An Efficient GADI Method with Unstructured Grids for Transient Thermal Analysis of AlGaN/GaN HEMTs

In this paper, an efficient generalized alternating direction implicit (GADI) method with unstructured grids is proposed for transient thermal simulation of AlGaN/GaN high electron mobility transistors (HEMTs). To deal with the multiple feature sizes within GaN devices, locally refined grids are employed in the critical regions, ensuring the accuracy of results while reducing computational resources significantly. Based on the unstructured grids, the GADI method is developed by introducing two additional directions in the time-stepping process. By this means, the confinement of the traditional alternating direction implicit (ADI) method induced by the structured grid is successfully released. The proposed GADI method has advantages of linear complexity and unconditional stability. The accuracy and efficiency of this algorithm are verified by several numerical examples.