A Physics-Based Hybrid Model for GaN HEMT Devices Utilizing Substrate Bias Modulation

In order to meet the urgent need of multi-dimensional controllability and predictability of GaN devices in emerging monolithic and integrated circuits, a physical analytic hybrid model of GaN HEMT devices based on substrate bias regulation is constructed in this paper. The model deeply explores the changes of electrical characteristics of devices under different substrate bias conditions, takes into account the capacitive voltage divider model formed under substrate bias, effective mobility degradation model and substrate bias dependent threshold voltage model, and combines with the physical high electron mobility Advanced circuit model (ASM-HEMT) based on surface potential. The analytical expression of leakage current is derived accurately to characterize the I-V characteristics of GaN HEMTs. In addition, the voltage-dependent capacitance is characterized by a current-controlled current source, and the C-V characteristics of GaN HEMTs are modeled more accurately on the basis of the classical Angelov model. This model is constructed based on Verilog-A language and relies on Keysight ICCAP platform to complete physical parameter extraction. The fitting error between the model data and the measured data is less than 3%. This fully shows that the model proposed in this paper can effectively describe the effect of substrate bias regulation on the electrical characteristics of devices.