| Al Ga N/Ga N HEMTs have many advantages over conwentional devices. High density of 2DEG, high electron mobility and high breakdown voltage make Al Ga N/Ga N HEMTs to be a research focuse in the field of power electronic components. However, the breakdown voltage of present Al Ga N/Ga N HEMTs is still much lower than the theoretical value.In the aid of improving the breakdown voltage of Al Ga N/Ga N HEMTs, this thesis established a 2D Al Ga N/Ga N HEMT model by using the Sentaurus TCAD. With theory analysis and simulation, impact of acceptor traps on Al Ga N/Ga N HEMTs' leakage current and breakdown voltage was studied systematically, including the trap density and trap energy level. Simulation results showed that deep level and high density acceptor traps in Ga N buffer layer can effectively restrain the leakage current. Meanwhile, to improve the electrical field uniformity in Al Ga N/Ga N HEMTs, the modulation of the field plate on the channel electric field is investigated, the structures of gate connected field plate with short gate-drain distance, hybrid gate and interval drain field plates with short gate-drain distance are optimized by simulation. With the 3?m gate-drain distance, the breakdown voltage can reach 400 V with single gate connected field plate and that can be raised to 650 V with hybrid gate and interval drain field plates structure. Finally, impact of acceptor traps and field plates on Al Ga N/Ga N HEMTs' current and resistance was studied. Simulation results showed that, acceptor traps doping can restrain Al Ga N/Ga N HEMTs' current and the resistance slightly. Field plates have negligible negative impact on Al Ga N/Ga N HEMTs' current and resistance.The physical models and results of simulation optimization can be used to subsequent modeling of device characteristics and served as refercence for design and fabrication of Al Ga N/Ga N HEMTs. And can provie a theoretical basis and foundation to the future wore. |
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