GaN-on-SiC is preferred for RF applications because of the following characteristics.:
A. High breakdown field: GaN’s wide bandgap, allows it to achieve a high breakdown field. This means that the GaN device can operate at significantly higher voltages than many other types of semiconductor devices. However, excessively high electric fields, can cause the electrons in the device to generate high kinetic energies and result in voltage breakdown. If uncontrolled, it can cause problems for the device, not the least being degradation in performance.
B. High saturation velocity: GaN devices can run at a much higher current density. The reason is that electrons in GaN have a higher saturation velocity. GAN devices also have a higher capability for charge which leads to higher currents, a preferred characteristic in many types of RF applications since the RF power output is equal to the product of the voltage and the current. A higher voltage and current, generate higher RF power in a reasonable GAN transistor size, i.e GaN devices can be operated at higher power densities. A great feature that can be put to good use in RF power amplifiers among other applications!
C. Excellent thermal characteristics: GaN-on-SiC devices have excellent thermal properties. This is a consequence of the high thermal conductivity of SiC. As a result, GaN-on-SiC devices run cooler. A very good characteristic for any semiconductor device. A collateral result is, that the device is more reliable.
D.Piezoelectricity: GAN devices are also piezoelectric. This piezoelectricity leads to the generation of part of the charge in the device channel.
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