Study On Electrical Characteristics And Reliability Of AlGaN/GaN HEMT Devices

The gallium nitride(GaN)semiconductor material has the characteristics of large forbidden band width,high electron mobility,high breakdown voltage,good heat resistance and excellent radiation resistance,and is an excellent material for making high-frequency,high-temperature and high-power devices.In recent years,the GaN-based HEMT device has become a hot research topic for electronic power components and has shown great application prospects.The large-scale application of the GaN-based HEMT device is limited because many of the reliability problems of the GaN-based HEMT device are not solved.Therefore,the reliability of the GaN-based HEMT device becomes the focus of the current research,and it is an urgent problem to be solved by the researchers.In this paper,the reliability of AlGaN/GaN HEMT devices in hydrogen effect,hot electron effect,electrostatic discharge and high temperature stress is studied.The variation of AlGaN/GaN HEMT devices under various stress conditions is studied by means of electrical characteristics and low frequency noise characteristics.The degradation modes and failure reasons of the devices are analyzed.The main research works of this paper are as follows:(1)According to the electrical characteristics and low-frequency noise characteristics of the AlGaN/GaN HEMT devices,the effect of hydrogen on AlGaN/GaN HEMT devices is studied.By comparing the device test parameters before and after hydrogen treatment,the action law of hydrogen treatment on the device is analyzed and summarized,and the action mechanism of hydrogen on the device is explained.On the one hand,after hydrogen treatment,the output current of the device is increases,the threshold voltage decreases,the negative drift,and the gate delay response is faster.On the other hand,hydrogen treatment can also reduce the current collapse of the device and reduce the average Hooge factor by half,which can effectively restrain the current collapse and reduce the noise of the device.(2)The hot electron effect of AlGaN/GaN HEMT device is investigated.The electrical properties of the devices before and after hydrogen treatment were compared by the electrical characteristics and low-frequency noise characteristics of the devices.The results show that under the action of hot electron stress,the output current of the hydrogen-treated device decreases,the threshold voltage increases,the threshold voltage moves forward,and the noise of the device increases.However,the performance of the device directly subjected to the hot-electron stress has no change.(3)The electrostatic discharge stress of AlGaN/GaN HEMT device is studied,and the transmission line pulse(Transmission Line Pulse,TLP)voltage is applied to the gate and drain of the device respectively.When the TLP voltage is lower than the breakdown voltage of the device,there is no change in the electrical characteristics.The photoluminescence image is not changed when the TLP stress device is observed by(Emission Microscope,EMMI)under low light-level microscope.When the TLP voltage is greater than the breakdown voltage of the device,the device fails and the gate leakage current increases.It is found that there is abnormal speckle in the photoluminescence image.The abnormal spot light is analyzed by scanning electron microscope(Scanning electron Microscope,SEM).The results show that TLP stress leads to gate fracture and its performance failure.(4)The high temperature reliability of AlGaN/GaN HEMT device is also investigated.The physical mechanism of the degradation of the device under high temperature stress is explored by simulating the high temperature environment of the electronic device in the constant temperature chamber.The DC characteristic,the output characteristic of the double pulse stress and the gate delay characteristic of the device at variable temperature are tested experimentally.The G-R(Generation-Recombination)noise of the device at different temperatures is also tested.The results show that under the action of high temperature stress,the output current characteristic of the device decreases with the increase of temperature,the transfer curve is slightly negative drift,the maximum transconductance decreases,the gate leakage current increases,and the delay response is faster.And at different temperatures,the trap activation energy of the original device is about 0.521 eV,after hydrogen treatment,and the trap activation energy of the device is about 0.552 eV.