The analysis model of AlGaN/GaN HEMTs with electric field modulation effect

This paper reviews the AlGaN/GaN HEMT devices with electric field modulation effects and proposes a uniform two-dimensional model of this type of devices. The surface electric field can be optimized to improve the breakdown voltage by the electric field modulation based on changing the charge distribution inside the device. And four AlGaN/GaN HEMTs with electric field modulation effects have been discussed: AlGaN/GaN HEMT with the etched AlGaN layer, AlGaN/GaN HEMT with partial GaN cap layer, the RESURF AlGaN/GaN HEMT and AlGaN/GaN HEMT with partial silicon doping. On the basis of the above analyses, a uniform analytical model of the surface electric field and potential distribution are obtained by reasonable boundary conditions and the two-dimensional Poisson equation. The simulation results agree well with the analytical results, and it verify the correctness of theoretical analysis and the validity of the model. In addition, AlGaN/GaN HEMT with etched AlGaN layer and AlGaN/GaN HEMT with partial GaN cap layer were fabricated and tested. The experimental results indicated that the novel AlGaN/GaN HEMT with electric field modulation effects is superior to conventional HEMT, which further proves the accuracy of the theoretical model. This uniform model can provide valuable reference for the modelling of other devices.