Study On Ionizing Radiation Damage Law And Physical Mechanism Of GaN-based HEMT Devices

GaN is regarded as an ideal material for the preparation of power devices with high operating temperature,high operating frequency and high radiation resistance level due to its advantages of wide band-gap,high breakdown electric field,high electron mobility,high temperature resistance and radiation resistance.The total ionizing dose effect is an important factor restricting the long-term stable operation of GaN-based high electron mobility transistor?HEMT?devices in the space environment.As for Schottky HEMT devices,the current relevant research mainly analyzes the degradation mechanism of the devices from the experimental results,and lacks the corresponding numerical simulation research.In addition,to a large extent,Metal Oxide Semiconductor high electron mobility transistor?MOS-HEMT?devices overcome the problems of current collapse and severe gate leakage current in Schottky GaN HEMT devices,and have become a research object that has received much attention in recent years.However,there is little research on the total ionizing dose effect of AlGaN/GaN MOS-HEMT devices,and the main concern is the effect of irradiation on the DC parameters of the devices.Therefore,this paper established a simulation model of total dose ionizing irradiation for AlGaN/GaN HEMT devices,and analyzed the irradiation damage mechanism.On this basis,the depletion type AlGaN/GaN MOS-HEMT power devices were selected as the experimental research objects,using ⁶⁰Co?-ray radiation source to carry out the total dose ionizing irradiation experiment under different biases.The DC parameters and 1/f low-frequency noise test were used to characterize the DC parameters and defect density of the device under different biases before and after irradiation,and analyze the mechanism of the total dose ionizing irradiation effect of the devices.The main research contents are as follows:?1?A simulation model of total dose ionizing irradiation damage of AlGaN/GaN HEMT devices was established,and the mechanism of total dose ionizing irradiation damage of the devices was analyzed.The results showed that the oxide trap charge generated in the passivation layer by irradiation was not the main factor for device performance degradation,and the surface state induced by irradiation played a leading role in the degradation of devices performance.?2?The total dose ionizing effect on AlGaN/GaN metal-oxide semiconductor high-electron-mobility transistor?MOS-HEMT?devices after ⁶⁰Co?-ray irradiation with a total dose of 1 Mrad?Si?was investigated at different biases.The experimental results showed that under the condition of zero bias,the DC characteristic parameters of the devices are most deteriorated.?-ray irradiation induced oxide trapping charge inside the devices,they induce the depletion of electrons in the two-dimensional electron gas through induction,which reduces the density of the two-dimensional electron gas,which in turn leads to a reduction in saturation leakage current and maximum transconductance.?3?Based on Mc Whorter model of 1/f noise,the defect density in AlGaN/GaN MOS-HEMT devices before and after irradiation was extracted.The results show that the defect density increases by 60.28%after the device is irradiated under zero bias,which is significantly higher than the OFF state and the semi-ON state.The damage mechanism is the?-ray irradiation induces oxide defect charges in the oxide layer of the device,which increases the flat-band voltage noise power spectral density of the AlGaN/GaN MOS-HEMT device.Besides,the spatial distribution of the defects in the device before and after irradiation was obtained based on the charge tunneling mechanism.The change trend of the low-frequency noise test results is in good agreement with the DC test results.