A Study On The GaN HEMT With A Novel Polarization Superjunction

Compared with traditional semiconductor materials,Ga N,which is one of the third generation semiconductor materials,has high breakdown electric field and high temperature tolerance.Compared with Si C,Ga N based materials can be used to form the heterojunctions with high-concentration two-dimensional electron gas due to the significant polarization effects.This makes Ga N based materials stand out in wide band gap semiconductors.Therefore,Ga N HEMTs can work at high temperature and high frequency and have high breakdown voltage.In order to improve the breakdown voltage of GaN HEMT in a further step,researchers have proposed many voltage sustaining structures,among which the polarization superjunction has great advantage.However,the conventional polarization superjunction carrys a large parasitic capacitance,which limits the devices frequency character.In view of this,a novel polarization superjunction with Al Ga N/Ga N/Al Ga N sandwich structure is studied in this thesis,and the HEMT with this superjunction is investigated using TCAD.The calculation results show that the breakdown voltage and on-resistance of the device are 1823 V and 16m?·mm respectively.The simulation of Ga N HEMT with conventional polarization superjunction is also done for comparison.The results show that the parasitic capacitance of the novel polarization superjunction is only 1/88 of that of the conventional polarization superjunction.This makes the former device has better frequency character.In this thesis,the physical parameters of the novel polarization superjunction are also studied,and their effects on device's performance are evaluated.In addition,the charge imbalance in this superjunction is also investigated.