Analytical Modeling on Investigating the Electric Field Shift Behavior of GaN Vertical FinFETs

GaN vertical FinFETs have emerged as an increasingly prevalent semiconductor technology for RF and power applications. To fully exploit GaN power transistors, accurate and reliable physics-driven models have been required. An analytical model based on surface potential for vertical GaN FinFETs featuring a submicron fin channel on a GaN substrate is presented, considering the electrostatic influence of a field plate gate. A two-dimensional Poisson equation is analyzed using the parabolic estimation to characterize the electrostatic potential along the fin channel. Thereby, the surface potential model provides insight into the determination of threshold voltage, electrostatic control, and drain current. In addition, an ON-resistance model has also been derived to analyze the device performance. Then, the derived models are compared with the simulated results of a field plate-added stepped gate device obtained from TCAD. The simulated device based on this analytical model provides an ON current of 4 kA/cm² associated with its specific ON resistance of 0.012 mΩ·cm². This analytical approach provides a reliable platform for optimizing the electrostatic design of GaN vertical FinFET devices.