Comparison of electrical properties in GaN grown on Si(1 1 1) and c-sapphire substrate by MOVPE

The net doping characteristics of Si-doped n-GaN grown on Si(1 1 1) substrate and on c-sapphire substrate by MOVPE were investigated. In case the carrier concentration is less than 1×1017 cm−3, the n-GaN on Si has a strong compensation behavior. But it seems that it does not depend on carbon concentration as p-type dopant, but on other acceptors associated with crystal defects. AlGaN/GaN HEMTs were fabricated on both substrates. DC performance of the devices fabricated on Si substrate is in no way inferior to that of devices grown on sapphire substrate.