Dynamic R_DSON Evaluation And Analysis Of E-mode GaN Power Devices

Semiconductor devices are the driving force for the development of power electronics.As an important representative of the third generation of semiconductor devices,gallium nitride(GaN)power devices,with tremendously enhanced performance,have broad application prospects and market opportunities in high-frequency,high-efficiency and high-power-density applications,such as data centers,new energy vehicles,distributed generation and consumer electronics,etc.However,due to charge trapping by the surface and buffer traps,the state-of-the-art GaN devices still suffer from dynamic on-state resistance(RDSON)degradation after switching from high-voltage off-state so far.It creates uncertainty to GaN-based converter design and loss estimation,and consequently has aroused extensive attention in academic and industrial communities in recent years.Previous works on dynamic RDSON evaluation of GaN power devices mainly focus on the test circuit design or the quantitative characterization under different operating conditions,such as operating voltage,current,temperature and frequency,etc.Most of the test methods can realize high-frequency and fast test,which match well with the practical applications.However,these works have some limitations:(1)The zero voltage switching techniques are widely used in high-frequency power conversion based on GaN devices.However,the test circuit widely used at present can only work under hard switching condition.(2)Currently,there are mainly two types of commercial single-chip normally-off GaN devices.The dynamic RDSON behaviors affected by different device structures under different switching conditions require in-depth investigation.For the above limitations,a dynamic RDSON test board integrating both hard and soft switching test circuits is built in this work.Two types of commercial GaN devices are tested and compared under hard and soft switching conditions by double-pulse and multi-pulse test modes,respectively.It has been found that with voltage stress up to 400 V and switching frequency up to 1 MHz,the dynamic RDSON of the two devices exhibit different behaviors under hard and soft switching conditions due to different device technologies,which should be taken fully into account for GaN-based converter design and loss estimation.Furthermore,the primary trapping mechanisms responsible for dynamic RDSON increase under different switching conditions are identified and verified by numerical device simulation using Silvaco TCAD tool.It reveals the limitation of the hole-inj ection-based dynamic RDSON suppression technology under soft-switching condition,which provides valuable information for the selection and evaluation of GaN power devices in practical applications.