When 150 keV electrons are irradiated,the electrical properties of phototransistors and optocouplers do not change much at low fluence.With the increase of irradiation fluence,the charge accumulation produces discharge phenomenon,which leads to the breakdown of phototransistors and the decrease of the overall performance of optocouplers.Under1 MeV electron irradiation,with the increase of irradiation flux,the base current of phototransistor increases,the collector current remains unchanged,the current gain decreases rapidly,the ideal factor approaches n=1,and the current transmission ratio of optocoupler decreases.Immersion hydrogen treatment before irradiation will aggravate the performance degradation of the radiation-induced phototransistor and optocoupler.Under the condition of 50 MeV proton and 90 MeV proton irradiation,the electrical property degradation characteristics of the optocoupler are basically the same.Under the same irradiation fluence,the electrical degradation of the device under 50 MeV proton irradiation is more serious..Under the proton irradiation conditions of the two energies,the electrical properties of the infrared light-emitting diodes remain basically unchanged.However,with the increase of irradiation fluence,the base current of the phototransistor increases remarkably,the collector current is basically unchanged,the current gain is gradually degraded,and the surface recombination mainly occurs in the neutral basal region.The current transfer ratio ofthe optocoupler decreases rapidly.Based on DLTS test and annealing test analysis,1 MeV electron irradiation will cause interface state traps and cascade defects in the phototransistor,resulting in a rapid decrease in current gain,which will reduce the overall performance of the optocoupler.The 50 MeV and 90 MeV proton irradiation caused the oxide positive charge and VP defect in the phototransistor,which caused the current gain to decrease,and the photoelectric coupling performance of the photoconductive adhesive decreased drastically,which togather led to the decline of the overall performance of the optocoupler.The protons of the two energies produce the same type of defects,so the damage to the phototransistor can be equivalent,and the types of defects generated by the electrons of the two energies are different,so the damage to the phototransistor cannot be equivalent.