A Universal Scalable Thermal Resistance Model for Compact Large-Signal Model of AlGaN/GaN HEMTs

Abstract

This paper presents a universal scalable thermal resistance model for AlGaN/GaN high electron-mobility transistors (HEMTs), which can be easily implemented into compact large-signal models and is very suitable for rapid device modeling. It contains all the key HEMT device geometric parameters such as gate length, gate width, gate pitch, and different layer thicknesses. The temperature-dependent conductivities of different materials are taken into consideration. The via-holes effects on the thermal resistance of a device are also included, which is considered for the first time in a compact largesignal model. Two uniform parameters are used to simplify the complicated analytical closed-form expression of thermal resistance, which is difficult to be implemented into the compact model. Another two uniform parameters are used to simplify the complicated transcendental function of the temperature rise with respect to the temperature-dependent thermal conductivity. Thus a simple, accurate, and scalable thermal resistance model can be obtained. The results are verified by comparing with experimental and finite-element numerical simulations. The dc I-V characteristics and large-signal performances of HEMTs devices with different gate lengths 0.15, 0.25, and 0.4 μm are used for further verifications. The proposed thermal resistance model can also be used to optimize the structural geometry of a device to obtain minimum thermal resistance.