Study Of The Floating Field Plate In AlGaN/GaN HEMTs

AlGaN/GaN HEMTs are regarded as the most attractive one for high-powermicrowave devices because of the high2DEG concentration, the high saturatedvelocity,besides,they can work at high temperature thanks to GaN’s large bandgap.However, there are still some problems to solve: how to improve the maximum outputpower and to get higher output power adder efficiency. It is widely accepted that we canincrease the output power by increasing the breakdown voltage of the devices. Thepaper here discusses the Field Plate structure which can improve the breakdown voltageof devices. The major achievements are as follows:Studied the laws of optimizing the parameters of the traditional FP structure;Present a new structure called floating field plate, then contrast the traditionalHEMTs, the FP-HEMTs and the FFP-HEMTs by theoretical analysis. Besides, the rulesof the FFP-HEMTs’ optimization by simulation are also studied. On the basis ofsimulation, the FFP-HEMTs are fabricated and tested. It increased the breakdownvoltage by253V, from60V to313V.The floating field plate is used in the double field plate(the gate FP and the drainFP) structure to increase the breakdown voltage more. The FFP-DH-HEMTs structure issimulated and analyzed theoretically. One of the optimal result is given.Above all, the floating field plate structure is studied successfully from the pointsof theory, simulation and experiments. Also,the FFP-DH-HEMTs devices are analyzedby theory and simulation.