Thermal evaluation of GaN-based HEMTs with various layer sizes and structural parameters using finite-element thermal simulation

By using scanning electron microscopy (SEM) and infrared data, we established and verified a two-dimensional finite-element model conforming to the size of the practical device to study high-electron-mobility transistors (HEMTs). Because the resolution of the infrared measurement was 7 μm, we verified the correctness of the model by comparing the 7-μm average peak temperature with the measured infrared data at various platform temperatures. The simulated average peak temperature agrees well with the infrared data. To further investigate the thermal performance of GaN-based HEMTs with various layer sizes and structural parameters, we simulated devices with various values of gate length, gate spacing, GaN layer thickness, substrate breadth, and substrate thickness. The conclusions presented result from some factors that must be taken into account to manage thermal issues in devices.