As of MATLAB R2023a, we do not have Simscape blocks for GaN or SiC FETs. However, there are several ways to implement or model a GaN or SiC FET depending on the end goal.
If you are using a GaN High-electron-mobility transistor (HEMT) as a switching device, then you can use the standard "N-Channel MOSFET" block. Switching devices only need to fit in the linear and off-states, so it should be enough to specify the "Drain-source on resistance," R\_DS(on) and the "Gate-source threshold voltage," Vth. In order to get the capacitances correct, the easiest approach is to go to the "Junction Capacitance" tab and choose "Specify tabulated input, reverse transfer and output capacitance" as the "Parameterization." This data is usually provided on datasheets.
If you need to fit more towards the knee of the DC I-V characteristic (for example, designing a power amplifier), the easiest approach is to use the "N-Channel IGBT" block, and choose "Lookup table (2-D temperature independent)" from the "I-V characteristics defined by" menu. Here, you can take the I-V curves from the datasheet and input them as tabulated data to the block. You may also select the same tabulated option on the "Junction Capacitance tab." Using tabulated I-V curves is an easy way to get quasi-saturation in the I-V.
Moreover, if you have the SPICE subcircuit of the GaN or SiC device, you can use the "ee.spice.semiconductorSubcircuit2lookup" function to generate lookup table data. The documentation for this function is below:
One such example to model SiC MOSFET is attached:
Alternatively, you can also use "subcircuit2ssc" to convert SPICE subcircuit into equivalent Simscape component. The function documentation is:
