GaN-based high electron mobility transistor (HEMT) has been widely used in satellite communication, space station and other fields due to its high thermal conductance, high breakdown voltage and radiation resistance. However, the existence of a large number of high-energy particles in space will induce defects in the device, resulting in the performance degradation or even failure of the device, which seriously threatens the reliability of the device.

This study aims to investigate the anti-proton irradiation damage ability of enhancement mode gallium nitride devices with different structures, analyze the degradation rule of the devices' electrical characteristics after proton irradiation, and clarify the damage mechanism of proton irradiation.

First of all, the enhancement mode Cascode structure devices manufactured by Transphorm corporation and P-GaN gate structure GaN HEMTs manufactured by Innoscience corporation were taken as irradiation samples. Then, a 5 MeV proton irradiation experiment with irradiation dose of 2×10¹² p?cm^-2, 1×10¹³ p?cm^-2, 1×10¹⁴ p?cm^-2 was carried out using the EN-18 serial electrostatic accelerator at Peking university for Cascode structure samples whilst only 1×10¹³ p?cm^-2 for P-GaN gate structure samples. The irradiation was carried out at room temperature, and the devices were not biased during the experiment. After each irradiation dose, drain current (I_ds), threshold voltage (V_th), and gate leakage current (I_gs) were electrically characterized in all the samples. Finally, Kesight B1500A semiconductor parameter tester and LFN-1000 low-frequency noise testing system were employed to test the electrical characteristics and low-frequency noise of these samples before and after irradiation.

The experimental results show that the threshold voltage negative drift of the Cascode device becomes more serious with the increase of proton irradiation dose, and the saturation drain current increases significantly. When the irradiation dose reaches 1×10¹³ p?cm^-2, the degradation of the electrical characteristics of the device begins to slow down. For P-GaN gate structure HEMT devices, the degradation law of electrical properties after irradiation is completely opposite to that of Cascode structure devices, and the degradation degree is significantly smaller than that of Cascode structure devices, indicating that Cascode structure devices are more sensitive to proton irradiation. Low-frequency noise test results show that the noise power spectral density of the device increases first and then tends to be stable with the increase of the irradiation dose, and its change law is consistent with the degradation of electrical characteristics.

Results of this study demonstrate that the ionization damage effect induced by 5 MeV proton irradiation produces more oxide trap charges and interfacial trap charges in the cascade Si MOSFET gate oxide layer of Cascode structure device, which is the main reason for its sensitivity to proton irradiation. This study provides a certain reference value for the reinforcement design of GaN power devices and the selection of aerospace devices.