Breakdown Mechanism And New Structure Of GaN Based Device

With the progress of science and technology,GaN materials have attracted a lot of attention and research all over the world due to their excellent properties.In this paper,we introduce the characteristics of GaN materials briefly,and the research progress and hotspots of GaN-based power diodes and HEMT are introduced.This paper summarizes the technical means adopted by scholars at home and abroad to improve the voltage withstanding.In order to solve the problem that the edge electric field lines of GaN-based PN junctions are concentrated and the electric field distribution in n-type semiconductor is not uniform enough,a GaN-based trapezoidal diode with high/low K composite dielectric layer is proposed.The structure can adjust the electric field inside the diode and make the electric field distribution more uniform.The simulation results show that the breakdown voltage of 4763 V can be achieved by a VCD-TGD diode composed of one layer of high K dielectric layer and two layers of low K dielectric layer.Compared with the common structure,the breakdown voltage of the device can be increased by 98%,the dynamic on-resistance Ron of the device is 5.22 m?·cm~2,the optimal power FOM is increased to 4.34GW/cm~2,and the reverse recovery time is 50 ns.In order to improve the electric field distribution in the channel of HEMT devices,a hybrid Schottky junction HEMT device is proposed.The new structure can adjust the electric field distribution in the channel more uniformly and greatly improve the breakdown voltage of the device.Compared with the field plate structure,no additional parasitic capacitance will be introduced,so that the frequency and switching characteristics of the device can be better guaranteed.The simulation results show that the breakdown voltage of the optimized device can reach 1105 V,which is 200%and 85%higher than that of the conventional structure and the field plate structure,respectively.The on-resistance is 0.53m?·cm~2,and the device's excellent value can reach 2.31GW/cm~2.