Research On Reliability Mechanism Of Algan/Gan Dynamic Switch

Gallium nitride materials have received extensive attention in the field of power semiconductors due to their advantages such as large band gap width,high critical breakdown electric field,and large electron saturation speed,and are regarded as the hope for the development of power electronic devices.Based on application requirements,major companies have successively developed a variety of technologies to implement enhanced GaN devices,and commercial devices have been put into use one after another.Therefore,it is of great significance to study the reliability of GaN devices in applications.This article focuses on the reliability of P-GaN enhanced commercial devices.The main work and innovations are as follows:First,the reliability of P-GaN devices under off-state high-pressure stress was studied.A stepped drain stress experiment different from other experiments is adopted.By changing the stress time and stress voltage value,the on-resistance and threshold voltage of P-GaN enhanced commercial devices are observed.The test results show that different devices behave differently under high-voltage stress in the off-state.When the high-voltage stress of 300 V is applied to the enhanced device without the P-GaN drain structure,the on-resistance degradation is the most severe,compared with the application of the 10 V off-state stress.The on-resistance is 17% higher,and the threshold voltage is hardly affected;the enhancement type device with the P-GaN drain structure has the most severe threshold voltage degradation at 50 V,which is reduced by 7%,and the change in the on-resistance is very The reasons for the small degradation are the trapping of electrons and the injection of holes.The application should consider different applications and select the corresponding device.Secondly,the reliability of P-GaN devices under long-term pulse conditions was studied.Through the simulation of commercial devices,the parameters of GaN operation are obtained.Using similar working conditions to the actual application of GaN devices,the GaN device is subjected to a long-term pulse stress test to simulate the state of the device working for a long time during the switching process.The most dramatic change after a long-term pulse stress test is the parameter of source-drain leakage current.Devices without a P-GaN drain structure have increased by more than ten times under a 1-hour high-voltage high-current pulse stress,and leakage paths have appeared in the area under the drain,because the gate leakage current of the device hardly changes,this leakage path appears at the drain,and the increase of the source-drain leakage current will have a great impact on the power consumption of the device.Other parameters measured in the article,such as on-resistance and threshold voltage,also showed more than 10% degradation.These degradations are due to the hot electron trapping effect and the hot electron trap effect,which can be restored after a period of time.The recoverable degradation in P-GaN devices is mainly due to the influence of electron traps,and the non-recoverable degradation mostly generates new traps.The overlap of the traps leads to the generation of leakage paths.