AlGaN/GaN HEMTs Thermal Resistance Reliability of HEMTs In this letter, thermal analysis results of AlGaN/GaN HEMTs grown on SiC, Si and Sapphire substrates were presented. Simulation results are in good agreement with experimental data from the literature. Effect of different device parameters such as substrate thickness, gate length, gate width, dissipated power and pulse width were investigated to determine in which range of these parameters GaN-devices provide the best thermal performance. Resulting thermal resistance values have been extracted for different substrates. In addition, transient thermal performance was studied for sub micrometer pulse width, and substrate material performances are compared. Figure A. Temperature distributions on cross section of AlGaN/GaN devices grown on SiC, Si and Sapphire substrates for 50 µm and 300 µm substrate thicknessesPurpose: This study facilitates the improvement of AlGaN/GaN HEMTs design to reduce thermal resistance, and also improves the reliability and life-time of these devices.
Theory and Methods:Fourier's law of conduction formula can be used to calculate thermal resistances and the 3-D finite element model is constructed to understand the thermal behavior of single-finger AlGaN/GaN HEMTs grown on SiC, Si and Sapphire substrates, using the commercial software package ANSYS-Icepak.
Results:According to numerical simulation results, device on Sapphire substrate has the highest thermal resistance, followed by device on Si, and then device on SiC substrate, due to the increasing thermal conductivity in this order.
Conclusion:According to present simulation results, GaN device grown on SiC has the best thermal performance. Finally, these results facilitate optimization of device layout that results in an effective thermal management and reliability improvement in high power technologies.