High Speed Transient Thermal Simulation of GaN HEMT Devices

As the power density of GaN HEMT devices increases, its internal operating temperature increases sharply, which would affect the electrical characteristics of devices and greatly limit the service life. The operating temperature has become an important technical index to evaluate the thermal design level of GaN HEMT devices. In this work, a high-speed transient thermal simulation method for GaN HEMT devices is proposed to enable the finite element thermal analysis with high efficiency and accuracy. Based on the law of energy conservation, the functional relationship between the trough temperature and time of the transient operation is built. Then the transient trough temperature is calculated using the limit solution algorithm when the device reaches a stable state, and the initial temperature of the model is set by loading a constant temperature heat source. The finite element analysis software FloTHERM is used to calculate a small number of pulse stress cycles and then quickly obtain the transient temperature field of the dynamic equilibrium state of GaN HEMT device. It is found that the fitting degree is very high compared with the traditional simulation method. This method effectively obtains the transient temperature distribution of GaN HEMT device at any time after dynamic equilibrium, but also avoids the calculation process over ten million cycles before reaching dynamic temperature equilibrium and greatly reduces the simulation time and computational cost.