Study On Breakdown Characteristics Of High Electron Mobility Transistors Based On Gallium Nitride

GaN materials have many excellent properties,such as wide band gap,high critical electric field and high electron mobility.As a representative of GaN-based electronic devices,AlGaN/GaN HEMT has broad application prospects in the field of microwave high-power.The breakdown voltage is an important parameter for GaN devices to improve power and conversion efficiency.By introducing the field-plate structure,the withstand voltage characteristics of the devices can be effectively improved.In this paper,the breakdown voltage of three field-plate structures of gate,source and drain is simulated and compared,the field-plate structure and related parameters are optimized,and the schemes to improve the breakdown voltage under different structures are given respectively.Silvaco simulation software is used to simulate the classic T-type field-plate GaN HEMT device,and the trend of the electric field peak value with the length of the fieldplate is analyzed.The structure model of the ?-type gate field-plate GaN HEMT device was established,the relevant parameters of the gate field-plate structure device were optimized.The breakdown voltage values under different parameters were simulated and calculated.By optimizing the field-plate length,thickness and passivation layer thickness and other parameters,the breakdown voltage of the device is increased from 366 V in the fieldless plate structure to 1046.8V.After the source/drain length and thickness are optimized,the breakdown voltage reaches 1062 V.By adding the field-plate structure and optimizing its parameters,the breakdown voltage of the device is increased by 1.9 times.In order to further optimize the structure,the ?-type source field-plate GaN HEMT device is studied in this paper.The relevant parameters of the gate field-plate structure device were optimized,and the breakdown voltage values under different parameters were simulated and calculated.By optimizing the gate-to-drain spacing and the thickness of the passivation layer,the breakdown voltage of the device is increased from 610 V in the fieldless plate structure to 1241.8V.After the concentration and thickness of the barrier layer,and drain length are optimized,the breakdown voltage reaches 1389 V.Compared with the gate field-plate structure,the breakdown voltage of the source field-plate structure is increased by 30.8%.Finally,the drain field-plate structure is introduced to simulate the effect of double field-plate structure on the breakdown characteristics of the device.