Study On The SPICE Model Of The Enhancement-Mode P-GaN HEMT Device

Gallium nitride(GaN)material is one of the new power semiconductor materials with wide band gap,high critical breakdown electric field,high electron mobility,high charge density and many other advantages.GaN-based power semiconductor devices with superior performances have attracted wide attention.With the increasing demand for E-mode devices in the power electronics industry,the p-GaN HEMT device has begun to be applied in recent years.As the bridge between the device and the circuit design,a precise SPICE model of the p-GaN HEMT device is critical to the design of high performance power integrated circuits.However,the SPICE model developed for the p-GaN HEMT device is not yet mature,especially the accuracy needs to be improved.Therefore,the research on the p-GaN HEMT device model is of great significance.In this paper,a complete p-GaN HEMT SPICE model based on the surface-potential ASMHEMT core equation is developed,including the static electrical characteristic model and the dynamic electrical characteristic model.In the static electrical characteristic model,due to the dynamic broadening effect of the depletion region of the Schottky metal/p-GaN junction,the analytic formula for the voltage of the p-GaN layer is successfully deduced by using the principle of charge balance,and by implementing the analytical formula in the ASM-HEMT,the drain current of the pGaN HEMT is obtained.Meanwhile,according to the path and mechanism of the gate current in the p-GaN HEMT device,the equivalent circuit of two diodes in series is established,and the analytical formula for the gate current is deduced.In the dynamic electrical characteristic model,the change of the gate capacitance is described from the physical level,so the equivalent circuit of the Schottky junction capacitance and the pn junction capacitance in series is established,and then the analytical formula for the gate capacitance is established.In addition,some physical effects such as self-heating effect,series resistance effect,and carrier storage effect are also considered in the process of modeling.Finally,the SPICE model of the E-mode p-GaN HEMT device is realized by Verilog-A language,and the model at room temperature is validated by measured data.As the results,the mean square error(RMS)of the the static and the dynamic electrical characteristic model of the E-mode p-GaN HEMT device are within 5% and 10%,respectively.The compared results demonstrate that the model gives accurate descriptions for the electrical characteristics of the p-GaN HEMT device.The accuracy and convergence of the model meet the expected target.The E-mode p-GaN HEMT device SPICE model proposed in this paper has important guiding significance for the simulation design of power integrated circuits and systems.