Physics-Based 2-D Analytical Model for Field-Plate Engineering of AlGaN/GaN Power HFET

A physics-based 2-D analytical model is developed for AlGaN/GaN heterojunction field-effect transistor (HFET) to optimize the field-plate (FP) design for electric-field (E-field) engineering. The model reveals the impact of critical device parameters such as FP length, passivation dielectric, and dielectric thickness on the electric potential and E-field distribution in AlGaN/GaN HFET. With this model, a minimum FP length as well as the optimal dielectric thickness for different passivation dielectrics can be obtained to achieve a uniform E-field distribution and simultaneously at the minimized cost of parasitic capacitance. By taking the edge effect of both the gate and FP into account, the calculated results exhibit good agreement with numerical simulation. The developed model is of the great potential of high-voltage AlGaN/GaN HFET design for power switching applications.