Simulation Research On Optimal Design Of JBS Power Rectifier

With the development of power electronics technology,power semiconductor devices have received extensive attention and research as their core devices.The development of modern power rectifier devices such as power MOSFETs and IGBTs places higher demands on power diodes,and the performance of traditional power diodes such as PiN and Schottky urgently needs improvement.Junction barrier controlled Schottky(JBS)diodes have received widespread attention because of their fast characteristics and better reverse characteristics.This article discusses and studies the working principle and parameter optimization of JBS.In this paper,the structure and working principle of Schottky diode and JBS diode are analyzed theoretically.Based on an in-depth understanding of the working principle of JBS diodes,the initial structure models of silicon 50V and 4H-SIC 3000V JBS were established,and the Schottky diode and JBS diode were simulated and analyzed using silvaco simulation software,and compared with the theoretical analysis.To verify the correctness of the simulation method and the performance improvement of JBS diodes compared with Schottky diodes.Afterwards,the structural parameters of the two devices—different Schottky contact area and P~+junction depth—on the forward and blocking characteristics of the JBS diode were simulated and analyzed.With the increase of the area and junction depth of the P~+area of the JBS diode,the current conduction path changes,and the conductive area decreases,causing a slight decrease in the conductive characteristics.At the same time,due to the introduction of the two-dimensional electric field of the PN junction,the surface electric field of the Schottky region is reduced,which makes the reverse blocking characteristics of the JBS diode improved.With the increase of P~+area and junction depth,the reverse breakdown voltage has increased and the reverse leakage has been reduced.Based on the simulation analysis of the positive and negative characteristics,the optimization of silicon 50V and 4H-SIC 3000 V JBS diodes is given.Structural parameters:Under the premise of 1.25?m cell spacing,the optimal values of the contact width and junction depth of the P region of the silicon 50V JBS diode are 0.765?m and 0.9?m,respectively.The best values are 0.75?m and 1.2?m,respectively.When the junction depth of the P~+region extends close to the substrate,a super junction JBS structure is formed,and its reverse characteristics are greatly improved.Based on the analysis of the working principle of the super junction JBS diode,its structure was simulated,and the structural parameters of the P and N pillar regions were optimized.Under the condition that the junction depth and width of the P+region are 9?m and 0.75?m,and the width of the N pillar region is 0.5?m,the blocking voltage can reach 200V.The paper also simulates and analyzes the reverse recovery characteristics of JBS diodes,verifying that JBS still retains the characteristics of fast switching speed of Schottky diodes.Ordinary JBS diodes and super junction JBS diodes are unipolar power diodes developed on the basis of ordinary Schottky diodes.The introduction of PN junctions greatly improves the reverse characteristics of Schottky diodes.By optimizing the design structure parameters,the device has been comprehensively improved in three aspects:forward conduction,reverse blocking and reverse recovery.