Comparison of SiC and GaN substrates used for epitaxy of HEMT structures

The work shows new results showing advantages and disadvantages of using GaN and off-oriented SiC for high-electron-mobility-transistors fabrication. We will show a difference of defect density what influences the leakage current of the Schottky diodes, as well as thermal conductivity what is of importance in high-power devices. Possible influence on the life-time and noise level will be also discussed. Special attention will be paid to the substrate off-orientation. In the case of SiC substrates, 2-deg off may lead to cheaper technology of high-frequency devices and integrating GaN-based and SiC-based devices. In the case of GaN substrates, the off-orientation must be optimized as it influences the point-defect concentration, cracking, and layer morphology.