Research On GaN HEMT With A Surface Superjunction With Dual Doped Regions

As a third-generation semiconductor material,GaN has a high breakdown field and excellent heat resistance.As a III-V nitride,the internal polarization effect generates a built-in electric field at the interface of Al GaN and GaN,resulting in a high concentration and high mobility two-dimensional electron gas.Power devices manufactured based on GaN have higher saturation current and better frequency characteristics,which is a research hotspot.To further develop the advantages of GaN HEMTs,researchers have developed various voltage-resistant technologies.Among them,the lateral surface superjunction technology has great potential.This structure ensures high breakdown voltage of the device,reduces the difficulty of superjunction preparation process,reduces the coverage area of the voltage-resistant structure on the drift region,has smaller parasitic capacitance,and better high-frequency characteristics.By analyzing the breakdown mechanism of GaN HEMTs with transverse surface superjunctions,a novel surface superjunction with dual doped regions was proposed,which can further optimize the electric field distribution while retaining the advantages of transverse surface superjunctions.This thesis presents a comparative study of GaN HEMTs with conventional polarized superjunction,conventional lateral surface superjunction,and lateral surface superjunction with dual doped regions using Sentaurus TCAD software for threedimensional device structure modeling and simulation.The study found that,under the condition of a gate-to-drain spacing of 15 μm,a gate length of 1 μm,a superjunction length of 8 μm,and similar output characteristics,the parasitic capacitance of the lateral surface superjunction GaN HEMT with dual doped regions was the same as that of the conventional lateral surface superjunction device,both being 1/30 of that of the conventional polarized superjunction device.Furthermore,the lateral surface superjunction GaN HEMT with dual doped regions effectively weakened the high electric field peak at the end of the P-stripe of the conventional lateral surface superjunction device without compromising the forward performance,and the device’s breakdown voltage increased from 671 V to 1710 V.In addition,the parasitic capacitance of the lateral surface super-junction device was only 1/30 of that of the conventional polarized superjunction device,and the gate control capability was superior.Furthermore,the physical parameters of the lateral surface superjunction GaN HEMT with dual doped regions are studied,and the influence of these parameters on the voltage-resistant performance and forward characteristics of the device are analyzed and summarized.