Comparison And Analysis Of Short Circuit Capability Of 1200V SiC MOSFET And Si IGBT

Power semiconductor devices are the basis of power electronics and a key component of all power electronic systems.As a wide band gap semiconductor,silicon carbide(SiC)features higher critical electric field,higher saturation velocity,higher thermal conductivity.SiC power devices can be used in high voltage,high power,high frequency and high temperature applications.Commercial SiC power devices include silicon carbide diodes,silicon carbide metal-oxide-semiconductor field effect transistors(MOSFET),silicon carbide junction field effect transistors(JFET).Silicon carbide diodes have been used in renewable energy and railway fields.SiC MOSFET has also been used in the field of renewable energy.Compared with traditional Si IGBTs,SiC MOSFETs have the advantages of traditional Si IGBTs:high-speed switching performance,but also show higher breakdown voltage,lower on resistance and higher operating temperature.SiC MOSFETs is expected to replace Si IGBTs.However,there is some problems with SiC MOSFETs’ reliability due to the limitation of SiC MOSFET gate oxide process.If we want to achieve the widespread application of SiC MOSFETs,the reliability problem must be solved.Short circuit(SC)reliability is a kind of device reliability and refers to the ability to withstand high voltage and high current when the channel of the MOSFET is on.Despite intensive investigations on the short circuit capability of SiC MOSFETs and the mainstream Si IGBTs,a comparative study between the two types of devices are still missing to date.In this work,we have systematically compared and analyzed the SC capabilities of SiC MOSFETs(1200V/80mΩ,active area 8mm2)and Si IGBTs(1200V/25A,active area 20mm2).A test bench was designed.SiC MOSFETs are tested in different conditions and two failure modes are concluded from the experimental results.The index of SC capability is defined.Si IGBTs are also tested and the SC capability of SiC MOSFETs and Si IGBTs are compared.To provide in-depth understanding of the comparison results,1-D transient finite element thermal models of SiC MOSFETs and Si IGBTs have been implemented with simplified structures.We analyzed the difference in SC capability between the two devices through the simulated temperature profile.Finally,some suggestions on the reliability design of SiC MOSFETs are presented.