Study On Total Dose Effect Of GaN HEMT Device With Cascode Structure

As a typical third-generation semiconductor material,GaN material has excellent performance,and devices made from GaN material have also attracted much attention.The enhanced Cascode structure GaN HEMT device has great advantages in highfrequency,high-power,high-temperature and high-pressure applications,and has potential prospects in spacecraft deep space exploration.With the rapid development of China’s aerospace industry,the plan for Jupiter exploration has been put on the agenda,and there are a large number of high-throughput high-energy electrons in the orbit of Jupiter,and the impact of high-energy electrons on high-power GaN devices has attracted the attention of scholars at home and abroad.Based on the investigation of the structure and working principle of enhanced Cascode GaN HEMT,the highenergy electron and 60Co γ irradiation experiments have been carried out,meanwhile the mechanism of radiation damage on the device was investigated based on simulation.1)Electron irradiation of GaN HEMTs with enhanced Cascode structure.We first investigated the total dose effect of high-energy electrons on devices with energies of 10 MeV and doses of 5 Mrad(Si),20 Mrad(Si),50 Mrad(Si)and 80 Mrad(Si),respectively.The results show that the threshold voltage of the device is obviously negative drift and the drain current is obviously increased after irradiation.The threshold voltage offset of the device increases with the increase of irradiation dose.The reason of device performance degradation caused by electron irradiation was analyzed by Geant4 modeling and simulation.2)Study on the total dose effect of 60Co γ irradiation on enhanced Cascode GaN HEMTs.To investigate the effects of different total γ-irradiation doses on enhanced Cascode GaN HEMTs,we conducted a total dose effect study of 2 Mrad(Si)and 5 Mrad(Si)60Co γ-irradiation.The total dose effect caused by γ irradiation is more obvious than that caused by electron irradiation.The model of Si MOSFET in GaN HEMT with common source and common gate structure was established by using TCAD software,and the mechanism of total dose effect was analyzed.3)Comparison of irradiation effects for two different radiation sources on enhanced Cascode GaN HEMTs.We compare the annealing effect of different irradiation sources at the same time.It is found that the annealing effect of γ-irradiation is more obvious than that of electron irradiation.The comparison of the electric field intensity and electron hole concentration in the device under different irradiation sources shows that the electric field intensity and electron hole concentration in the device after y-irradiation are both greater than those after electron irradiation.