Design And Research Of High Voltage Fast Recovery Diode

With the rapid development of power electronic technology,power semiconductor devices as the core of power electronic technology,the demand for it is increasing.As the most common type of power semiconductor devices,power diode is mainly used for rectification and freewheeling in power electronic circuits.With the wide application of IGBT and power MOSFET in high frequency electrical,higher performance requirements are put forward for the power diode used together with them.Traditional Si Pi N Diode reverse Recovery performance is poor,in order to meet this demand,a power Diode called Fast Recovery Diode(FRD)which improves the reverse Recovery performance of Si Pi N Diode has been widely used.With the continuous iteration of diode technology,Si C JBS diode has a tendency to replace Si FRD in low voltage and high frequency applications due to its characteristics of low forward voltage drop and zero reverse recovery.These two types of devices can be summarized as two different technical routes of fast recovery diodes,namely,the new structure technology for anode injection efficiency control on traditional Si based devices and the new material technology using the advantages of Si C materials.In this thesis,a Si fast recovery diode with new anode structure is designed and optimized,and a high current Si C JBS diode is also designed and studied,and the reverse recovery characteristics of the two kinds of devices are compared.In this thesis,Si FRD is studied theoretically,and its reverse recovery characteristics are mainly studied.A P-buffer layer anode structure diode using emitter injection efficiency control technology was proposed.In order to verify the optimization effect of the new anode structure on diode characteristics,a FRD with basic Pi N structure was simulated and optimized as a comparison.By optimizing the width and doping concentration of p-region,a P-buffer layer anode structure diode was obtained.The final simulation results show that the reverse peak current is about 8.0A,reverse recovery time is about 37 ns,softness factor is 1.384 under the test conditions of reverse voltage 400 V,current change rate di/dt is 1000A/?s,forward current 30 A.In order to compare the performance difference between Si C diode and Si FRD,both theoretical and experimental research on Si C JBS diode are carried out,and the Si C JBS diode with 650V/50 A specification are designed and manufactured according to actual conditions.The relationship between the forward and reverse characteristics of Si C JBS diode and the width of P+ region and Schottky region are studied.Larger Schottky region width brings better forward characteristics,but also increases the reverse leakage current of the device,so it is necessary to optimize the design of these two parameters.The manufacturing processes of Si C JBS diode are introduced,and the Si C JBS diode products were tested,which meet the design requirements.In addition,the reverse recovery characteristics of Si C JBS diode and Si fast recovery diode are compared,and the advantages and disadvantages of both in various application environments are discussed.The results show that Si C JBS diode has better reverse recovery characteristics and advantages in high frequency applications.Infrared imaging experiment and power cycle experiment of Si C JBS diode were carried out.The actual temperature distribution observed by infrared imaging experiment is not uniform,and the reliability of Si C JBS diode is verified by power cycle experiment.Finally,the surge current of Si C JBS diode is tested,and the results show that the maximum surge capacity is 305 A.