Trap And Degradation Of AlGaN/GaN HEMT On Stress

Ga N-based HEMT devices with high pressure,high temperature and anti-radiation and other characteristics,they are widely used in the field of power devices.Although the performance of Al Ga N / Ga N HEMT devices has reached a high level,its reliability is still one of the major problems which affects its wide application.Especially,in the high-voltage high-current operating conditions,the device performance will be gradually degraded,the essence is clear traps generated within the device.The existence of these traps,not only will cause the current collapse,the output power reduction and other issues,more serious is the impact of the device's long-term life.Based on this,the degradation of Al Ga N/Ga N HEMT devices under on-state stress is studied deeply in this paper.Through the software simulation,the influence of the defect on the degradation of the device is obtained.On this basis,combined with the experimental study,the main defects of the device degradation under open state stress are explored.In this paper,the influence of different defects on the device performance is studied.Using Sivalco simulation software,respectively,the HEMT device barrier layer,buffer layer of the trap to carry out the simulation work.The influence of the energy level,concentration and time constant on the degradation of electrical characteristics of HEMT devices was studied by changing the parameters.The simulation results show that applying a high voltage to the drain of the HEMT device under open conditions leads to the generation of hot carrier effects,which in turn causes degradation of the device.In addition,under the same conditions,the traps in the buffer layer have a greater impact on the electrical properties of the HEMT devices.The results further validate that the probability that the traps in the buffer layer are larger and the effect of the deep level trap on the current collapse of the HEMT device is greater than that of the shallow energy level.At the same time,the degradation of the device in the high field increases with the increase of the trap concentration,and decreases with the increase of the trap life.On this basis,the original on the sapphire substrate preparation of conventional depletion-type HEMT device carried out on-state stress experiment.In the experiment,the gate stress and the leakage stress were changed,and the electrical characteristics of the HEMT device were compared before and after the stress.The effects of different gate stress and leakage stress on the degradation of the HEMT device were studied.The experimental results show that under the condition of open state stress,the thermoelectron effect of HEMT device will lead to the decrease of saturated leakage current and the forward drift of threshold voltage.In addition,the degradation of the electrical characteristics of the HEMT device increases with the increase of the drain voltage,but increases firstly and then decreases as the gate voltage increases.Finally,based on the simulation and experimental results,it can be found that the main defects of Al Ga N/Ga N HEMT devices under open state stress are the deep defects in the device buffer layer.The results of this study can provide important technical guidance for the preparation of high reliability HEMT devices.